Two new luminescent Cd(II)-metal–organic frameworks (MOFs), {[Cd(L)(BPDC)]·2H2O}n (1) and {[Cd(L)(SDBA)(H2O)]·0.5H2O}n (2) [L = 4,4′-(2,5-bis(methylthio)-1,4-phenylene)dipyridine, H2BPDC = 4,4′-biphenyldicarboxylic acid, H2SDBA = 4,4′-sulfonyldibenzoic acid], have been solvothermally synthesized using Cd2+ ion and L ligand in the presence of auxiliary ligands and characterized by infrared spectroscopy, elemental analysis, powder X-ray diffraction, and thermogravimetry measurement. Topological analyses reveal that MOF 1 is a 6-connected 3-fold interpenetrating pcu network, and MOF 2 is a new 4-connected 2-fold interpenetrating network. Fluorescence titration, cyclic and anti-interference experiments demonstrate that MOFs 1 and 2 both are excellent probes for Fe3+, CrO42–, and Cr2O72–. The mechanisms of quenching are also deeply studied.

•Two MOFs have been obtained by the self-assembly of mixed-ligands and metal ions.•They possess fluorescent turn-on or turn-off sensing behavior for metal ions.•They are highly selective probes for detection of PA in DMF solution.Two new coordination polymers, {[Zn4(DPBT)2(BDC)4]·(H2O)·2(DPBT)}n (1), {[Cd2(DPBT)2(BDC)2]·(DMA)}n (2), have been obtained from the self-assembly of the heterocycle ligand DPBT with different d10 metal ions, in the presence of BDC2− coligand. Interestingly, the emission spectra exhibit that both compounds possess fluorescent turn-on or turn-off sensing behavior for different metal ions. Compared with the other metal ions, Fe3+ shows significant quenching effect and Al3+, Cr3+show enhancement effect on the fluorescence intensity for 1. The fluorescence intensity of 2 progressively enhance with the increase of concentrations of Al3+, Cr3+ and Pb2+ ions. In addition, the photofluorescent titration upon the addition of nitrate salts to 1's and 2's emulsions were also conducted. They are developed as highly selective and sensitive probes for detection of PA in DMF solution based on fluorescence quenching with a detection limit of 0.01 μM and 0.1 μM, respectively.Both compounds are, so far, the most efficient selective and sensitive probes for detection of PA (picric acid) in DMF solution with detection limit of 0.01 and 0.1 μM, respectively, and the promising fluorescent sensory materials to detect metal ions.

Two new networks, namely, {[Cd(bpba)(H2bptc)1/2·H2O]}n (1), {[Co(bpba)(bdc)1/2]}n (2), where Hbpba = 3,5-bis(pyridin-4-ylmethoxy)benzoic acid, H4bptc = 3,3′,5,5′-biphenyltetracarboxylate, H2bdc = 1,4-benzenedicarboxylate, have been synthesized hydrothermally and characterized. Compound 1 is a three-dimensional net with a rare jea topology. The flexible pyridyl arms may afford a dimension extension in the crystal structure. While for compound 2 the flexible pyridyl arms are not involved in coordination, the Co(II) paddle-wheel secondary building units are bridged by the mixed ligands, bpba– and bdc2–, to furnish a two-dimensional layer. In addition, their heterogeneous catalytic oxidation activities toward methyl orange, methyl blue, neutral red, methylene blue, and safranine T (ST) in the presence of H2O2 are investigated in aqueous solution. The results suggested that the photocatalytic efficiency of ST is found to be 100% for MOF-2.

•Durian-shaped magnetic porous UiO-66 composites (MSU(Zr)) were prepared.•MSU(Zr) show highly equilibrium adsorption capacity for nitrophenol.•The recycling adsorption-desorption performance could be adjust with pH.Highly effective decontamination of nitrophenols from aqueous solution is a challenge for public health and ecosystem protection. Here we report the assembly of UiO-66 onto Fe3O4 particles by solvothermal method, formed durian-shaped magnetic porous composites (MSU(Zr)) with multi-core-shell structure. The weight ratio of UiO-66 shells and the Fe3O4 multi-core is about 6:4. MSU(Zr) performed well on 2-nitroresorcinol (NRC) adsorption, which could be attributed to the highly porosity and the nature of Lewis base of Zr6O4(OH)4 clusters. The equilibrium adsorption capacity for NRC is more than 200 mg g−1, which means that each Zr6O4 centre can uptake more than three NRC molecules (MSU(Zr)·3NRC). Kinetic parameters follow pseudo-second-order kinetics and Langmuir isotherm. pH value plays a significant role on NRC adsorption, which is more favor at acidic condition. It’s remarkable that the reversible adsorption-desorption performance could be adjust with pH. The reusability of MSU(Zr) shows a good recyclability that the adsorption capacity is still more than 180 mg g−1 after five regeneration cycles.A new durian-shaped magnetic porous Fe3O4@SiO2@UiO-66 composites (MSU(Zr)) was prepared and applied in removal of nitroresorcinol (NRC) from aqueous solution. MSU(Zr) performs well on NRC adsorption, the equilibrium adsorption capacity is more than 200 mg g−1 (MSU(Zr)·3NRC). pH value plays a significant role on NRC adsorption, which is more favor at acidic condition. It's remarkable that the recycling adsorption-desorption performance could be adjust with pH. The combination of magnetic separation with MOFs is attractive way for efficient and renewable removal of nitrophenol from waste water.Download high-res image (94KB)Download full-size image

•One anionic complex [Co(H2O)6]2 +. [Co3(bptc)2(H2O)10]2 −. 3H2O has been synthesized.•The bptc4 − connect the Co2 + to form a 2D layer with 1D pseudo channels encapsulation of [Co(H2O)6]2 + guest.•The dye adsorption results suggested that the anionic complex 1 show rapid and selective adsorption of cationic dyes.One new anionic Coordination Polymer, namely [Co(H2O)6]2 +·[Co3(bptc)2(H2O)10]2 −·3H2O (1), where H4bptc = 3,3′,5,5′-biphenyltetracarboxylate, has been synthesized hydrothermally and characterized. In compound 1, bptc4 − as tridentate ligands connect the Co2 + cations to form a 2D layer with 1D pseudo channels encapsulation of [Co(H2O)6]2 + guest. In addition, their adsorption activities for organic dyes were investigated in aqueous solution. The results suggested that the anionic complex 1 show rapid and selective adsorption of cationic dyes for Neutral red, Methylene blue.One new anionic complex [Co(H2O)6]2 +·[Co3(bptc)2(H2O)10]2 −. 3H2O (1), has been synthesized. The bptc4 − as tridentate ligands connect the Co2 + cations to form a 2D layer with 1D pseudo channels encapsulation of [Co(H2O)6]2 + guest. The dye adsorption results suggested that the anionic complex 1 show rapid and selective adsorption of cationic dyes for Neutral red, Methylene blue.Download high-res image (123KB)Download full-size image

•Both compounds show strong luminescence at room temperature.•Luminescence of both compounds could be quenched by a series of nitroaromatic explosives.•Both compounds exhibit very highly sensitive and selective detection of picric acid compared to other nitroaromatic explosives.Two new luminescent Zn(II) metal–organic frameworks (MOFs) have been solvothermally synthesized from a p-conjugated carbazole-containing pyridine ligand in the presence of auxiliary ligands. Both MOFs were characterized by single crystal X-ray diffraction, infrared spectroscopy, elemental analysis and X-ray powder diffraction. Both MOFs show strong luminescence and their luminescence could be quenched by a series of nitroaromatic explosives. Importantly, they exhibit very highly sensitive and selective detection of picric acid compared to other nitroaromatic explosives.SynopsisTwo new luminescent Zn(II) metal–organic frameworks (MOFs) have been solvothermally synthesized from a p-conjugated carbazole-containing pyridine ligand in the presence of auxiliary ligands. Both MOFs show strong luminescence and their luminescence could be quenched by a series of nitroaromatic explosives. Importantly, they exhibit very highly sensitive and selective detection of picric acid compared to other nitroaromatic explosives.Percentage of photoluminescence quenching of 1 and 2 depends upon addition of different explosive analytes.Download high-res image (51KB)Download full-size image

Four Cd(II)-based compounds (1–4) were synthesized from solvothermal reactions involving the in situ aldimine condensation of an o-diamino-functionalized precursor 3,6-di(4H-imidazol-4-yl)benzene-1,2-diamine (L), Cd(NO3)2·4H2O and aldehyde. Two modes of cycloaddition ([4 + 1] cycloaddition and [4 + 2] cycloaddition) occurred during condensation, causing the in situ generation of two benzimidazole derivative ligands (L1 and L3) and a quinoxaline derivative ligand (L2). Furthermore, the chemical selectivity of the condensation was studied, where the condensation of o-diamino and the aldehyde is more stable and easy to operate. This strategy enriches the synthesis method of MOFs. Additionally, compound 2 containing uncoordinated quinoxaline N atoms showed excellent luminescent sensitivity for Fe3+ detection.

Metal–organic frameworks (MOFs), self-assembled from metal ions or metal clusters with organic ligands, are well known for their intriguing structure, permanent porosity, and tunable properties and have shown great prospect for various applications. In the present review, we mainly highlight recent significant examples of metal clusters in our team and provide a comprehensive review on the structure of metal cluster-based MOFs and their applications including for sensing metal ions, small molecules and gases, nitroaromatics and explosives, as well as many other applications. We classified two different coordination polymers: (i) homometallic coordination polymers (examples of coordination polymers with single and mixed types of secondary building units) and (ii) heterometallic coordination polymers (examples of coordination polymers based on metal–oxygen clusters and W–Cu–S clusters).

Two lanthanide metal–organic frameworks (Ln-MOFs) with similar structures have been synthesized through objective synthesis. The two compounds are both 2-fold interpenetrating 3D frameworks. Topological analyses reveal that complexes 1 and 2 are 6-connected pcu net. In addition, both structures were embedded in uncoordinated nitrogen atoms. As the uncoordinated pyridine groups can be used as functional groups, we tested their sensing ability toward metal ions and small organic molecules. To our delight, fluorescence measurements show the two complexes can selectively and sensitively detect for Fe3+ ion and nitromethane, which suggests that the two Ln-MOFs are promising bifunctional luminescence sensor materials with sensing metal ions and small organic molecules.Keywords: fluorescence detection; Ln-MOFs; nitromethane; sensor materials; uncoordinated site;

By employing a rational design approach, we synthesized three luminescent metal–organic frameworks (MOFs) 1–3 affording different coordination modes of V-shaped thienylpyridyl ligand. Their application in detecting metal ions was explored, and the mechanism was inferred. And the result exhibits that MOF 3 is a dual-responsive luminescent probe for Fe3+ and Al3+ ions.

•Complexes feature different 3D supramolecular frameworks with sql topologies.•Complex 1 exhibits photoluminescence emission at room temperature.•Complex 2 reveals antiferromagnetic interactions between binuclear Cu(II) ions.Two new Zn(II)/Cu(II) coordination polymers, [Zn(OPBT)(GA)]n (1) and {[Cu2TTPA(GA)2]·1.5H2O}n (2), have been successfully synthesized from flexible glutaric acid (H2GA) with different bi- and tritopic 1,2,4-triazole derivatives (OPBT = 1.1′-(oxybis(1,4-phenylene))bis(1H-1,2,4-triazole), TTPA = tris(4-(1H-1,2,4-triazol-1-yl)phenyl)amine) and Zn(II)/Cu(II) nitrate salts. Their structures have been characterized by infrared spectra, elemental analyses, single crystal and powder X-ray diffraction analyses and thermogravimetric analyses. Both complexes 1 and 2 feature different 2D layers with sql topologies, which can be further arranged ABAB-type, leading to different 3D supramolecular frameworks by C-H···O hydrogen bonding or O-H···O/N hydrogen bonding/π···π stacking interactions. Moreover, the photoluminescence spectra of complex 1 are examined and variable-temperature magnetic susceptibility measurements of complex 2 reveal antiferromagnetic interactions between binuclear Cu(II) ions of paddle-wheel second building units (SBUs).Two new Zn(II)/Cu(II) complexes based on bi- and tritopic 1,2,4-triazole derivatives feature different 2D layers with sql topologies. Moreover, complex 1 exhibits photoluminescence emission and complex 2 reveals antiferromagnetic interactions between binuclear Cu(II) ions.Download high-res image (278KB)Download full-size image

•Complex 1 displays a rare doubly-interpenetrating (3,5)-connected hms topology.•Compound 1 is potential material for the storage and separation of CO2 and CH4.•Compound 1 exhibits strong fluorescent emission at room temperature.A new coordination polymer was solvothermally prepared based on a semi-rigid multidentate carboxylic acid ligand and benzimidazole (bimid) ligand (H3L = 4,4′,4″-(((2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene))tris(oxy))tribenzoic acid): [Cd2(L) (bimid) (DMF)2]·(DMF)3·(H2O)2 (1). The complex 1 was characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry measurement, elemental analysis and X-ray powder diffraction. Structure analysis reveals that complex 1 displays a rare doubly-interpenetrating (3, 5)-connected hms network with a point symbol {63}{69.8}. Moreover, the fluorescence and gas adsorption properties of the compound 1 were also explored.A new Cd(II) coordination polymer with a rare doubly-interpenetrating (3,5)-connected hms topology exhibits strong fluorescent emission upon excitation at room temperature. The gas adsorption result indicated that compound 1 is potential material for the storage and separation of CO2 and CH4.Download high-res image (91KB)Download full-size image

A pair of new enantiomeric Zn(II) complexes with 5-fold interpenetrating diamondoid frameworks have been synthesized using two achiral tritopic and V-shaped ligands through spontaneous resolution, which crystallize in orthorhombic crystal systems with chiral P212121 space groups, showing a strong second harmonic generation response. In the presence of enantiopure propane-1,2-diol as a chiral inducing agent, they are driven to controllable homochiral crystallization of the desired enantiomorph, confirmed by single crystal X-ray diffraction and circular dichroism spectroscopy.

Enantiomorphism and enantioselectivity are critical in biology and many other applications. Herein, we report two 3D chiral MOFs {[Zn6(MIDPPA)3(1,2,4-btc)3(NO2)3(H2O)3](H2O)7}n (1L and 1R) based on achiral ligands with high enantiomeric excess and a novel topological type. The internal mechanism of spontaneous chiral symmetry breaking, during the crystallization of chiral MOFs based on achiral ligands, is elucidated for the first time from both structural and theoretical aspects. Hydrogen bonds are found to play a key role in the spontaneous symmetry breaking of chiral MOFs. Also, DFT calculations support our findings from the aspects of total energies and HOMO–LUMO energy gaps. Both 1L and 1R, exhibiting green fluorescence, present a non-centrosymmetric polar packing arrangement, resulting in good ferroelectric behaviors and second-order nonlinear optical effects.

•Three novel dyes are prepared by tuning the steric hindrance of auxiliary donors.•Adsorption properties of dyes are studied with X-ray photoelectron spectroscopy.•Dye with largest auxiliary donor has the smallest tilt angle on TiO2.Three new D-D-π-A sensitizers ZHG5, ZHG6 and ZHG7 have been prepared by gradually improving the steric hindrance of auxiliary donors and the power conversion efficiencies (PCE) are 5.64%, 5.32% and 2.74%. UV–Vis absorption indicates that the molar extinction coefficients decrease with the increased steric hindrance of auxiliary donors. X-ray photoelectron spectroscopy (XPS) indicates that the tilt angles of ZHG5 and ZHG6 anchored on the TiO2 film are similar and ZHG7 is almost standing rather vertical on the TiO2 film with the smallest tilt angle. The results of dye desorption and XPS experiments indicate that the dye loading amount of ZHG6 with larger steric hindrance is lower than that of ZHG5, ZHG7 with largest auxiliary donor has the maximum loading amount probably due to its smallest tilt angle. Larger auxiliary donor of ZHG6 leads to higher open circuit voltage (Voc = 734 mV) but lower shorter circuit current (Jsc = 12.63 mA cm−2) compared with that of ZHG5 (Voc = 730 mV, Jsc = 12.06 mA cm−2). However, dense packing of dye ZHG7 anchored on the TiO2 leads to more serious intermolecular π-π aggregation effects. Perhaps this effect and lowest molar extinction coefficient are the reason that DSSC based on ZHG7 have the lowest PCE. So above results indicate that auxiliary donor with overlarge steric hindrance will have smaller tilt angle of dye anchored on TiO2 and may lead to more dye loading amount but serious intermolecular π-π aggregation effects.Auxiliary donor with overlarge steric hindrance will have smaller tilt angle of dye anchored on TiO2 and will lead to more dye loading amount but serious intermolecular π-π aggregation effects.Download high-res image (232KB)Download full-size image

We prepared three new push–pull dyes JA3, JA4 and JA0 through structure optimization, and applied them in DSSCs. Judicious molecular structure optimization of dyes can significantly improve the performance of DSSCs. Spirobifluorene as a building block was introduced onto the phenothiazine donor groups. Compared to JA1, the steric effect of the spirobifluorene building block can effectively reduce charge recombination by preventing the I3− of the electrolyte penetrating into the TiO2 surface, thus the Voc of JA3 increased from 701 mV to 800 mV. In order to further improve the light-harvesting ability of the DSSC, we introduced a benzothiadiazole unit (BTD) and prepared D–A–π–A dye JA4. As expected, the Jsc of JA4 increased from 12.32 to 14.43 mA cm−2 compared to that of JA3, and the device reached the highest PCE of 7.0%. Moreover, since extending the π-conjugated system is known to decrease the Voc of DSSC, the porphyrin unit was removed and dye JA0 was synthesized. Notably, the DSSC based on JA0 reached a very high Voc of 840 mV and a high PCE of 6.69%: to our knowledge, this is the highest Voc for DSSCs based on phenothiazine dyes with I−/I3− electrolyte.

Three Co(II) metal–organic frameworks (MOFs) were synthesized employing a rational design approach. On the basis of the different structures of three complexes, we tested their absorption properties toward two anionic dyes. The absorption results indicate that not only uncoordinated functional groups in the structure play an important role in adsorbing capacity but also physical forces can affect absorbing ability. Water stability testing shows that three crystals display high stability in aqueous solutions with different pH values. To our delight, the framework integrity of three complexes can be well-retained even after absorbing dyes.

Two luminescent Cd(II) metal–organic frameworks (MOFs) were prepared from electron-rich π-conjugated fluorescent ligands. They are isostructural with sql nets. Their strong luminescences can be quenched by a series of nitroaromatic explosives. Notably, MOF 1 shows highly selective and sensitive detection of 4-nitrophenol (4-NP), while MOF 2 exhibits good responses toward picric acid (PA) compared with other nitroaromatic explosives. This different order of quenching efficiency is because there are H-bonding interactions between MOF 1 and 4-NP, while MOF 2 lacks these H-bonding interactions. MOF 1 displays highly selective and sensitive detection of 4-NP with the high quenching constant (6.74× 104 M–1) and low detection limit (34.48 ppb), which is better than those of known MOFs. MOF 1 and MOF 2 have highly sensitive and selective detection of 4-NP and PA in the practical application, respectively.

Five new isomorphic coordination polymers of the Co(II) ion, namely, {[Co2L(bpy)0.5(H2O)2]·2H2O}n (1), {[Co2L(pbyb)0.5(H2O)2]·3H2O}n (2), {[Co2L(dpe)0.5(H2O)2]·2H2O}n (3), {[Co2L(dpa)0.5(H2O)2]·2.5H2O}n (4), and {[Co2L(dip)0.5(H2O)2]·3.5H2O}n (5) (H4L = cis,cis,cis,cis-1,2,3,4-cyclopentaneteracarboxylic acid, bpy = 4,4′-bipyridine, pbyb = 1,4-di(pyridine-4-yl)benzene, dpe = 1,2-di(pyridine-4-yl)ethane, dpa = (E)-1,2-di(pyridin-4-yl)diazene, and dip = 1,4-di(1H-imidazol-1-yl)benzene), have been synthesized under hydrothermal conditions. The L4– ligand maintains its original conformation of SSRR in all of these compounds, but {Co5L}n clusters show mirror coordination symmetry in 1, 2, and 4 while the clusters in 3 and 5 do not. The addition of different N-ligands can tune the distance between {Co2L}n layers and change the pore structures of the frameworks. Magnetic susceptibility measurements indicate that 1–5 exhibit antiferromagnetic behavior.

Solvothermal syntheses in DMF (or DMA) and H2O afforded four novel metal–organic frameworks: {[Cd(DPBT) (BDC)]·2(H2O)}n (1), {[Zn2(DPBT)2(IPA)2]·2(DMA)}n (2), {[Co2(DPBT)2(BDC)2]·2(DMF)·5(H2O)}n (3), and {[Ni(DPBT)2(H2O)4]·(BDC)}n (4) (DPBT = 4,7-di(4-pyridyl)-2,1,3-benzothiadiazole, BDC = 1,4-benzene dicarboxylate, IPA = isophthalic acid, DMA = N,N-dimethylacetamide, and DMF = N,N-dimethylformamide). X-ray analyses show that 1 and 3 show similar structures with the same building blocks and possess 3-dimensional 6-connected pcu net. Compounds 1 and 3 are based on a 2-fold interpenetrating network with solvent molecules located in the framework, whereas 3 is different in the absence of DMF solvent molecules. Compared with compounds 1 and 3, 4 is constructed under the same conditions except with metal ions and possesses a completely different structure type. Luminescence properties of 1 and 2 without any activation well-dispersed in common solvents have also been investigated systematically; the luminescence properties show different intensities depending on the nature of the solvents, especially for nitrobenzene (NB), which exhibits a significant quenching effect. Compound 2 possesses a layered structure; the distance between two parallel layers is big enough to allow small molecules to more easily move into the crystal skeleton and interact with each other. Thus, the luminescence responses of 2 were investigated for various nitro compounds. When the concentration of PA is up to 0.1 mM, the emission of 2 is completely quenched. These results show that compound 2 has great potential to be developed as the favorable sensor for highly selective detection of PA. Furthermore, the magnetic properties of compound 3 were investigated.

Four different Co(II) coordination polymers have been built by two flexible ligands 4,4′-dicarboxydiphenyl sulfone (4,4′-sdb) and 1,4-bis((1H-imidazol-1-yl)methyl) benzene (BMB) in a one-pot solvothermal reaction. The structures of 1 and 2 are new, and 3 and 4 have been reported. The crystal structures of 1–3 were obtained, namely [Co(4,4′-sdb)(BMB)]n (1), {[Co2(4,4′-sdb)2(BMB)]·2H2O}n (2), and [Co3(4,4′-sdb)2(DMF)(H2O)3]n (3), but 4 was confirmed by PXRD. Both 1 and 2 are 2D layered structures with sql topology and their point symbol is {44·62}. These complexes have been characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction measurements. By changing the synthesis conditions, four different Co(II) coordination polymers can be obtained respectively.

Four new metal–organic frameworks have been synthesized under hydrothermal conditions by the self-assembly of a N-centered multidentate bifunctional ligand (H2L: 4,4′-((4-(pyridin-4-yl)phenyl)azanediyl)dibenzoic acid) with different N-containing heterocyclic coligands (BIMB = 4,4′-bis((imidazol-1-yl)methyl)biphenyl, BPY = 4,4′-bipyridine, BIP = 1,4-bis(imidazol-1-yl)phenyl) and transition metal salts (Co(NO3)2·6H2O, Zn(NO3)2·6H2O). They are [Co(L)(BIMB)0.5(H2O)]·2DMF (1), [Co(L)(BPY)0.5(H2O)2]·3DMF·2H2O (2), [Zn2(L)2]·4DMF·3H2O (3), and [Zn2(L)2(BIP)]·2DMF·2H2O (4). Compound 1 is an infrequent 3,4-connected self-penetration three-dimensional (3D) architecture. Compound 2 has been classified as a trinodal (3,4,4)-connected 3D sqc69 framework. Compound 3 displays a 2-fold interpenetrating 3D net based on the [Zn2(CO2)4] units which are connected by L2– ligands. For compound 4, the larger potential voids lead to a 4-fold interpenetration, which can be classified as type IIIa. In addition, their thermal stability, the adsorption isotherms, and optical properties have been studied in detail.

Using reticular chemistry allowed the design and construction of four novel Zn(II)/Cd(II) coordination polymers, {[Zn(BTPA)(TPA)]·H2O}n (1), {[Zn(TTPA)(TPA)]·H2O}n (2), {[Cd2(TTPA)2(TPA)2(DMF)]·2H2O}n (3), and {[Cd(TTPBDA)(TPA)]0.5·DMF·H2O}n (4). They were successfully synthesized from bi-, tri-, and tetratopic phenylamine derivatives (BTPA = bis(4-(1H-1,2,4-triazol-1-yl)phenyl)amine, TTPA = tris(4-(1H-1,2,4-triazol-1-yl)phenyl)amine, TTPBDA = N4,N4,N4′,N4′-tetrakis(4-(1H-1,2,4-triazol-1-yl)phenyl)-(1,1′-biphenyl)-4,4′-diamine) incorporating a linear terephthalic acid (H2TPA) ligand and Zn(II)/Cd(II) nitrate salts. These transparent crystals present gradually increasing dimensionality and complexity upon extension of the denticity of the phenylamine organic building blocks, as clearly supported by single-crystal X-ray analysis, infrared spectroscopy, elemental analysis, powder X-ray diffraction, and thermogravimetric analysis. Complex 1 shows two-dimensional (2D) threefold-interpenetrating layers (2D + 2D → 2D) with the sql topology that are further formed into a three-dimensional (3D) supramolecular structure by interlayer π···π stacking and hydrogen-bonding interactions. Complex 2 displays 2D layers with the hcb topology that are further assembled into a 3D fourfold-interpenetrating supramolecular framework with the 3,4,4T25 topology by hydrogen-bonding interactions. Complex 3 possesses a fourfold-interpenetrating 3D (3,4,5)-connected architecture with the 3,4,5T86 topology. Complex 4 features an interesting and unusual new self-penetrating (4,6)-connected 3D topological network with the point symbol of (414·8)(66), which contains a fourfold-interpenetrated 3D dia network linked by TPA2– ligands. The results suggest that these diverse coordination networks mainly can be adjusted by the number of 1,2,4-triazole substituents on the aniline backbones and the coordination geometries of the metal ions. Furthermore, the photoluminescence spectra and emission decay lifetimes of complexes 1–4 were examined.

•Two new Cd/Zn coordination polymers were constructed.•The metal ions play an important role for the constructions 1 and 2.•1 and 2 exhibit very highly sensitive and selective detection of picric acid compared to other nitroaromatic explosives.Two new coordination polymers, {[Cd(BIDPT)(oba)]·0.5H2O}n (1) and {[Zn(BIDPT)(4,4′-sdb)]·2.25H2O}n (2) (BIDPT = 4,4′-bis(imidazol-l-yl)diphenyl thioether, H2oba = 4,4′-oxydibenzoic acid, 4,4′-H2sdb = 4,4′-sulfonyldibenzoic acid), have been solvothermally synthesized and characterized. Both 1 and 2 show 2-fold interpenetrating 3D frameworks with {65 ∙ 8} cds and {66} dia topology, respectively. These two coordination polymers show strong luminescence and their luminescence could be quenched by a series of nitro explosives. Importantly, they exhibit very highly sensitive and selective detection of picric acid compared to other nitro explosives.Two new 2-fold interpenetrating Cd/Zn metal–organic frameworks show strong luminescence and their luminescence could be quenched by a series of nitroaromatic explosives. They exhibit very highly sensitive and selective detection of picric acid compared to other nitroaromatic explosives.

We developed a novel efficient tridentate anchoring group which can anchor dyes onto the TiO2 surface via synchronously choosing Lewis acid sites and Brønsted acid sites of TiO2. For the purpose of comparing the traditional carboxylate anchoring group to picolinic acid, two new D–π–A porphyrin dyes (JA1 and JA2) differing only in anchoring groups have been synthesized and applied in dye-sensitized solar cells. Picolinic acid as an anchoring group in the dye JA2 not only extended the scope of the spectral response, but also improved the charge transport properties and enhanced the electron injection efficiency. The PCE of the JA1 based-device (carboxylate as the anchoring group) was 5.76%. The PCE of the JA2 based-device was 7.20%, which increased by 25% compared with JA1. The dye TTR2 was used as a cosensitizer; it would not just make up for the poor absorption of porphyrin dyes in the 470–550 nm range, but also would suppress the main dye aggregation and reduce the charge recombination rate. We found that the picolinic acid anchor was more suitable for the cosensitization system than the carboxylate anchor, for there was almost no competitive adsorption between JA2 and TTR2. The JA2 + TTR2 based-device showed the highest PCE of 8.98% under AM 1.5 G irradiation.

Two luminescent Zn(II) metal–organic frameworks were prepared from a π-conjugated thiophene-containing carboxylic acid ligand. These two MOFs show strong luminescene and their luminescence could be quenched by a series of nitroaromatic explosives. Importantly, they exhibit very highly sensitive and selective detection of picric acid compared to other nitroaromatic explosives.

A rare chiral 3D cluster–organic framework {[Zn17O5(NTB)6(NDB)3]·41H2O}n (1) (H3NTB = 4,4′,4′′-nitrilotrisbenzoic acid and H2NDB = 4,4′-nitrilodibenzoic acid) was prepared and structurally characterized. Complex 1 contains two types of [Zn4(μ4-O)(COO)6] and unreported [Zn9(μ3-O)3(COO)12] SBUs, which link bi- and tri-carboxylic acids and extend to an unprecedented (3,6,12)-connected framework. In addition, electronic structure calculations were performed to scrutinize the features of embedded clusters.

The herein obtained multifunctional compound is a promising fluorescent material that can give tunable fluorescence emissions by changing the solvent molecules. The fluorescence sensing behaviors are different for non-protonic and protonic solvents. To date, such a large response range of emission positions for fluorescent MOFs has not been reported before.

Three different Co-MOFs, [Co3(L)2(DPDP)]n (1), [Co(HL)(DPDP)]n (2) and {[Co(HL)(1/2DPDP)3(H2O)]·H2O}n (3) (H3L = 4,4′,4′′-(nitrilotris(methylene))tribenzoic acid, DPDP = 4,4′-(2,5-dibutoxy-1,4-phenylene)dipyridine) have been co-crystallized in a one-pot reaction. Based on the significant differences between the three structures, we adopt solvents to ultimately regulate acquisition of pure crystals of the three compounds.

Three new Co-based MOFs with a nanosized tetradentate pyridine ligand, N,N,N′,N′-tetrakis(4-(4-pyridine)-phenyl) biphenyl-4,4′-diamine (TPPBDA) and carboxylate co-ligands, [Co(TPPBDA)(NO3)2]n·2H2O (1), [Co2(TPPBDA)(bpdc)2 (H2O)]n·2DMA (2) and [Co(TPPBDA)0.5(hfipbb)(H2O)]n·3.5H2O (3) (H2bpdc = biphenyldicarboxylic acid, H2hfipbb = 4,4′-(hexafluoroisopropylidene)bis-(benzoic acid), DMA = N,N-dimethylacetamide) have been synthesized under hydrothermal conditions. For complex 1, a large cavity causes a 4-fold interpenetration of the network, which can be classified as a type IIIa mode of interpenetration. Complex 2 reveals a non-interpenetrating three-dimensional (3D) framework based on the [Co2(μ2-H2O)(CO2)2] unit. Complex 3 is also a 2-fold interpenetrating 3D net based on the [Co2(CO2)2] cluster. These mononuclear or dinuclear cluster units are interconnected by TPPBDA and carboxylate co-ligands, resulting in interesting structural diversities and various degrees of interpenetration.

Chiral coordination polymers have attracted much attention due to their special properties and significant applications. In this work, we synthesized two non-centrosymmetric ligands, N,N-bis(4-(1H-imidazol-1-yl)phenyl)-4-(pyridin-4-yl)aniline (DIMPPA) and N-(4-(1H-imidazol-1-yl)phenyl)-4-(pyridin-4-yl)-N-(4-(pyridin-4-yl)phenyl)aniline (MIDPPA), via structural modification of two reported centrosymmetric ligands; after that achiral → chiral induction occurred in the construction of three coordination polymers namely {[Cd(DIMPPA)(5-OH-bdc)](H2O)}n (1), {[Co(DIMPPA)(5-OH-bdc)](H2O)}n (2) and {[Cd2(MIDPPA)2(D-ca)2(H2O)2](H2O)5}n (3), when replacing the reported centrosymmetric ligands with non-centrosymmetric ligands (5-OH-H2bdc = 5-hydroxyisophthalic acid, D-H2ca = D-camphoric acid). Isostructural complexes 1 and 2 exhibit chiral 2D → 3D frameworks with the coexistence of polyrotaxane and parallel polycatenation features. Complex 3 shows two-fold interpenetrating 3D chiral architecture with cds-type topology. The luminescence emissions of both complexes 1 and 3 are mostly assignable to the internal π→π* electron transition in DIMPPA and MIDPPA, respectively. Complex 3 can satisfy the fundamental requirement of second-order nonlinear optical materials.

Metal–organic frameworks (MOFs) have emerged as an important family of compounds that have fascinating structures and diverse applications. But until now, targeted synthesis of MOFs with desired frameworks is still a challenge. In order to appreciate the properties and to design new frameworks, it is necessary to understand how to rationalize the design and synthesis of MOFs from a fundamental perspective. This highlight review will outline the recent advances in this topic from both our and other groups and provide an overview of the different factors influencing the structures of MOFs. These examples illustrate some of the present trends concerning the design of organic ligands and SBUs, coordination assemblies, and experimental conditions.

Five new metal–organic frameworks (MOFs), {[Zn2(BPPA)2(BDC)2]·6H2O}n (1), {[Cd3(BPPA)(BDC)2(DMF)2]·DMF·3H2O}n (2), {[Zn(BPPA)(NDC)1/2(HCO2)]}n (3), {[Zn3(BPPA)3(TFBDC)3]·H2O}n (4), and {[Cd2(BPPA)2(TFBDC)2]}n (5), have been synthesized from the self-assembly of the “V-shape” BPPA ligand with Zn/Cd metal salts, incorporating coligands (H2BDC = 1,4-benzenedicarboxylic acid, H2NDC = 2,6-naphthalenedicarboxylic acid, TFBDC = 2,3,5,6-tetrafluoroterephthalic acid, BPPA = bis(4-(pyridine-4-yl)phenyl)amine, DMF = N,N-dimethylformamide). Compound 1 is a 4-fold interpenetrated three-dimensional (3D) network with sra topology. Compound 2 is the first 2-fold interpenetrated sxa topology, which is reported only non-interpenetration before. Compound 3 is a one-dimensional chain by utilizing a “longer” rigid H2NDC coligand. Via a “fatter” rigid TFBDC ligand, we control interpenetration by one-pot synthesis. Both compounds 4 and 5 are non-interpenetrated 3D 6T8 frameworks, and the 6T8 topology has rarely been reported in MOFs before. Interestingly, carboxyl groups in 1–5 adopt various coordinate modes. Luminescent properties of 1–5 have also been explored, and the emission decay lifetimes of 4 and 5 are longer than compounds 1–3 and free ligands because of a fluorescent synergistic effect. This may provide an feasible way to exploit materials with long emission decay lifetimes.

Two new D–π–A zinc porphyrin dyes with thiophene and furan π-bridges have been synthesized and employed in dye-sensitized solar cells (DSSCs). Here, the triphenylamine (TPA) moiety was used as the electron donor, and the hexylthiophene chromophores were introduced onto the donor groups, which effectively extended the π-conjugation system. Although the two dyes had similar molecular structures, there was a significant difference between their optical and photoelectric properties. The EIS analysis suggested that the dye with the thiophene π-bridge had a lower charge recombination rate compared to the dye with the furan π-bridge. Based on their light-harvesting abilities, the power conversion efficiency (PCE) of dye JP-S was higher than that of dye JP-O. The JP-S-based DSSC showed a PCE of 5.84%, whereas the PCE of the JP-O-based DSSC was 4.68%. Moreover, using the dye TTR1 as a co-sensitizer made up for the poor absorption of porphyrin dyes in the 480–600 nm range and reduced the charge recombination. The JP-S + TTR1-based DSSCs showed a higher PCE of 6.71%, and the Jsc and Voc values of the device were both increased using this strategy.

Six new cobalt(II) metal–organic frameworks, {[Co1.5(TTPA)(BTC)(H2O)]2·13H2O}n (1), [Co(TTPA)(PA)]n (2), {[Co(TTPA)(BDA)0.5(NO3)]·3H2O}n (3), {[Co2(TTPA)3(OBA)2(H2O)3]·2CH3CN·4H2O}n (4), {[Co(TTPA)(AIP)(H2O)]·2H2O}n (5), and {[Co(TTPA)(MIP)(H2O)]·2H2O}n (6), have been prepared by the self-assembly of a tris(4-(1H-1,2,4-triazol-1-yl)phenyl)amine (TTPA) ligand with different aromatic carboxylate auxiliary ligands (H3BTC = 1,3,5-benzenetricarboxylic acid, H2PA = phthalic acid, H2BDA = (1,1′-biphenyl)-4,4′-dicarboxylic acid, H2OBA = 4,4′-oxydibenzoic acid, H2AIP = 5-aminoisophthalic acid, H2MIP = 5-methylisophthalic acid) and cobalt salts. Their structures have been characterized by infrared spectroscopy, elemental analysis, single crystal X-ray analysis, and powder X-ray diffraction. Complex 1 is an unusual 4-nodal (3,3,4,8)-connected three-dimensional (3D) new topological net with the point symbol of (4·6·8)4(44·67·815·102)(62·84). Complex 2 has a 2-fold interpenetrating 3D dia framework. Complex 3 displays a rare binodal (3,4)-connected 4-fold interpenetrating 3D architecture with a fsc-3,4-C2/c topology with the point symbol of (4·6·8)(4·62·83). Complex 4 shows two distinct two-dimensional (2D) layers with hcb topologies, which are further packed into a 3D structure by O–H⋯O hydrogen bonding interactions. Both complexes 5 and 6 feature similar 2D sheets with sql topologies, which can be further packed into a 3D structure by O–H⋯O hydrogen bonding interactions. Moreover, the thermal stability and UV-visible spectra of these complexes are also discussed in detail. Meanwhile, the variable-temperature magnetic susceptibility measurement of complex 1 reveals antiferromagnetic interactions between Co(II) ions.

Five new cobalt(II) coordination architectures, {[Co(L)2(H2O)2]·2H2O·2NO3}n (1), {[Co(L)(ppda)]·2H2O}n (2), {[Co2(L)(ppda)2]2·H2O}n (3), {[Co(L)(nba)]·5H2O}n (4), and {[Co(L)(oba)]2·3H2O}n (5), have been constructed from the rigid ligand L [L = 2,8-di(1H-imidazol-1-yl)dibenzofuran] and different flexible carboxylic acid ligands [H2ppda = 4,4′-(perfluoropropane-2,2-diyl)dibenzoic acid, H2nba = 4,4′-azanediyldibenzoic acid, and H2oba = 4,4′-oxydibenzoic acid]. Depending on the nature of the solvent systems, these five different coordination polymers were synthesized and characterized by single-crystal X-ray diffraction, IR, PXRD and elemental analysis. Compounds 1, 2 and 3 were obtained by a one-pot method, and then we utilized the solvent-induced effect to obtain almost pure crystals of 1–3, respectively. Compound 1 is an infinite 1D chain which is formed by L ligands and Co atoms. Compound 3 contains a [Co2(CO2)4] secondary building unit (SBU), and can be topologically represented as a 6-connected 2-fold interpenetrating pcu net with the point symbol of {412·63}. Compound 4 can be characterized as a 4-connected sql tetragonal planar network with the point symbol of {44·62}. In compounds 2 and 5, there is a 1D chain which is formed by flexible carboxylic acid ligands and Co atoms; then the 1D chain is linked by L ligands in the tilting direction, leading to the formation of a 2D layer. Furthermore, UV-vis, TGA and magnetic properties have been investigated in detail.

Four coordination polymers with different metal ions have been synthesized based on a rigid linear pyridine and a flexible V-shaped dicarboxylate ligand (L = 4,4′-(2,5-dimethoxy-1,4-phenylene)dipyridine; H2OBA = 4,4′-oxydibenzoic acid): {[Co(L)(OBA)]·2H2O}n (1), [Zn(L)(OBA)·2H2O]n (2), {[Ni(L)(OBA)]·DMF·H2O}n (3), [Cd(L)(OBA)]·DMF·H2O}n (4). The reaction conditions are similar except for the metal ions for complexes 1–4. Complexes 1 and 2 present a 3D unprecedented hxg-d-4-Cccm net, but 3 and 4 are 4-connected sql nets with a point symbol {44·62}. These complexes were characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction measurements. The UV–visible spectra, fluorescence, and gas adsorption properties of the compounds were also explored.

A series of new metal–organic frameworks (MOFs) based on a triangular tri(4-pyridylphenyl)amine (TPPA) ligand that possess novel structures and features, namely [Co2(TPPA)2(1,3-bdc)2(H2O)]n (1); [Zn(TPPA)(1,3-bdc)]n (2); [Zn6(TPPA)2(betc)(Hbetc)2(H2betc)(H2O)6·7H2O·2DMA]n (3) and [Cu(TPPA)(NO3)2(H2O)]·2H2O]n (4) (1,3-H2bdc = 1,3-benzenedicarboxylic acid, betc = 1,2,4,5-benzenetetracarboxylic dianhydride), have been synthesized under solvothermal conditions. In our work different MOFs were synthesized from different metal ions and in different solvents, leading to a variety of coordination modes and structures. In addition, the photochemical properties of compounds 1–4 and the ligands in the solid state were studied.

Solvothermal reactions of 3,5-bis(4-pyridyl)-pyridine (BPYPY) with 1,4-benzenedicarboxylate (1,4-bdc) and trans-1,4-cyclohexanedicarboxylic acid (trans-chdc) in the presence of Co(II) and Ni(II) salts in DMF/H2O or DMA/CH3CN/H2O produced three new compounds, namely, {[Co3(BPYPY)2(1,4-bdc)3(H2O)6]}n (1), {[Ni3(BPYPY)2(1,4-bdc)3(H2O)6]}n (2), {[Co(BPYPY)(trans-chdc)0.5(NO3)]·(H2O)}n (3). These compounds were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Compounds 1 and 2 are isomorphous and present 3,4-connected 3-fold interpenetrating tfz network with a point symbol of {63}2{64·8·10}3. Compound 3 exists binuclear Co clusters which are linked by BPYPY and trans-chdc to generate a 4-connected cds network with the point symbol of {65·8} and displays antiferromagnetic characteristics. In addition, the thermal stabilities of these new compounds have also been discussed in detail.

This paper focuses on the structure modification of triphenylamine dyes for efficient dye-sensitized solar cells (DSSCs). Three D–D–π–A dyes (TTR1–3), with triphenylamine moiety and its derivatives as the electron donor, thiophene ring as the π-bridge, and 2-(1,1-dicyanomethylene)rhodanine (DCRD) as the electron acceptor, were synthesized and fully characterized. Nanocrystalline TiO2-based DSSCs were fabricated using these dyes to investigate the effect of different donor groups introduced into triphenylamine on their photovoltaic performances. The overall power conversion efficiency (PCE) of DSSCs based on TTR1–3 with chenodeoxycholic acid (CDCA) coadsorbant are 5.20%, 5.71% and 6.30%, respectively, compared to 6.62% achieved with N719. Introduced heterocyclic group with alkyl lain into triphenylamine decreased dye absorbed amount but significantly improved the value of the open circuit voltage (Voc) and the short-circuit photocurrent (Jsc), which result from the fact that they can effectively suppress the charge recombination and prevent aggregation between adjacent molecules on TiO2. We also researched the effect of sensitization for single dyes on their photovoltaic performances. The PCEs of DSSCs soaked for 32 h increase slightly compared to those of DSSCs soaked for 16 h, which result from the adsorption quantity on the TiO2 surface. We found that, with soaking twice in 32 h, the Jsc and Voc were both obviously improved compared with soaking once in 32 h. These results provide a new approach for enhancing the photovoltaic performances of DSSCs based on single dye.

•A new 3D Cu(II) coordination polymer with thiophene-containing ligand has been synthesized.•The 3D 2-fold interpenetrating framework shows {44.66} sqp topology, containing interesting ⋯LRLR⋯ double helical chains.•The compound 1 exhibits semiconductive property with a band gap of 2.46 eV.Hydrothermal reaction of Cu(NO3)2·3H2O with BIBP and H2hfipbb at 105 °C yielded a novel 3D Cu(II) coordination polymer, {[Cu2(BIBP)0.5(hfipbb)2(CH3CN)]·5H2O}n (1) [BIBP = 5,5′-bis(1H-imidazol-1-yl)-2,2′-bithiophene, H2hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid)]. Compound 1 displays a 3D 2-fold interpenetrating framework with {44.66} sqp topology, containing interesting ⋯LRLR⋯ double helical chains. The compound 1 was characterized by IR spectra, elemental analysis, thermal analysis and single crystal X-ray diffraction. In addition, solid-state UV–vis spectra experiment shows that compound 1 exhibits semiconductive property with a band gap of 2.46 eV.A new 2-fold interpenetrated 3D Cu(II) coordination polymer {[Cu2(BIBP)0.5(hfipbb)2(CH3CN)]·5H2O}n with thiophene-containing ligand has been synthesized. The compound exhibits {44.66} sqp topology containing interesting ⋯LRLR⋯ double helical chains and shows semiconductive property.

•Two coordination compounds with desymmetric carboxylate and neutral nitrogen ligands have been synthesized.•The dihedral angles for desymmetric carboxylate ligand can tinily adjust to meet the requirement of coordination.•The result of SHG measurements revealed that compound 2 has a SHG response.Two coordination polymers based on a flexible desymmetric ligand precursor H2L have been synthesized, that is, [Ni(L)(dpe)3/2] H2O (1), [Ni2(H2O)(L)2(bpp)2] H2O (2), [H2L = 4,4′-(phenylazanediyl)dibenzoic acid, dpe = 1,2-di(pyridin-4-yl)ethane, bpp = 1,3-di(pyridin-4-yl)propane]. These complexes were characterized by elemental analysis, IR spectroscopy, X-ray single-crystal and power diffraction. In addition, the second nonlinear optical properties of 2 were measured.The solvothermal reactions afford two coordination polymers from a novel desymmetrized ligand, which was derived from the reported N,N,N′,N′-benzidinetetrabenzoic acid.

A series of novel panchromatic D–D–π–A porphyrin dyes have been synthesized and applied to dye-sensitized solar cells. Three porphyrin dyes named JP1, JP2 and JP3, and their photophysical and electrochemical properties and photovoltaic performance were investigated and compared with reference dye YD2-O-C8. 2-Hexylthiophene chromophores were introduced to the donor groups, which extended the π-conjugation system effectively, then broadened the range of spectral response and improved the charge separation between the donor and acceptor moieties in the excited state. Moreover, this paper used thiophene-2-carboxylic acid instead of the traditional benzoic acid as an anchor group, which can make the molecules arrange to tilted orientation when adsorbed on the TiO2 surface, and this may effectively suppress the dye aggregation and prevent charge recombination. These dyes were clearly red-shifted when compared with dye YD2-O-C8. Especially for dye JP3, its maximum absorption peak was red shifted 20 nm with respect to dye YD2-O-C8 from 645 to 665 nm, and the molar extinction coefficient (6.2 × 104 M−1 cm−1) of JP3 is double that of YD2-O-C8 (3.1 × 104 M−1 cm−1) at the Q band. Dye JP3 extended the spectral response to 750 nm. The density functional theory (DFT) calculations indicated that the electronic density of the HOMO was increased by the additional thiophene units in these dyes when compared with YD2-O-C8, and this will improve the conjugation and electron donating ability. The power conversion efficiencies of JP1, JP2 and JP3 are 5.09%, 5.62% and 6.40% respectively under AM 1.5G irradiation, which are 74.5%, 82.3% and 93.7% of the YD2-O-C8 based-device (6.83%) under the same conditions.

Dye-sensitized solar cells (DSSCs) have been considered as very promising third generation solar cells. Porphyrins are promising candidates as highly efficient sensitizers for DSSCs because of their superior light-harvesting ability in the visible region and their mimicking of photosynthesis. This paper focuses on the structure modification of porphyrin dyes for efficient DSSCs, which was based on a rational design using density functional theory (DFT) before the experiment. We synthesized and fully characterized four porphyrin dyes, named ZLD13, ZLD14, ZLD15 and ZLD16. On one hand, we used 5-ethynylthiophene-2-carboxylic acid to replace 4-ethynylbenzoic acid as the electron-withdrawing anchoring group for the first time. Property studies indicate that the aggregation of porphyrin molecules can be sufficiently suppressed via this modification. On the other hand, 4,4′-di(2-thienyl)triphenylamine moiety, which has been proved to be a electron donor group for triarylamine dyes in our previous reports, was introduced to porphyrin dyes, and energy conversion efficiencies (η) were improved by 76% (ZLD15 vs. ZLD13). After the two modifications, the energy conversion efficiency (η) of ZLD16 is comparable with an N719-based reference cell under the same conditions. Enhancement of photovoltaic performances from ZLD13 to ZLD16 is partly due to the decreased dark current and charge recombination rate.

The solvothermal reactions of 1,1′-oxybis[3,5-di-4-pyridine]-benzene (L) and transition metal cations (Co and Ni) afford five novel coordination polymers in the presence of flexible bridging ligands (4,4′-H2nba = 4,4′-dicarboxydiphenylamine, H2cam = D-camphoric acid, 4,4′-H2sdb = 4,4′-sulfonyldibenzoic acid, H2chdc = 1,4-trans-cyclohexanedicarboxylic acid), namely {[Co2L2(OH)2(nba)]·2DMF}n (1), {[CoL(cam)(H2O)]}n (2), {[Co3(L)(4,4′-sdb)3(H2O)]·1.5CH3CN·4H2O}n (3), {[Ni3(L)(4,4′-sdb)3(H2O)]·1.5CH3CN·4H2O}n (4), and {[Ni2L2(chdc)2(H2O)2]·(H2O)3}n (5) (DMF = N,N-dimethylformamide). Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectroscopy, and powder X-ray diffraction. Complex 1 reveals a 2-fold interpenetrating three-dimensional (3D) framework with the Schläfli symbol {4·8·104}{4·8·10} topology. Compound 2 crystallizes in the achiral space group with the D-camphorate ligand racemized. Compounds 3 and 4 reveal similar structure with the {3·44·6}{32·48·59·69} topology based on a linear trinuclear building block M3(OOCR)6 (M = Co(II) or Ni(II)). Compound 5 is a wavy sheet, where both carboxylate and L ligands act as bidentate ligands. Moreover, UV-Visible absorption spectra of complexes 1–3, 5 and the magnetic properties of 3 have been investigated.

Assembly of the 4-connected building units leads to three three-dimensional frameworks, {[Cd(TPPBDA)(OH)2]·2H2O·4DMA}n (1), {[Cd(TPPBDA)1/2(tpdc)]·DMF}n (2), and {[Zn(TPPBDA)1/2(bpdc)]·3H2O·3DMF}n (3) (TPPDBA = N,N,N′,N′-tetrakis(4-(4-pyridine)-phenyl) biphenyl-4,4′-diamine, H2tpdc = 4,4″-dicarboxyl-(1,1′,3′,1″)-terphenyl), H2bpdc = biphenyldicarboxylic acid, DMF = N,N-dimethylformamide, DMA = N,N-dimethylacteamide), which are based on different ratios of tetrahedral (T) and square-planar (S) building units. For compound 1, T and S nodes are in the ratio of 1:1, which is the feature of pts. While T/S is 2:1 in compound 2 to form a bbf framework, for compound 3, the TPPBDA ligand and the metal center are both in tetrahedral configuration, which constructs a dia net with the ratio of 2:0 (T/S). In addition, the compound 2 exhibits high selectivity for CO2 over CH4, showing a hysteretic sorption–desorption loop.

Two rigid linear ligands with alkoxy functional groups (L1 = 4,4′-(2,5-dimethoxy-1,4-phenylene) dipyridine; L2 = 4,4′-(2,5-diethoxy-1,4-phenylene) dipyridine) incorporating carboxyl-containing auxiliary ligands (isophthalic acid = H2IPA; terephthalic acid = H2TPA; biphenyl-4,4′-dicarboxylate = H2BPDC) have been adopted to build a series of complexes with M(II) (M = Zn, Co, Cd) under solvothermal conditions. The formula of these complexes are {[Zn(L1)(IPA)]}n (1), {[Zn(L1)(TPA)]·DMF}n (2), {[Co(L1)(TPA)(H2O)2]·2DMF}n (3), {[Cd(L1)(TPA)(H2O)2]·2DMF}n (4), and {[Co(L2)(BPDC)]·0.5H2O}n (5). Five complexes have been characterized by elemental analysis, infrared spectroscopy, powder X-ray diffraction and thermogravimetry measurements. Topological analyses reveal that complex 2 is a 6-connected pcu net with point symbol {412·63}, while complex 5 is a 6-connected rob net with point symbol {48·68·8}, the other complexes 1, 3, and 4 can be simplified as 4-connected sql nets with point symbol {44.62}. Complexes 1, 3, and 4 are 2D layer motifs, 2 and 5 are both 2-fold interpenetrating 3D frameworks. The optical absorption spectra of 3 and 5 indicate the nature of semiconductivity. The strong fluorescence emissions and long emission lifetimes of 1, 2, and 4 display that they are promising phosphorescent materials.

A new 2-fold interpenetrated cadmium metal–organic framework {[Cd2(TPPBDA)(OBA)2]·4DMA·8H2O}n (1) (Cd-MOF) (TPPBDA = N,N,N′,N′-tetrakis(4-(4-pyridine)-phenyl)biphenyl-4,4′-diamine, H2OBA = 4,4′-oxybis(benzoate), and DMA = N,N-dimethylacetamide) was synthesized by a solvothermal reaction. Compound 1 is a 3D net with a meso-helical chain. A noticeable structural feature is that the arrangement of lattice DMA molecules is different in the different meso-helical channels. The material exhibits gas sorption properties for CO2, H2, and CH4. The adsorption selectivity of CO2/CH4 was calculated from the single-component isotherms using the dual-site Langmuir–Freundlich-based ideal adsorbed solution theory. In addition, the luminescent properties of the Cd-MOF in the solid state and in suspension in different organic solvents was investigated.

Four coordination polymers, namely, {[Cd(L)(BIP)]·3H2O}n (1), {[Co(L)(BIBP)(H2O)4]·4H2O}n (2), {[Ni(L)(BIBP)(H2O)2]·2DMF}n (3), [Ni(L)(BIMB)(DMF)(H2O)]n (4), have been synthesized based on a rigid linear carboxylate ligand (H2L = 2′,5′-dimethoxy-[1,1′:4′,1′′-terphenyl]-4,4′′-dicarboxylic acid) and different lengths of imidazole ligands (BIP = 1,4-di(1H-imidazol-1-yl)benzene; BIBP = 4,4′-di(1H-imidazol-1-yl)-1,1′-biphenyl; BIMB = 4,4′-bis((1H-imidazol-1-yl)methyl)-1,1′-biphenyl). These complexes have been characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction measurements. Complex 1 is a 6-connected 3-fold interpenetrating pcu net with the point symbol {412·63}, 2 is a 1D supramolecular chain-like structure, 3 and 4 can be simplified as 4-connected sql nets with the point symbol {44·62}. In addition, UV-visible spectra and photoluminescent properties are also investigated in detail.

A nonplanar tetrahedral pyridine ligand has been synthesized and applied to assemble five metal–organic frameworks (MOFs) with novel structural features under solvothermal conditions, namely, {[Cu2(TPOM)(adi)2](H2O)4}n (1), {[Zn2(TPOM)(glu)2](H2O)8}n (2), {[Cd2(TPOM)(1,4-chdc)2(H2O)4](H2O)4}n (3), {[Ni(TPOM)(suc)(H2O)2](H2O)2}n (4), and {[Zn2(TPOM)(1,4-chdc)(NO3)2](H2O)2}n (5) (TPOM = tetrakis(4-pyridyloxymethylene)methane, adi = adipic acid, glu = glutaric acid, chdc = 1,4-cyclohexanedicarboxylic acid, suc = succinic acid). These compounds were characterized by elemental analyses, IR spectroscopy and X-ray single-crystal diffraction. Compounds 1 and 3 reveal 3-fold interpenetrating 3D frameworks with sqc969 and new topologies, while compound 2 possesses a 2-fold interpenetrating 3D framework with qtz topology. Compound 4 exhibits a non-interpenetrating 3D structure with the extension of the cage structure, in which there are only two pyridine nitrogen atoms in TPOM involved in the coordination. It is different from compounds 1–3, which may take distinct coordination modes under different conditions. In compound 5, the coordination mode of TPOM is also different from those of compounds 1–3; it is a 2D structure with a 2-fold interpenetrating framework.

A series of new metal–organic frameworks (MOFs), namely, {[Co(BIBP)(hfipbb)]}n (1), {[Co(BIBP)(Hbtc)]}n (2), {[Zn(BIBP)(5-OH-bdc)]}n (3), {[Cd(BIBP)(bdc)]}n (4), {[Zn2(BIBP)0.5(hfipbb)2]·H2O}n (5), {[Zn4(BIBP)4(bdc)4]}n (6), {[Zn(BIBP)(DL-ca)]·H2O}n (7), (BIBP = 5,5′-bis(1H-imidazol-1-yl)-2,2′-bithiophene, H2hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid), H3btc = 1,3,5-benzenetricarboxylic acid, H2bdc = isophthalic acid, 5-OH-H2bdc = 5-hydroxyisophthalic acid, D-H2ca = D-camphor acid), have been hydrothermally synthesized. These compounds were structurally characterized by IR spectroscopy, elemental analysis and X-ray single-crystal diffraction. Compound 1 exhibits a 2D → 3D framework with an unusual parallel polycatenation of corrugated 2D (4,4) nets. Compounds 2–4 are structurally similar and display 2D layer structures, in which 2 and 3 extend into 3D supramolecular frameworks through interlayer O–H⋯O hydrogen-bonding interactions. Compound 5 displays a 3D 2-fold interpenetrating framework with a rare {44·66} sqp topology, containing an interesting ⋯LRLR⋯ double helical layer structure. Compound 6 is a 2D network with {44·62}-sql topology and further extends via C–H⋯O hydrogen bonds into the 3D supramolecular framework. Compound 7 possesses a rare 3D non-interpenetrated cds-type framework with the Schläfli symbol {65·8}. Thermal stabilities for 1–7 and photoluminescence properties of the compounds 3–7 have been examined in the solid state at room temperature. Furthermore, solid-state UV–vis spectroscopy experiments show that compounds 1–7 exhibit optical band gaps which are characteristic for optical semiconductors, with band gaps of 2.41, 2.44, 2.48, 2.46, 2.83, 2.68, and 2.72 eV, respectively.

Six novel metal–organic frameworks (MOFs) have been synthesized in this paper, which are based on a N-centered ligand TPPA, namely, [Cd(TPPA)(fuma)]n (1), {[Zn(TPPA)(suc)]·5(H2O)·DMA}n (2), [Co(TPPA)(bhf)]n (3), [Zn(TPPA)(bhf)]n (4), [Co(TPPA)(oba)]n (5), and [Cd(TPPA)(oba)]n (6), [TPPA = tri(4-pyridylphenyl)amine, H2fuma = fumaric acid, H2suc = succinic acid, H2bhf = 2,2′-bis(4-carboxyphenyl)hexafluoropropane, H2oba = 4,4′-oxybis(benzoic acid)]. Compound 1 reveals a 4-fold interpenetrating 3D framework with AFUQOH topology. Compound 2 reveals a 2-fold interpenetrating 3D network with large void space (up to 37.6%). Compounds 3 and 4 are isomorphic 2D networks. Different from compounds 3 and 4, compounds 5 and 6 show 2D → 3D parallel polycatenation of undulated square layers. In addition, photochemical properties of compounds and the ligands in the solid state have been studied.

Five new metal complexes, {[Ni(DIDP)(m-bdc)(H2O)]·5H2O}n (1), {[Zn(DIDP)(hfipbb)]·2DMA}n (2), {[Zn(DIDP)(4,4′-sdb)]·H2O}n (3), {[Co(DIDP)(p-bdc)]}n (4), and {[Co2(DIDP)(hfipbb)2]·H2O}n (5), have been synthesized by reactions of the corresponding metal ions with a V-shaped ligand 2,8-di(1H-imidazol-1-yl)dibenzothiophene (DIDP) and different aromatic dicarboxylic acids, namely isophthalic acid (m-H2bdc), terephthalic acid (p-H2bdc), 4,4′-(hexafluoroisopropylidene)bis(benzoic acid) (H2hfipbb), and 4,4′-sulfonyldicarboxylic acid (4,4′-H2sdb), respectively. The structures of the complexes were determined by X-ray single-crystal diffraction. Complex 1 is a 1D chain structure containing a one-dimensional channel along the a direction and is further extended via O–H⋯S hydrogen bonds and C–H⋯π stacking interactions into a 3D framework. Complex 2 exhibits a quasi 2D + 2D → 2D with parallel polycatenation of 2D (4, 4) nets. Complex 3 displays an unusual 2D + 2D → 3D parallel polycatenated framework based on a 2D 63-hcb network. Complex 4 shows a 2D 4-connected {44·62}-sql network containing a one-dimensional channel along the b direction. The adjacent 2D networks are further extended via C–H⋯O hydrogen bonds into a 3D supramolecular framework. Complex 5 features a 2-fold interpenetrating 3D framework with a 6-connected {412·63} pcu topology. Furthermore, the thermal stability for 1–5 and luminescence properties of 2 and 3 have been studied. Moreover, the solid-state UV-visible spectroscopy experiments show that complexes 1–5 are all optical semiconductors with band gaps of 3.06, 3.18, 3.23, 2.98, and 3.17 eV, respectively.

•A new coordination polymer with a bifunctional ligand has been synthesized.•The 2-fold interpenetrating 3D framework shows rutile {4·62}2{42·610·83} topology.•The optical properties have been investigated.One new 2-fold interpenetrating three-dimensional (3D) compound with rutile {4·62}2{42·610·83} topology, [Co2(L)2]·DMF·6H2O (1) (H2L = 4,4′-((4-(pyridin-4-yl)phenyl)azanediyl)dibenzoic acid, DMF = N,N-dimethylformamide) has been synthesized under hydrothermal condition. The compound 1 was characterized by IR spectra, thermal analysis and single crystal X-ray diffraction. In addition, UV–Visible spectra of compound 1 are also depicted.One new 2-fold interpenetrated three-dimensional compound [Co2(L)2]·DMF·6H2O with a pyridine-carboxylate bifunctional ligand has been synthesized. The compound contains rutile {4·62}2{42·610·83} topology.

A unique supramolecular helix assisted by solvent molecules (water and DMF) is obtained from an achiral flexible V-shaped ligand, and spontaneous symmetry breaking occurs in crystallization. Notably, the compound displays strong second-harmonic generation (SHG) response.

A highly connected 3D metal–organic framework with tfz-d topology based on Zn6O2 clusters and flexible carboxylate ligands has been synthesized. The obtained Zn-MOF shows solvatochromic behavior for fluorescence sensing of small molecules, gas adsorption properties and exceptional chemical stability and might have applications for separation and detection purposes.

Dye-sensitized solar cells (DSSCs) are currently under intense academic and industrial investigations, because of their environmentally-friendly, efficient, and low-cost features. The photosensitizer plays a key role in determining DSSCs' performance. The 4,4′-di(2-thienyl)triphenylamine moiety, included in dye TTC102, has been demonstrated before as a novel and efficient electron donor fragment. In this paper, the oversimple π-conjugated bridge of TTC102 was replaced by a 9-ethyl-3,6-di(2-thiophenyl)carbazole moiety. Two new D-D-π-A sensitizers, named TTC104 and TTC105, were synthesized and fully characterized. After anchoring on TiO2 nanoparticle film, the absorption band of TTC104 is broader by 30 nm than that of TTC102. Under AM 1.5G irradiation, the energy conversion efficiency (η) of a DSSC based on TTC104 reaches 6.36%, which is 21.6% higher than that of TTC102 (5.24%). The results above demonstrate that the photovoltaic performance can be improved after introducing the 9-ethyl-3,6-di(2-thiophenyl)carbazole moiety to TTC102 when employed in DSSCs. Dye TTC105, containing a pyridyl group as the electron acceptor, showed only 1.88% conversion efficiency (η) when used in DSSCs. The huge different performances of TTC104 and TTC105 are proved to be partly due to the smaller dye loading amount, higher dark current and charge recombination rate of TTC105.

A unique homochiral metal–organic framework has been successfully synthesized by solvothermal reaction of an achiral flexible V-shaped ligand and a nanosized π-electron-deficient pyridine ligand based on cobalt(II) salt, [Co(L)(DPNDI)0.5]n (1) (H2L = 4,4′-dicarboxydiphenylamine, DPNDI = N,N′-di-(4-pyridyl)-1,4,5,8-naphthalenediimide); the helixes assembled by H2L and cobalt(II) paddle-wheel centers are left-handed and transform the framework to chiral. Also, the inserting of the DPNDI transforms the original dia net constructed by H2L and cobalt(II) paddle-wheel centers to a 3-fold jsm net. This is the first example of interpenetrated jsm net. In addition, the chiral property of bulk products is confirmed by circular dichroism spectra (CD), and the thermal stability and the magnetic properties are also investigated.

The reactions of a semirigid tripodal carboxylic ligand, 3,5-bi(4-carboxy-phenoxy)-benzoic acid (H3BCPBA) with Cd(NO3)2/Mn(NO3)2 afford five novel complexes, {[Cd3(BCPBA)2·(DMA)2·(H2O)5]·7H2O·2DMA}n (1), {[Cd3(BCPBA)2(L1)(H2O)6]·(L1)}n (L1 = 4-[(E)-4-pyridinylazo]pyridine) (2), {[Cd3(BCPBA)2(L2)·(H2O)3(DMF)2]·2DMF}n (L2 = 1,3-bis(4-pyridyl)propane) (3), {[Mn3(BCPBA)2(H2O)4]·11H2O}n (4), {[Mn3(BCPBA)2(DMF)2(H2O)2]·2DMF·9H2O}n (5) in the presence or absence of an auxiliary ligand. Compound 1 is a three-dimensional (3D) structure with 3,4-connected net structure. Compound 2 possesses 3D networks with two 3D → 3D interpenetration frameworks. Compound 3 is a 3D sheet structure with a decorated tfz-d topology. Compound 4 is a 3D structure which consists of a two-dimensional (2D) Mn honeycomb net with six infinite Mn rings and BCPBA3– ligands. Compound 5 is also a 3D structure, while its 2D Mn honeycomb net with eight infinite Mn rings is different from that of compound 4. The photochemical property of 1–3 is performed in the solid state at room temperature. Magnetic susceptibility measurements indicate that compounds 4 and 5 exhibit antiferromagnetic coupling between adjacent Mn(II) ions.

Five new metal–organic frameworks incorporating the angular tetratopic ligand with different transition metal ions and bent coligands have been synthesized: [Zn4(L)2(4,4′-sdb)4(H2O)2]·3H2O (1), [Zn2(L)2(hfipbb)2(H2O)3] (2), [Zn(L)(oba)]·H2O (3), [Cd2(L)2(4,4′-sdb)2]·2H2O (4), [Cd2(L)(hfipbb)(H2O)3]·2H2O (5), [L = 1,1′-oxybis[3,5-dipyridine-benzene, 4,4′-H2sdb = 4,4′-sulfonyldibenzoate, H2hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid), H2oba = 4,4′-oxybis(benzoate)]. Structural analysis reveals that the mixed ligands display versatile coordination modes to manage the metal ions to form homochiral, inclined polycatenation (1D → 2D), 3-fold interpenetrating nets. However, the different coordinated modes, geometry, and flexibility of ligands around metal ions result in subtle differences in the final architecture. Bulk materials for 1 and 3 have a second-harmonic generation activity, approximately 0.4 and 0.8 times that of urea.

Six new metal–organic frameworks with novel structural features based on a star-like ligand tri(4-pyridylphenyl)amine (TPPA), namely, {[Cd(TPPA)(pht)(H2O)](H2O)2}n (1), {[Zn(TPPA)(pht)](H2O)2}n (2), {[Zn(TPPA)(trans-chdc)0.5(NO3)]·(H2O)}n (3), {[Co(TPPA)(bdc)(H2O)]·(H2O)}n (4), {[Co(TPPA)(bdc)(H2O)]·(H2O)4}n (5), and {[Co(TPPA)(bdc)]}n (6) (H2pht = phthalic acid, trans-H2chdc = trans-1,4-cyclohexanedicarboxylic acid, H2bdc = benzene-p-dicarboxylic acid), have been synthesized under solvothermal conditions. Compounds 1–3 all exhibit fascinating 2D → 3D frameworks with coexistence of inclined polycatenation and polythreading characters. On the other hand, compounds 4–6 are three supramolecular isomers. Even though the compositions of 4–6 are almost same, they generate different structures. Compound 4 shows a 2D → 3D framework with parallel polycatenation of undulated square layers. Compound 5 reveals 3-fold interpenetrating 3D frameworks with {4.62}{43.67} crs topology. Compound 6 shows a 4-fold interpenetrating 3D metal–organic polyrotaxane framework. In addition, photophysical properties of 1–3 and the TPPA ligand in the solid state have also been studied.

Five chiral and noncentrosymmetric metal–organic frameworks, namely, {[Co(TIPA)(trans-chdc)(H2O)]·H2O}n (1), {[Ni(TIPA)(trans-chdc)(H2O)]·H2O}n (2), {[Co(TIPA)(seb)1/2](NO3)·H2O}n (3), {[Ni(TIPA)(seb)1/27](NO3)·H2O}n (4), and {[Zn2(TIPA)(btc)(μ2-OH)]·4H2O}n (5), have been synthesized based on the N-center tripodal TIPA ligand, where TIPA is tris[4-(1H-imidazol-1-yl)-phenyl]amine, H3btc is 1,3,5-benzenetricarboxylic acid, trans-H2chdc is trans-1,4-cyclohexanedicarboxylic acid, and H2seb is sebacic acid. Complexes 1 and 2 are isostructural, crystallize in the chiral orthorhombic space group P212121, and contain a 2D → 3D parallel/parallel inclined subpolycatenation based on (6,3) layers. The two sets of layers of subpolycatenation are interconnected by right-handed Co(trans-chdc) helical chain, forming a self-catenated framework. Complexes 3 and 4 are also isostructural and crystallize in the chiral monoclinic space group C2. They also contain a 2D → 3D parallel/parallel inclined subpolycatenation based on (6,3) layers. Complex 5 crystallizes in the noncentrosymmetric space group Pna21. Similarly to complexes 1–4, it also contains a 2D → 3D parallel/parallel inclined subpolycatenation based on (6,3) dinuclear Zn-TIPA layers. Meanwhile, the btc3– ligand with a trimonodentate coordination mode connects the dinuclear Zn unit to form a 2D (6,3) Zn-btc layer. The combination of the two types of interconnected 2D nets results in a self-catenated framework. SHG measurements on complexes 1–5 reveal that complexes 1 and 2 display modest SHG responses that are approximately 3 and 4 times that of KH2PO4 (KDP). The SHG responses of 3 and 4 are about the same as those of 1 and 2, respectively. Complex 5 has a strong SHG response, and its SHG efficiency is approximately 10 times that of KDP. In addition, the photoluminescent properties and thermal stabilities of these complexes were studied in the solid state.

Three fascinating coordination polymers, {[Zn2(TPPBDA)(HCO2–)4]·2H2O}n (1), {[Zn(TPPBDA)1/2(4,4′-sdb)]·2H2O }n (2), and {[Zn(TPPBDA)1/2(oba)·2DMF·2H2O]}n (3), have been successfully synthesized and characterized by the self-assembly of the TPPDBA ligand as well as Zn2+ metal salts, or in the presence of carboxylate ligands (TPPDBA = N,N,N′,N′-tetrakis(4-(4-pyridine)-phenyl) biphenyl-4,4′-diamine), 4,4′-H2sdb = 4,4′-sulfonyldibenzoate, 4,4′-H2oba = 4,4′-oxybis(benzoate), DMF = N,N-dimethylformamide). In complex 1, the 2D ABAB parallel stacked network in which left- and right-handed helical chains coexist and array alternately (2Dchiral/2Dchiral → 2Dachiral) makes 1 give rise to a new interesting 2D interwoven network. Complex 2 exhibits a 2D + 2D → 2D parallel interpenetrated network. For compound 3, the polycatenation among the 2D layer further extends the 2D net into a 3D framework.

Six new metal–organic frameworks (MOFs), namely, {[Cd(BPBP)0.5(hfipbb)]·0.5DMF}n (1), {[Zn(BPBP)0.5(hfipbb)]}n (2), {[Co(BPBP)0.5(hfipbb)·0.5DMF]}n (3), {[Zn(BPBP)(trans-chdc)]·H2O}n (4), {[Zn2(BPBP)(4,4′-sdb)2]}n (5), and {[Zn2(BPBP)(oba)2]·H2O·DMA}n (6) (BPBP = 5,5′-bis(4-pyridyl)-2,2′-bithiophene, H2hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid), trans-H2chdc = trans-1,4-cyclohexanedicarboxylic acid, 4,4′- H2sdb = 4,4′-sulfonyldicarboxylic acid, H2oba = 4,4′-oxybis(benzoic acid), DMF = N,N-dimethylformamide, DMA = N,N-dimethylacetamide), have been hydrothermally synthesized. These compounds were characterized by IR spectroscopy, elemental analysis and X-ray single-crystal diffraction. Compounds 1–3 are isostructural and display 3D 2-fold interpenetrating frameworks with rare {44.610.8} mab topologies. Compound 4 exhibits a 3D diamond-type (dia, 66) framework of 6-fold interpenetration. Compound 5 shows a 2D network with {44·62}-sql topology, which consists of 1D [Zn2(4,4′-sdb)2]n chains. Compound 6 possesses a 3-fold interpenetrating 3D framework with 6-connected {412·63} pcu topology. Magnetic studies reveal that compound 3 exhibits antiferromagnetic behavior. Thermal stabilities for 1–6 and photoluminescence properties of the compounds 1, 2, 4, 5, and 6 have been examined in solid states at room temperature. Furthermore, the UV–vis absorption spectra and optical energy gap of 3 were also investigated.

The self-assembly reaction of a multinodal preformed cluster with 1,2-di(pyridin-4-yl)ethane as the organic ligand afforded the 2D cluster polymer (1), {[(WS4Cu4)I2(dpe)2](DMF)4}n. There is a cavity between each two nearby dpe ligands in 1. The [WS4Cu4]2+ units are fixed by I− ions, which is attributed to the multinodal feature of the W–S–Cu secondary building units, and therefore, the cavities in 1 are settled. The NLO properties show that 1 exhibits an optical self-focusing behavior and reverse saturable absorption effects. This work provides us with useful clues to further explore the 2D W–Cu–S-based cluster polymer with cavities.

Three heterothiometallic cluster–organic nanospheres have been synthesized and characterized. They own identical cationic cluster–organic nanoball frameworks and show selectivity towards charge-balancing anions. It is also interesting that the morphology of the as-prepared particles can be tuned by simply varying the polarity of the solvent.

Five new metal–organic frameworks have been synthesized under hydrothermal conditions, in CH3CN–H2O, DMF–CH3CH2OH–H2O and DMA–H2O, namely, [ZnL(bimx)0.5]n (1), {[CoL(4,4′-bipy)]·DMF}n (2), {[CdL(4,4′-bipy)]·DMF}n (3), {[ZnL(bibp)]·DMA·(H2O)2}n (4), {[CoL(bpyb)0.5]·(H2O)2}n (5) (bimx = 1,4-bis(imidazol-1-ylmethyl)benzene, 4,4′-biby = 4,4-pyridine, bibp = 4,4′-bis(imidazol-1-yl)biphenyl, bpyb = 1,4-bis(4-pyridyl)benzene, H2L = 4,4′-(phenylazanediyl)dibenzoic acid. These complexes were characterized by elemental analysis, IR spectroscopy, TG and X-ray single-crystal diffraction. In compounds 1, 2 and 3, the bimx, 4,4′-bipy and L2− anions act as bidentate ligands assembling with metal cations to form two-dimensional (2D) sheets. The sheets are stacked in ABAB fashion and accumulate into a 3D framework. Compound 4 possesses a 3D→3D 4-fold interpenetrating architecture with {65·8} topological net, which is similar to the cds topology. Compound 5 also displays a 3D structure with {44·610·8} topology. The photochemical properties were investigated in the solid state at room temperature. The luminescent properties of compounds 1, 3 and 4 are discussed in detail. The UV-vis absorption spectra of compounds 2 and 5 are tested and discussed. In addition, the magnetic properties of compound 5 also are tested and simply analyzed.

Three MOFs including novel architectural features were synthesized via one-pot reaction. Reaction time, temperature and ratio of ligands were found to influence the formation of the three compounds and we obtained conditions to synthesize the three MOFs in purely individual phase directly.

•A new Mn coordination polymer with mixed-ligands has been synthesized.•The 3D framework was proved by single-crystal X-ray diffraction.•Title polymer can be simplified α-Po pcu net with topology symbol {412⋅ 63}.One new title compound [Mn3(BIBP)(sdb)(NO2−)2(H2O)2]n·2DMF (1) (BIBP = 4,4′-bisimidazolylbiphenyl, sdb = 4,4′-sulfonyldibenzoic acid) has been synthesized under hydrothermal condition. The title compound was characterized by IR spectra, thermal analysis, single crystal and powder X-ray diffraction. Magnetic susceptibility measurements indicate that compound 1 exhibits antiferromagnetic coupling interaction.One new compound [Mn3(BIBP)(sdb)(NO2−)2(H2O)2]n·2DMF has been synthesized under hydrothermal condition. The compound has an interesting 3D architecture which can be simplified α-Po pcu net with topology symbol {412⋅ 63}

Flexible carboxylic ligands have attracted considerable interest due to their excellent stretchable capacity and coordinative ability. In this paper, one new 2D zinc coordination polymer {[Zn(tcpob)2/3(H2O)2/3]·(H2O)2/3}n with trinuclear zinc cluster units was prepared under hydrothermal conditions based on 1,3,5-tri(4-carboxyphenoxy)benzene ligand. In addition, the solid-state photoluminescent spectra were measured at room temperature.Self-assembly of a triangle flexible carboxylic acid and Zn salt under solvothermal conditions generated a new 2D coordination polymer with trinuclear zinc cluster units.Highlights► Triangle flexible carboxylic ligand acts as the bridging ligand. ► Characterization by elemental analysis, IR, PXRD and X-ray crystallography. ► AB stacking structure including trinuclear zinc cluster units. ► Emission of the complex is attributed to charge transfer of internal ligand.

One new title compound [Cu2(TPOM)(adi)2]n · 4nH2O (1) (TPOM = tetrakis(4-pyridyloxymethylene)methane, adi = adipic acid) has been synthesized under hydrothermal condition. The title compound was characterized by IR spectra, thermal analysis, single crystal and powder X-ray diffraction.One new compound [Cu2(TPOM)(adi)2]n · 4nH2O has been synthesized under hydrothermal condition. The compound has a 3-fold interpenetrating 3D architecture.Highlights► A new Cu coordination polymer with mixed-ligands has been synthesized. ► The 3D framework was proved by single-crystal X-ray diffraction. ► Title polymer is an interesting 3-fold interpenetrated 3D structure.

•V-shaped ligand acts as the bridging ligand.•The two coordination polymers are stacked 2Dchiral/2Dchiral → 2Dachiral sheets.•Emissions are attributed to the ligand-to-metal charge-transfer transitions.Two new stacked 2Dchiral/2Dchiral → 2Dachiral coordination polymers {[Cd(BIDPE)(pim)]·(H2O)}n (1) and {[Cd(BIDPE)(glu)]·(H2O)}n (2) were prepared under hydrothermal conditions based on V-shaped ligand 4,4′-bis(imidazol-1-yl)diphenyl ether (BIDPE) and flexible polycarboxylic acids. In addition, the solid-state photoluminescent spectra were measured at room temperature.Two new stacked 2Dchiral/2Dchiral → 2Dachiral coordination polymers were synthesized based on V-shaped imidazolyl ligand and flexible polyaliphatic acids.

•A new Co coordination polymer with mixed-ligands has been synthesized.•The 2D framework was proven by single-crystal X-ray diffraction.•Title compound exhibits antiferromagnetic coupling between adjacent Co(II) ions.One new title compound [Co(BIBP)(mpa)]n (1) (BIBP = 4,4′-biimidazole biphenyl, mpa = m-phthalic acid) has been synthesized under solvothermal condition. The title compound was characterized by IR spectra, thermal analysis, single crystal and powder X-ray diffraction. The results prove that the alliance of BIBP and aromatic carboxylic acids is good for diversity of the getatable structure. Magnetic susceptibility measurements indicate that compound 1 exhibits antiferromagnetic coupling between adjacent Co(II) ions. In addition, the photochemical properties have been investigated.One new title compound [Co(BIBP)(mpa)]n has been synthesized under solvothermal condition. Magnetic susceptibility measurements indicate that compound exhibits antiferromagnetic coupling between adjacent Co(II) ions.

Three supramolecular isomers, {[Cd2(TPOM)(hfipbb)2]·x/y/zsolvent}n (1–3), have been synthesized and characterized by one-pot reaction. Even though the compositions of 1–3 are the same, they generate different structures. Reactions over various time periods were found to influence the formation of supramolecular isomers, and there is little influence on this system under other conditions.

Two supramolecular isomers, {[Co(L)(OBA)]·H2O}n (1), {[Co5O2(L)2(OBA)3]·7DMF}n (2), have been synthesized by one-pot reactions. Compound 1 has a homochiral architecture with low connectivity, and compound 2 is an achiral 3D framework with high 12-connectivity. It is unprecedent to get homochiral and achiral supramolecular isomers by one-pot synthesis.

Three new metal–organic frameworks (MOFs) are designed by the assembly of flexible V-shaped ligands and paddle-wheel second building units (SBUs). The topology, interpenetration numbers and porosity of frameworks have been well controlled by a solvent system.

The first luminescent metal–organic framework (MOF) with [Zn6(μ6–O)] cluster has been synthesized and realized for reversible sensing of small molecules.

The solvothermal reaction of two new neutral tetradentate ligands with different bivalent metal salts gave seven metal–organic frameworks (MOFs): [Co2(L1) (trans-chdc)2]·5H2O (1), [Zn2(L1)(trans-chdc)(NO2)2]·DMF (2), [Cd2(L1)(trans-chdc)2]·4H2O (3), [Zn2(L1)(1,4-bdc)2]·(H2O)3 (4), [Cd2(L1)(1,4-bdc)2]·DMF·(solvent)x (5), [Co(L2) (trans-chdc)(H2O)]·1.5H2O (6), [Co(L2) (1,4-bdc) (H2O)] · 2H2O (7), (L1 = 1,1′-oxybis[3,5-diimidazole]-benzene, L2 = 1,1′-oxybis[3,5-dipyridine]-benzene, trans-chdc = trans-1,4-cyclohexanedicarboxylic acid, 1,4-bdc = 1,4-benzenedicarboxylate). These MOFs were prepared to examine the effects of the core metal ion or organic ligand on the topology and interpenetration form. The results show that the imidazole ligand can rotate easily to coordinate to metal ions, while pyridine ligand exhibits the weaker coordinative abilities, which may influence the self-assembly. Compounds 1, 3, and 5 are three-dimensional (3D) frameworks with 2-fold interpenetrated forms, whereas complex 4 shows a 3-fold interpenetrated structure. Interestingly, compound 2 exhibits a 4-fold interpenetration. Compound 6 features a two-dimensional polymeric layer structure which exhibits a rare 2-fold interpenetrating 3D hms array if H-bonds are taken into account. For compound 7, the dinuclear cobalt secondary building unit (SBU) assembles with mixed ligands L2 and 1,4-bdc to construct a 3D α-Po structure.

Six new coordination polymers, {[Zn2(DPT)2(btc)(Hbtc)]·2H2O}n (1), {[Cd(DPT)(Hbtc)(H2O)]·4H2O}n (2), {[Co(DPT)(Hbtc)]·1/2DPT}n (3), {[Zn(DPT)(oba)]·11H2O}n (4), {[Co2(DPT)2(oba)2]·DMF·3H2O}n (5), and {[Zn4(DPT)2(bdc)4(H2O)2]·2H2O·DMA}n (6), have been obtained from the self-assembly of the heterocycle ligand DPT with different metal salts, in the presence of coligands (DPT = 2,5-dipyridine-thiophene, H3btc = 1,3,5-benzenetricarboxylate, H2oba = 4,4′-oxybis(benzoate), H2bdc = 1,4-benzenedicarboxylate, DMF = N,N-dimethylformamide, DMA = N,N-dimethylacetamide). Their structures have been characterized by single crystal X-ray analysis. Compounds 1–3 are 2D motifs, of which 1 and 2 are joined via H-bond bridges to give 3D supramolecular architectures. Complex 4 is a 2D network constructed from left- and right-handed helical chains. Complex 5 has a 3-fold interpenetrating 3D pcu framework. Complex 6 features a polycatened structure, which can be parallel/parallel catenated with two other equivalent bilayer ones to form a 2D → 3D framework. The photoluminescence properties of the compounds 1, 2, 4, and 6 have been examined in solid states at room temperature, and they have been found to exhibit yellow photoluminescence. In addition, the UV–visible spectra are also depicted in detail.

Six new metal–organic frameworks, namely, {[Cd(bpbenz)(pim)] }n (1), {[Cd(bpbenz)(sea)]·(H2O)2}n (2), {[Cd(bpbenz)(hfipbb)]·(H2O)3}n (3), {[Co(bpbenz)(4,4′-sdb)]·(H2O)2.75}n (4), {[Ni(bpbenz)(4,4′-sdb) (H2O)3]·(H2O)2}n (5), and {[Co(bpbenz)(Hbtc)]·(H2O) }n (6), [bpbenz = 1,4-bis(4-pyridyl)benzene, pim = pimelic acid, sea = sebacylic acid, H2hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid), 4,4′-sdb = 4,4′-sulfonyldibenzoate, H3btc = 1,3,5-benzenetricarboxylate, and DMF = N,N-dimethylacetamide], have been synthesized under hydrothermal conditions. These compounds were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Compound 1 is a 3D network composed of layers of pentagonal-bipyramidal coordinated Cd atoms bridged by pimelic anions in syn–anti configurations and bpbenz molecules between layers with {412.63} pcu topology. In compound 2, the bpbenz and sebacylic anions act as bidentate ligands assembling with Cd(NO3)2 to a 2D framework. Compound 3 is a 2D network composed of chains, which is bridged by the [Cd2(CO2)4]2L2 SBUs and hfipbb2- anions, and with bpbenz molecules between chains. For compound 4, the bpbenz and 4,4′-sdb coordinate to Co cations to form a three-dimensional{65.8} cds uninodal network. Compound 5 features 2D structure with inclined polycatenation (1D + 1D → 2D). For compound 6, a 2D network with side arms leads to the formation of a polythreaded network, which exhibits a 2-fold interpenetrating 3D array if H-bonds are taken into account. Magnetic susceptibility measurements indicate that compounds 4 and 6 have dominating antiferromagnetic couplings between metal ions. Furthermore, thermal stabilities for 1–6 and luminescent properties for 1–3 are also discussed in detail.

Three-fold dendrites of Ce(OH)CO3 with multilayer caltrop have been synthesized on a large scale by means of a complexing agent assisted solution route. The shape of these as-prepared architectures can be tuned effectively by controlling the reaction conditions, such as reaction time and the molar ratio of complexing agent/Ce3+. As a typical morphology, the growth process of 3-fold dendrites of Ce(OH)CO3 with multilayer caltrop has been examined, and a possible mechanism is discussed. The phase and morphology of the as-prepared product have been characterized by means of powder X-ray diffraction (XRD), (high resolution) transmission electron microscopy (HRTEM), and scanning electron microscopy (SEM). The morphology of dendrites is sustained after thermal decomposition–oxidation Ce(OH)CO3 to CeO2. To extend this method, La(OH)CO3 and Eu3+/Ce(OH)CO3 dendritic structures can also be achieved at similar reaction conditions. After similar heat treatment in an oven, their dendritic structures are also retained. La(OH)CO3 completely transforms into La2O2(CO3), and Eu3+/Ce(OH)CO3 changes to Eu3+/CeO2. The photoluminescent properties of Eu3+/Ce(OH)CO3 and Eu3+/CeO2 dendrites have also been investigated. This work sheds some light on the design of well-defined complex nanostructures.

Five new complexes of the wholly deprotonated C-centered triangular flexible ligand tris(p-carboxyphenyl)methane (TCOPM), namely, {[Zn4O(TCOPM)2(H2O)2]·8H2O·3DMF}n (1), {[Mn3(TCOPM)2(H2O)2]}n (2), {[Cd3(TCOPM)2(DMF)(H2O)3]·3H2O}n (3), {[Cd3(TCOPM)2(4,4′-bipy)]·2H2O·2DMF}n (4), and {[Cd4(TCOPM)2(dpyb)3(NO2)2·(H2O)2]·5H2O}n (5), are synthesized in the presence or absence of auxiliary 4,4′-bipyridine (4,4′-bipy) and 1,4-di(pyridine-4-yl)benzene (dpyb) ligands by solvothermal reaction. The complexes were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and X-ray single-crystal diffraction. Compound 1 exhibits an unusual three-dimensional (3D) framework containing a one-dimensional (1D) channel based on a Zn4O cluster, with (4·82)(42·6)(43· 6· 810·10) net topology. 2 displays a 3D network structure with tfz-d topology type. Compound 3 reveals double-layered two-dimensional (2D) framework. Compound 4 possesses a 3D structure with a (3,3,10)-connected net. 5 is a 3D structure with (623·85)(63)2(65·8) topology. The photochemical properties and emission decay lifetimes were determined in the solid state at room temperature. The luminescent properties of compounds 1 and 3–5 are discussed in detail. The N2 gas adsorption of compound 1 exhibits type-I sorption behavior.

Six new compounds of partially or wholly deprotonated 3,5-bi(4-carboxy-phenoxy)-benzoic acid (H3BCPBA), namely, {[Co(H2BCPBA)2(H2O)4]}n (1), {[Co(HBCPBA)(bipy0.5)2·(H2O)]}n (bipy = 4,4′-bipyridine) (2), {[Co3(BCPBA)2(dpe)·(μ2-H2O)4]·2H2O·2DMF}n (dpe = 1,2-di-4-pyridyleth-ene) (3), {[Co3(BCPBA)2(pdp)·(μ2-H2O)4]·2DMF}n (pdp = 4-[(E)-4-pyridinylazo]pyridine) (4), {[Co3(BCPBA)2(bpe)·(μ2-H2O)4]·2DMF}n (bpe = 1,2-bis(4-pyridyl)ethane) (5), {[Co2(HBCPBA)2 (bpp)·(μ2-H2O)2]·H2O·2DMF}n (bpp = 1, 3-bis(4-pyridyl)propane) (6) were synthesized in the presence or absence of auxiliary ligand. Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectroscopy, and thermogravimetric analysis. Compound 1 is a zero-dimensional structure. Compound 2 is a two-dimensional (2D) sheet structure with two 2D → 2D interpenetration frameworks. Compounds 3–5 are similar and possess three-dimensional (3D) networks with two 3D → 3D interpenetration frameworks. In compound 6, H3BCPBA and bpp ligands link Co centers to generate a 2D sheet structure which is further connected by intermolecular hydrogen bonds to form a 3D supramolecular structure. The photochemical properties are performed in the solid state at room temperature. Magnetic susceptibility measurements indicate that compounds 2–6 exhibit antiferromagnetic coupling between adjacent Co(II) ions.

Solvothermal reactions of 4,4′-dicarboxydiphenylamine (H2L) with 4,4′-bis(imidazol-1-yl)phenyl (BIP) and 4,4′-bis(imidazol-1-yl)diphenyl (BIBP) in the presence of cobalt(II), cadmium(II), zinc(II) salts in H2O/CH3CN or H2O/DMF produced five new complexes, namely, [Co2(L)2(BIP)2·3H2O]n (1), [Co(L)(BIP)·2CH3CN]n (2), [Co(L)(BIBP)·H2O]n (3), [Cd(L)(BIBP)]n (4), [Zn(L)(BIBP)]n (5). Compound 1 has binuclear Co(II) clusters, which are linked by L2– and BIP to generate a rare three-dimensional (3D) non-interpenetrated cds-type framework, and displays ferromagnetic character. Compound 2 possesses unusual 3-fold 2D → 2D polycatenation of (4, 4) nets. Compound 3 reveals a (4, 4) grid topology with very strong hydrogen bondings due to the abundant uncoordinated carboxyl groups, which load in the structure like a freely dangling arm. Compound 3 also displays weak ferromagnetic character. Compounds 4 and 5 are isomorphic. H2L and BIBP ligands in 4 and 5 interact with a metal center to form wave-like 2D sheets. In addition, the thermal stabilities and photochemical properties of compounds have been studied.

Solvothermal reactions of CuSO4·6H2O and Cu(Ac)2·H2O with 3,6-di-2-pyridyl-1,2,4,5-tetrazine (DPTZ) in the presence of different acetonitrile/water ratios (from 1:3 to 3:1) and temperatures (from 40 to 120 °C) successfully produce five coordination polymers: [Cu4(SO4)2(H2O)5(L2)2] (1), [Cu2SO4(H2O)3(L2)] (2), [Cu2(μ-CN)2(L1)] (3), [Cu2(bdc0.5)2(L2)(H2O)] (4, H2bdc = p-phthalic acid) and [Cu(L3)2] (5) (the known mononuclear compound). Unexpectedly three ligands: 2,5-bis(2-pyridyl)-1,3,4-oxodiazole (L1), N-bis-(R-hydroxyl-2-pyridyl)ketazine (H2L2) and pyridine-2-carboxylate (HL3), were obtained through NN bond cleavage of DPTZ. Complexes 1, 2 and 3 own one-dimensional (1D) structures, complex 4 shows a two-dimensional (2D) framework. The new compounds were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. We focus our study on the ring-opening reaction mechanism, the occurrence process of CuII → CuI, the C–CN cleavage reaction of acetonitrile under lower temperatures (40–60 °C) and the influence of temperature and the ratio of solvent. In addition, magnetic susceptibility measurements indicate that 1, 2 and 4 show strong antiferromagnetic interactions between the adjacent CuII ions.

The solvothermal reaction of a neutral tetradentate ligand, different bivalent metal salts and two rigid carboxylate co-ligands gave six metal–organic frameworks (MOFs): [Zn(L)(Hbdc)(bdc)0.5]·1.5H2O (1), [Zn2(L)(bdc)2(H2O)]·2H2O (2), [Cd(L)(bdc)(H2O)]·2H2O (3), [Ni(L)(bdc)(H2O)]·H2O (4), [Co3(L)(btc)2(H2O)4] (5), [Zn3(L)(btc)2(H2O)4] (6) (L = 1,1′-oxybis[3,5-dipyridine]-benzene, H2bdc = 1,4-benzenedicarboxylate, H3btc = 1,3,5-benzenetricarboxylate). Compounds 1 and 2 have been co-crystallized in a one-pot reaction. In compound 1, L and H2bdc ligands link Zn centers to generate a two-dimensional (2D) sheet structure which is further connected by intermolecular hydrogen bonds to form a 3-fold interpenetrating 3D fsc-3,4-C2/c array. Single crystal X-ray diffraction analysis reveals that compound 2 features a 3D self-interpenetrated network with {4·6·83·10}{4·63·82}{64·82} topology. For compounds 3 and 4, the binuclear metal secondary building unit (SBU) assembles with mixed ligands, L and H2bdc, to construct a 3D α-Po structure. Compounds 5 and 6 are isostructural and show 3-fold interpenetrated pte/Cmmm->P2/c structures.

Four new metal–organic frameworks based on a new star-like ligand tri(4-pyridylphenyl)amine (TPPA), namely, {[Cd(TPPA)(trans-chdc)]}n (1), {[Co(TPPA)2(D-ca)2]·(H2O)}n (2), {[Ni(TPPA)(bdc)(H2O)]·(H2O)4}n (3), {[Ni(TPPA)(trans-chdc)(H2O)]·(H2O)4}n (4), (trans-H2chdc = trans-1,4-cyclohexanedicarboxylic acid, d-H2ca. = d-camphor acid, H2bdc = benzene-p-dicarboxylic acid), have been synthesized under solvothermal conditions. Compound 1 represents the first example of a 4-fold interpenetrating 3D metal–organic polyrotaxane framework, with {42.65.83}{42.6} AFUQOH topology. In 2, each d-ca2– anion links adjacent Co2+ atoms to a 2D framework, and only one N atom from each TPPA ligand is involved in coordination, which should be partly attributed to the weak flexibility of the TPPA ligand. Both 3 and 4 reveal 3-fold interpenetrating 3D frameworks bridged by TPPA ligands and bdc2– (or trans-chdc2–) anions, with {4.62}{43.67} crs topology. In addition, photophysical properties of 1 and the TPPA ligand in the solid state have also been studied.

Solvothermal reactions of tetrakis(4-pyridyloxymethylene)methane (TPOM) with deprotonated isophthalic acid (1,3-H2bdc), 5-hydroxyisophthalic acid (5-OH-H2bdc), benzene-1,3,5-tricarboxylic acid (H3btc), and benzene-1,2,4,5-tetracarboxylic acid (H4btc) in the presence of zinc and cobalt salts produce four new complexes, namely, {[Co2(TPOM)(bdc)2(H2O)2]·(H2O)3}n (1), {[Zn2(TPOM)(5-OH-bdc)2]·(DMF)(H2O)2}n (2), {[Co3(TPOM)(btc)2(H2O)]·(H2O)4}n (3), and {[Zn2(TPOM)(btc)2]n (4). Complexes 1 and 2 possess similar 2-fold interpenetrating three-dimensional (3D) framework with bbf topology, but 1 crystallizes in an achiral space group, and 2 crystallizes in chiral space group and displays ferroelectric behavior. Complex 3 reveals a 3D framework with biunclear Co clusters, which displays weak antiferromagnetic character. In complex 4, only H4btc links Zn(II) to generate a 3D porous framework, with TPOM occupying the void space as countercation and template. In addition, photochemical and ferroelectric properties of these new complexes in the solid state have been studied.

Dye-sensitized solar cells (DSSCs) based on free-standing, double-walled TiO2 nanotubes with bamboo-like morphology have been prepared by a sequence of alternating voltage and two-step anodization treatments. The combination of double-walled and bamboo-like morphologies led to an increase in dye loading and an improvement in photoconversion performance. Subsequently, the fabricated dye-sensitized nanotubes used to prepare DSSCs that operate in a frontside illumination mode yielded a significantly high power conversion efficiency of 3.46%, which was approximately two times higher than DSSCs that were fabricated using traditional single-walled TiO2 nanotube arrays with smooth surfaces. In addition, DSSCs fabricated from nanotubes with higher bamboo ring densities exhibited better conversion efficiencies than those prepared from nanotubes with lower bamboo ring densities. The improved conversion efficiency can be attributed to increased dye loading in the combined double-walled and bamboo-like titania nanostructures.Graphical abstractDye-sensitized solar cells (DSSCs) based on free-standing, double-walled TiO2 nanotubes with bamboo-like morphology have been prepared and investigated. The fabricated DSSCs exhibited a significantly high power conversion efficiency of 3.46%, which was approximately two times higher than DSSCs that were fabricated using traditional single-walled TiO2 nanotube arrays with smooth surfaces.Highlights► Titania nanotubes with double-walled/bamboo structures were used in solar cells. ► Solar cells from double-walled/bamboo nanotubes show good conversion efficiencies. ► The improved conversion efficiency is due to an increase in nanotube-dye loading.

A nanotubular metal−organic framework (MOF), {[(WS4Cu4)I2(dptz)3]·DMF}n (dptz = 3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine, DMF = N,N-dimethylformamide) for sensing small solvent molecules is presented. When accommodating different solvent molecules as guests, the resulting inclusion compounds exhibit different colors depending on the solvent guests, and more interestingly, the band gaps of these solvent-included complexes are in linear correlation with the polarity of the guest solvents. The solvent molecules can be sensed by the changes of UV−vis spectra of the corresponding inclusion compounds, showing a new way of signal transduction as a new kind of sensor. The sensing by such a MOF occurs within the channel-containing material rather than on the external surface.

The self-assembly reaction of the preformed clusters with two extended linear and trigonal rigid ligands as organic linkers afforded two 2D and 3D Mo(W)/Cu/S-based cluster polymers. They show unprecedented structure types in Mo(W)/S/Cu chemistry and exhibit strong third-order nonlinear optical properties.

Solvothermal reactions of 4,4′-bis(imidazol-1-yl)diphenyl ether (BIDPE) with deprotonated 5-hydroxy-isophthalic acid (5-OH-H2bdc), and benzene-1,3,5-tricarboxylic acid (H3btc) in the presence of cadmium(II), zinc(II), cobalt(II), nickel(II), and manganese(II) salts in H2O or H2O/DMF produced six new complexes, namely, [Cd(BIDPE)(5-OH-bdc)·H2O]n (1), [Co(BIDPE)(5-OH-bdc)·H2O]n (2), [Zn3(BIDPE)3(5-OH-bdc)3·4H2O]n (3), [Ni(BIDPE)2(5-OH-bdc)(H2O)·3H2O]n (4), {[Mn2(BIDPE)2(5-OH-bdc)2]n (5), and [Ni(BIDPE)2(Hbtc)(H2O)]n (6). These complexes were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Compounds 1 and 2 reveal the same two-dimensional (2D) sheets with a 32-membered [(Cd/Co)2(BIDPE)2] metallocyclic ring constructed from BIDPE and 5-OH-H2bdc with Cd or Co salts. For compound 3, six identical 2D sheets are polycatenated in parallel to form a rare 2D → 2D framework; it displays ferroelectric behavior with a remnant electric polarization (Pr) of 0.033 μC/cm2 and an electric coercive field (Ec) of 11.15 kV/cm. In compounds 4 and 6, only one carboxyl group coordinated to the Ni atom from 5-OH-H2bdc or H3btc. Compound 5 exists as binuclear Mn clusters, which are linked by BIDPE and 5-OH-H2bdc to generate a 2D sheet and displays weak antiferromagnetic character. In addition, the thermal stabilities and photochemical properties of these new complexes have been studied.

Four cadmium and cobalt coordination polymers with unique structures and topologies have been successfully synthesized under solvothermal conditions by employing an elongated triangular rigid N-containing ligand tris(4-(1H-imidazol-1-yl)phenyl)amine (TIPA) and 5-hydroxyisophthalic acid (5-OH-H2bdc) as anion coligand. Compounds 1−4 were characterized by single crystal X-ray structure analyses, thermogravimetric analyses, SHG, and photoluminescent measurements. Compound 1 crystallizes in the chiral space group C2 (No. 5) and features a 2D → 3D parallel/parallel inclined polycatenated framework. Compound 2 crystallizes in trigonal symmetry with a high-symmetry space group R3̅ and features a 2D porous noninterpenetrating coordination network. Compound 3 crystallizes in the monoclinic space group P21/n and shows a 2D → 3D parallel/parallel polycatenation framework, and compound 4 crystallizes in the orthorhombic chiral space group P212121 (No. 19) and shows a very rarely 3D + 3D heterogeneous 2-fold interpenetration framework built from (3,5)-connected (42·65·83)(42·6) AFUQOH nets and (3,5)-connected (63)(69·8) gra nets.

Five new complexes, namely, {[Zn(L)(L1)]·(H2O)(DMF)2}n (1), {Cd(L)(L1)0.5}n (2), {[Zn2(L)2(L2)2]·DMF}n (3), {[Zn(L)(L3)]·(H2O)5}n (4), and {[Cd2(L)2(L3)1.5(H2O)]2·H2O}n (5), have been synthesized by the solvothermal reaction of 4,4′-(hexafluoroisopropylidene)bis(benzoic acid) (H2L) with different transition metal ions in the presence of ancillary ligands 1,4-bis(imidazol-1-ylmethyl)benzene (L1), 4,4′-bis(imidazol-1-ylmethyl)-biphenyl (L2), and 4,4′-bis(benzimidazol-1-ylmethyl)biphenyl (L3). Complex 1 displays a two-dimensional (2D) framework containing two kinds of ring units. In complex 2, one-dimensional (1D) Cd chains are assembled by L2− and L1 ligands into a non-interpenetrated three-dimensional structure. Complex 3 possesses a 2D framework which is generated by joining both P and M helices by L2− ligands. The structure of 4 is a three-dimensional (3D) framework with {42.6.83} net containing meso-helices, while 5 is a 2D structure with {414.6} net. The photoluminescent properties of 1−5 have been studied in the solid state at room temperature.

Three new isomorphic coordination polymers of Co2+, Zn2+ ions with flexible multicarboxylic acid ligand of the cis,cis,cis-1,2,3,4-cyclopentanetetracarboxylic acid (H4L), [Co4L2(H2O)8]·3H2O (1), [Zn4L2(H2O)8]·3H2O (2) and [Co0.8Zn3.2L2(H2O)8]·3H2O (3), have been synthesized under hydrothermal conditions and by means of controlling the pH of the reaction mixtures (with an initial pH of 6.0 for 1, 4.0 for 2, and 5.0 for 3, respectively). In the crystal of 1, two crystallographically different Co2+ ions (Co1 and Co2) form a negatively-charged coordination polymeric chain, which contains a centrosymmetric, linear, trinuclear Co2+ cluster (Co3L2) subunit; another crystallographically independent Co2+ ion (Co3) coordinated to six water molecules acts as a counter ions to link the neighboring coordination polymeric chains via intermolecular H-bond interactions. The Co2+ ions in 1 were completely and partially replaced by Zn2+ ions to give 2 and 3, respectively. Complex 3 shows a novel molecular alloy nature, due to the random distributions of the Co2+ and Zn2+ ions. Three isomorphic complexes exhibit distinct thermal decomposition mechanisms. The deprotonated cis,cis,cis-1,2,3,4-cyclopentanetetracarboxylic acid ligands decompose at 420–750 °C to give the residue CoO in 1, ZnO + C in 2 and CoO + ZnO in 3. Complex 1 shows a complicated magnetic behavior with co-existence of antiferromagnetic exchange interactions between neighboring Co2+ ions as well as strong spin–orbital coupling interactions for each Co2+ ion; complex 3 exhibits a magnetically isolated high-spin Co2+ ion behavior with strong spin–orbital coupling interactions.

Solvothermal reactions of partially or wholly deprotonated biphenyl-3,4′,5-tricarboxylate (H3L) with nitrates of cadmium, manganese and cobalt, in the presence or absence of auxiliary 4,4′-bipyridine (bipy) and 1-(3,5-di(1H-imidazol-1-yl)phenyl)-1H-imidazole (timp) ligands in H2O–DMF, produce four new complexes, namely, {[Cd3(L)2(H2O)9]·(H2O)5}n (1), {[Cd2(HL)2(timp)(H2O)4]·(H2O)4}n (2), {Mn(HL)(bipy)0.5(H2O)}n (3), {Co(HL)(bipy)0.5(H2O)}n (4). Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra, and thermogravimetric analysis. Complex 1 possesses a three-dimensional (3D) framework composed of two-dimensional (2D) T-shaped molecular bilayer motifs polycatenated with each other. In complex 2, multicarboxylate ligands and timp ligands link Cd centers to generate one-dimensional (1D) ladder structures which are further connected by π–π interactions to form a 3D supramolecular structure. Complexes 3 and 4 are isostructural and possess 2D networks. Magnetic susceptibility measurements indicate that complexes 3 and 4 exhibit ferromagnetic coupling between adjacent Mn(II) ions and Co(II) ions. The photoluminescent properties of 1 and 2 have been studied in the solid state at room temperature.

Two porous (3,4)-connected zinc coordination polymers, {[Zn(TIPA)(mal)1/2](NO3)·3H2O}n (1) and {[Zn(TIPA)(glu)1/2](NO3)·H2O}n (2) (mal = malonic acid, glu = glutaric acid, TIPA = tris(4-(1H-imidazol-1-yl)phenyl)amine) have been hydrothermally synthesized and characterized. Complex 1 crystallizes in the orthorhombic space group Pnna (No. 52) containing an unusual 3D subnet with (10,3)-d topology and left- and right-handed helical channels. Complex 2 crystallizes in the orthorhombic chiral space group P2221 (No. 17) containing an unusual 3D chiral subnet with (10,3)-a topology and 4-fold right-handed helical channels. The conversion of achiral complex 1 with a (10,3)-d (utp) achiral subnet to chiral complex 2 with a (10,3)-a (srs) chiral subnet has been successfully induced by increasing the length of ditopic aliphatic dicarboxylic acid. Second harmonic generation (SHG) measurement was performed on complex 2 revealing that 2 has a strong SHG response, and the SHG efficiency is approximately 0.8 times that of urea (ca. 8 times that of KDP). In addition, photoluminescence and thermogravimetric analysis were also performed on 1 and 2.

Four metal–organic coordination polymers, {[Cu2(4,4′-bibp)2(NO2)3)]·(NO2)(H2O)}n (1), [Cd(bdc)(4,4′-bibp)]n (2), {[Co2(bdc)2(4,4′-bibp)3(H2O)2]·(H2O)2}n (3), [Zn(Hbtc)(1,4-bix)]n (4) (4,4′-bibp = 4,4′-bis(1-imidazolyl)biphenyl; 1,4-bix = 1,4-bis((1H-imidazol-1-yl)methyl)benzene; H2bdc = 1,4-benzenedicarboxylate; H3btc = 1,3,5-benzenetricarboxylate) were obtained under hydrothermal conditions and characterized structurally. X-Ray diffraction analysis reveals that the four complexes exhibit new frameworks due to diverse coordination conformations. In copper compound 1, with mixed-valence copper(II)–copper(I), rigid linear 4,4′-bibp ligands connect two adjacent layers and the whole structure is a three-dimensional 6,6-connected network. In cadmium compound 2, 4,4′-bibp and bdc anions as bidentate ligands coordinate to cadmium cations to form a three-dimensional 4,4-connected network with a 3-fold interpenetrating framework. In cobalt compound 3, 4,4′-bibp and bdc anions also act as bidentate ligands, and coordinate to cobalt cations to form a three-dimensional 4,6-connected network. Zinc compound 4 shows that both the 1,4-bix ligand and btc anions act as bidentate bridging ligands, and connect the zinc cations to give a 2D polycatenated array structure. The magnetic properties for copper compound 1 and luminescent properties for cadmium compound 2 and zinc compound 4 are also discussed in detail.

Three novel metal–organic frameworks, namely, {[(Zn4O)1/2(Zn3–OH)1/2L3/2O1/4(H2O)5/2(NO2)1/2]·(H2O)4}n (1), {[Cd3L2(H2O)4]·(H2O)9·DMA}n (2), and {[Co(HL)(4,4′-bibp)]}n (3; H3L = 5′-carboxyl-[1,1′:3′,1′′-terphenyl]-4,4′′-dicarboxylic acid, 4,4′-bibp = 4,4′-bisimidazolylbiphenyl, DMA = N,N-dimethylacetamide), have been synthesized under hydrothermal conditions. These compounds were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Compound 1 reveals an unusual 3D structure with {4·52}{4·62}{42·52·68·83}{52·6}{53·65·82} topology based on Zn4O and Zn3–OH clusters. In compound 2, the H3L ligand assembles with Cd(NO3)2 to a 3D framework with sqc27 {4·62}2{42·610·83} topology. They are both three-dimensional frameworks containing one-dimensional channels. In compound 3, the HL2– anion and 4,4′-bibp both act as bidentate ligands and coordinate to Co cations to form a three-dimensional 4-connected uninodal network. In addition, the thermal stabilities for 1–3 and luminescent properties for 1 and 2 are also discussed in detail.

Four novel metal coordination polymers, [Zn(2-PBIM)(OH-BDC)]n (1), [Cd(2-PBIM)(OH-BDC)]n (2), [Mn(2-PBIM)(OH-BDC)]n·1.5nH2O (3), [Cu(2-PBIM)(OH-BDC)]n·nH2O (4) [2-PBIM = 2-(2-pyridyl)benzimidazole; OH-H2BDC = 5-hydroxy-1,3-benzenedicarboxylic acid], have been synthesized under hydrothermal conditions and structurally characterized by single crystal X-ray diffraction analysis, elemental analysis, IR spectroscopy, and thermogravimetric analysis. Compound 1 possesses left-handed screw (M-helix) and right-handed screw (P-helix) chains that are further connected though intermolecular hydrogen bonds and π–π stacking interactions resulting in a three-dimensional (3D) network. Compound 2 has a two-dimensional metal-organic framework which is connected into a 3D network by intermolecular hydrogen bonds and π–π stacking interactions. Compounds 3 and 4 are isostructural and possess one-dimensional (1D) channels. Free 2-PBIM and OH-H2BDC ligands and complexes 1, 2 show fluorescent emissions in the visible and near-infrared region. Magnetic susceptibility measurements indicate that both 3 and 4 exhibit antiferromagnetic coupling between adjacent center atoms.Graphical abstractFour novel metal coordination polymers have been synthesized under hydrothermal conditions and structurally characterized by single crystal X-ray diffraction analysis, elemental analysis, IR spectroscopy, and thermogravimetric analysis. Their fluorescent and magnetic properties have also been reported.Highlights► Four novel metal coordination polymers have been synthesized and structurally characterized. ► Free ligands and complexes 1, 2 show fluorescent emissions in the visible and near-infrared region. ► Magnetic susceptibility measurements indicate that both 3 and 4 exhibit antiferromagnetic coupling.

Solvothermal reactions of tetrakis(4-pyridyloxymethylene)methane (TPOM) with deprotonated 1,4-benzenedicarboxylate (H2bdc) or 5-hydroxyisophthalic acid (5-OH-H2bdc) in the presence of nitrates of cadmium, zinc, and cobalt in H2O or H2O/DMF produced five new complexes, namely, {[Cd2(TPOM)(bdc)2]·(H2O)5(DMF)}n (1), {[Zn2(TPOM)(bdc)2]·(H2O)4}n (2), {[Zn2(TPOM)(bdc)2]·(H2O)}n (3), {[Co2(TPOM)(5-OH-bdc)2(H2O)2]·(H2O)5}n (4), and {[Cd2(TPOM)(5-OH-bdc)2]·(H2O)2}n (5). These complexes were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Complex 1 reveals a 2-fold interpenetrating three-dimensional (3D) framework with pcu topology constructed from binuclear Cd clusters and TPOM ligands. In addition, the experiment of single-crystal-to-single-crystal (SC-SC) structural transformations upon guest exchange was tested. Zn complexes 2 and 3 possess different 3D frameworks and are prepared from TPOM and H2bdc under different reaction conditions. In complexes 4 and 5, TPOM and 5-OH-H2bdc link Co or Cd centers to generate 3D interpenetrating frameworks with bbf and qtz topology. In addition, thermal stabilities and photochemical properties of these new complexes in the solid state have been studied.

Eight new coordination complexes, namely [ZnL1(H2O)2]n (1), [CdL1(H2O)2]n (2), [CoL1(H2O)3]n (3), [EuL1(NO2)(H2O)]n (4), [SmL1(NO2)(H2O)]n (5), [CdL2(H2O)]n (6), [CoL2(H2O)4]n (7) and [NiL2(H2O)4]n (8) were synthesized under solvothermal conditions based on flexible ligands 2,2′-(naphthalene-2,7-diylbis(oxy)) diacetic acid (H2L1) and 2,2′-(biphenyl-4,4′-diylbis(oxy)) diacetic acid (H2L2). X-Ray diffraction analysis revealed that the eight complexes exhibited new frameworks due to diverse coordination conformations of the flexible bicarboxylate ligands. In complexes 1–8, H2L1 and H2L2 all acted as bridging ligands to connect the metal ions. Complexes 1 and 2 both exhibited three-demensional (3D) supramolecular structures formed by one-demensional (1D) chains through intermolecular interactions. Complex 3 formed its 3D network by connecting the two-demensional (2D) layers through hydrogen bonds. Complexes 4 and 5 had similar 3D frameworks which are combined by nitroso groups as pillars. Complex 6 represented a 3D framework with pcu α-Po topology by using L22− ligands as linkers and the [Cd2O6] secondary building units (SBUs) as 6-connected nodes. The isostructural complexes 7 and 8 also gave rise to 3D supramolecular networks by joining 1D chains with hydrogen bonds and π–π interactions. The luminescent properties for 1, 2, 4 and 6 are discussed in detail. Complexes 3, 4, 7 and 8 exhibited antiferromagnetic interactions between the magnetic centers.

Five new complexes, [Ln(OABDC)(H2O)5]n·2nH2O [Ln = Sm (1), Eu (2), Dy (3)], [Ni4(OABDC)2(OH)2(H2O)4]n·4nH2O (4), [Cu2(OABDC)(4,4′-bipy)0.5(OH)]n (5) have been synthesized by the hydrothermal reaction of a unique scorpion-shaped carboxylate ligand (5-oxyacetate isophthalic acid = H3OABDC) with different lanthanide or transition metals in the presence or absence of auxiliary 4,4′-bipyridine ligand. Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra, and thermogravimetric analysis. Compounds 1–3 are isostructural: the metal ions are bridged through carboxylate oxygen atoms to form 1D zigzag chains, and adjacent chains are further extended to a 3D supramolecular structure via hydrogen bonds. Compound 4 has a two-dimensional (2D) metal–organic framework based on [Ni4(μ3-OH)2]6+ clusters, which are further connected by intermolecular hydrogen bonds to form a 3D network. In compound 5, multicarboxylate ligands link Cu centers to generate a 2D sheet structure which is further connected by auxiliary 4,4′-bipyridine ligand to form a 3D structure. Free H3OABDC ligand and complexes 1, 2 exhibit strong fluorescent emissions in the visible region. Magnetic susceptibility measurements indicate that 4 exhibits weak ferromagnetic coupling between adjacent Ni(II) ions, whereas 5 shows antiferromagnetic coupling between Cu(II) ions.

Five new coordination compounds, namely [Zn(Hbtc)(1,3-bix)(H2O)]n (1), {Zn2(µ-O)(btc)(timp)]·3(H2O)}n (2), {[Zn3(4,4′-bibp)2(btc)2(H2O)2]·4(H2O)}n (3), {[Ni3(4,4′-bibp)2(btc)2(H2O)2]·3(H2O)}n (4), {[Cu3(4,4′-bibp)2(btc)2(H2O)]·2(H2O)}n (5), where 1,3 - bix = 1- (3 - (1H -inidazol - 1 − yl)methyl)benzyl)-1H-imidazole, timp = 1- (3,5-di (1H-imidazol-1-yl)phenyl)-1H-imidazole, 4,4′-bibp = 4,4′-bisimidazolylbiphenyl, and btc = 1,3,5-benzenetricarboxylate anion, were synthesized under hydrothermal conditions. In compound 1, both 1,3-bix ligand and btc anion act as bidentate bridging ligands, and connect the zinc cations into a one-dimensional chain. In compound 2, timp and btc anions as tridentate ligands coordinate to zinc cations to form a three-dimensional 3,6-connected network. Compounds 3–5 have similar structures, 4,4′-bibp and btc anions act as bidentate and tetradentate ligands, respectively, and coordinate to metal cations to form a three dimensional 4,4-connected network. The luminescence properties for 1–3 and magnetic properties for 4–5 are also discussed in detail.

Six new metal−organic frameworks have been synthesized under hydrothermal conditions, in H2O or DMF/H2O, namely, [CoL]n (1), [Ni2L2(H2O)3]n (2), [CoL(bimx)1/2]n (3), [NiL(bimx)1/2]n (4), [MnL(bimx)1/2]n (5), {[CoL2(bimb)(H2O)2]·2H2O}n (6) (bimx =1,4-bis(imidazol-1-ylmethyl)benzene, bimb =4,4′-bis(imidazol-1-ylmethyl)biphenyl, H2L = 5-(4-pyridyl)-methoxyl isophthalic acid). These complexes were characterized by elemental analysis, IR spectroscopy and X-ray single-crystal diffraction. Complex 1 reveals a 2-fold interpenetrating three-dimensional (3D) framework with rutile {4 · 62}2{42 . 610 . 83} topology. Complex 2 possesses a 3D 4-fold interpenetrating framework with ths topology. In complexes 3, 4 and 5, H2L and bimx ligands link Co, Ni and Mn cations to generate 3D frameworks. Compound 6 possesses a 3D interlocked structure, with 2D structures intercatenating each other into a 3D structure (2D + 2D→3D) and with new topology. In addition, thermal stabilities, photochemical properties, and the magnetic properties for 1, 3, 4, and 5 are also discussed in detail.

Solvothermal reactions of 4,4′-bis(imidazol-1-yl)diphenyl ether (BIDPE) with deprotonated 1,4-benzenedicarboxylic acid (H2bdc) in the presence of cadmium, zinc, cobalt, nickel, and manganese salts in H2O or H2O/DMF yielded six new complexes, namely, {[Co(BIDPE)(bdc)]2·(H2O)2(DMF)}n (1), {[Cd(BIDPE)(bdc)]4·(H2O)4(DMF)2}n (2), {[Zn(BIDPE)(bdc)]2·(H2O)2(DMF)}n (3), [Cd3(BIDPE)2(bdc)3]n (4), and [Ni(BIDPE)(bdc)(H2O)2]n (5), and [Mn(bdc)(BIDPE)(H2O)]n (6). These complexes were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Complexes 1 and 3 reveal a 2-fold interpenetrating three-dimensional (3D) framework constructed from BIDPE and H2bdc with Co and Zn salts; complexes 2 and 4 have the same staring materials but possess different 3D frameworks and are prepared from BIDPE and H2bdc under different reaction conditions. In complexes 5 and 6, BIDPE and H2bdc link Ni and Mn centers, respectively, to generate 2D → 2D interlocked sheets. The thermal stabilities and photochemical properties of these new complexes have also been studied.

Reaction of uranium oxynitrate hexahydrate with 4, 4″-Dicarboxyl-(1,1′,3′,1″)-Terphenyl (H2L) by liquid diffusion method resulted in a complex {[UO2(L)(DMF)]·H2O}n. Single-crystal diffraction analysis shows that the uranyl ion is in a pentagonal bipyramid coordination environment. Five oxygen atoms of L2− ligands and DMF constructed the equatorial plane. Two oxygen atoms of uranyl occupy the two axial positions. The complex got the two-dimensional layered structure by π–π interactions. The thermal analysis verifies the component and the structure of the complex. The UV/vis measurement exhibits that the complex has strong absorption in the UV and visible region.Reaction of uranium oxynitrate hexahydrate with 4, 4″-Dicarboxyl-(1,1′,3′,1″)-Terphenyl (H2L) resulted in the complex [UO2(L)(DMF)]n•nH2O. UV–vis spectroscopic data exhibit that the complex has strong absorption in the UV and visible region.

Three new heterothiometallic cluster polymers with fascinating topologies have been synthesized by the self-assembly of preformed heterothiometallic cluster monomers and appropriate ligands. Reaction of the monomeric cubic-shaped cluster [Et4N]3[MoOS3Cu3I4] with the D2h symmetry rigid bidentate 4,4′-bipy (4,4′-bipyridine) gave a two-dimensional (2D) layer compound [Mo2O2S6Cu6I2(4,4′-bipy)3(H2O)]n (1); the assembly of pentanuclear cluster monomer [Et4N]4[WS4Cu4I6] with Cs-symmetrical bpe (1,2-bis(4-pyridyl)ethane) afforded a 2D layer compound [WS4Cu4I2(bpe)3(H2O)]n (2), and the assembly of heptanuclear cluster monomer [Et4N]4[WS4Cu6I8] with D3h symmetry trigonal planar ligand timtz (2, 4, 6-tri(1H-imidazol-1-yl)-1, 3, 5-triazine) afforded a three-dimensional (3D) compound [WS4Cu6I4(timtz)8/3(H2O)12]n (3). X-ray crystallographic analysis reveals that 1 crystallizes in trigonal space group R3̅c with 2D 36-hxl net which is the first heterothiometallic superamolecular structure based on a twin cubic-shaped cluster monomer and also the first example of 4,4′-bipy-connected compound of this net. 2 crystallizes in tetragonal space group P42 with distorted 2D 36-hxl net which is the first flexible-ligand-based compound of this topology; while 3 has a 3D net with the high symmetry of cubic space group I4̅3d, and has a novel α-C3N4 topology, which is the maximum symmetry for this net topology. The gas sorption isotherm was measured for 3 to exhibit type-III sorption behavior.

The crystallization of 2,3-dihydro-thieno[3,4-b][1,4] dioxine-5,7-dicarboxylic acid (H2tddc) with divalent transitional metal (Co, Ni, Zn, Cd) or with tervalent lanthanide metal (Sm) and with mixed ligand 4,4′-bipyridine (4,4′-bipy) or 1,10-phenanthroline (1,10-phen) formed six new complexes: [Co(C8H4O6S) · 3H2O] (1), [Co(C8H4O6)(1,10-phen)(H2O)] · H2O (2), [Ni(C8H4O6S)(4,4′-bipy)(H2O)] · 3H2O (3) [Sm(C8H4O6S)(NO3)(H2O)4] · 2H2O (4), [Zn(C8H4O6S)(H2O)3] (5), and [Cd2(C8H4O6S)2(4,4′-bipy)2] (6). The structures of these six crystals have been characterized by single-crystal X-ray diffraction analyses, which revealed that complexes 1, 4, 5 are all one-dimensional chain structures and they self-assemble into three-dimensional super-molecules via the hydrogen bond interactions and π–π stacking interactions, 2 is also a one-dimensional chain structure but still self-assembles into one-dimensional double-chains, the complex 3 has two-dimensional undulating parallelogram grid structure extended along the bc-plane, the crystal of 6 is a 3D threefold interpenetration topology framework with 46638 nodes. The photoluminescent properties of the H2tddc ligand and the six compounds have been measured in the solid state at room temperature. Free ligand has no luminescence, while its complexes 1, 4, and 6 all exhibit intense photoluminescence which implies that these complexes may be excellent candidates for potential photoactive materials.The six coordination polymers with H2tddc ligand have been synthesized. Their structures were determined by X-ray diffraction and fluorescent properties have been investigated.

Four new coordination complexes, M2(Htmopa)4(H2O)4 (M = Zn2+ (1), Mn2+ (2), {M(Htmopa)2(H2O)2}n (M = Ni2+ (3), Co2+ (4)), have been synthesized by the hydrothermal reaction of Htmopa (Htmopa = 2,3,6,7-tetramethoxyphenanthrene-9-carboxylic acid) with different transition metals at a suitable temperature. Single-crystal determinations revealed that 1 and 2 are isostructural and possess a dinuclear subunit, each connected into 3D networks by hydrogen bonds and C−H···π interactions. 3 and 4 are also isostructural: the metal ions are bridged through water molecules and carboxylate oxygen atoms to form 1D wavelike double chains, and these double chains are further extended to a 3D network via hydrogen bonds and C−H···π interactions. The photoluminescent properties of the free Htmopa ligand and its complexes have been studied in the solid state at room temperature. Both Htmopa and 1 exhibit strong blue emissions. Magnetic susceptibility measurements indicate that 2 and 3 exhibit antiferromagnetic coupling, whereas 4 shows a ferromagnetic coupling and exhibits a single-ion behavior of the CoII ion at a higher temperature range.

Four new compounds of partially or wholly deprotonated 5,5′-(1,4-phenylenebis(methylene))bis(oxy)diisophthalic acid (H4L1) and 5,5′-(1,3-phenylenebis(methylene))bis(oxy)diisophthalic acid (H4L2), namely {[Co(L1)0.5]·(H2O)2}n (1), {[Mn(L1)0.5]·(H2O)2}n (2), {[Cu(H2L1)](μ2-bipy)}n (bipy = 4, 4′-bipyridyl) (3), and {[Zn2(L2)].H2O}n (4) were synthesized in the presence or absence of auxiliary bipy ligand. Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra, and thermogravimetric analysis. Compounds 1 and 2 are isostructural and possess three-dimensional (3D) networks. In compound 3, multicarboxylate ligands and bipy ligands link Cu centers to generate a two-dimensional (2D) sheet structure which is further connected by intermolecular hydrogen bonds to form a 3D supramolecular structure. In compound 4, the Zn centers are connected by L24− anions to generate a 3D framework. Magnetic susceptibility measurements indicate that compounds 1 and 2 exhibit antiferromagnetic coupling between adjacent Co(II) ions and Mn(II) ions. The photoluminescent properties of the free H4L1 and H4L2 ligands and compound 4 have been studied in the solid state at room temperature. Both ligands and compound 4 exhibit strong violet emissions. Compared with the fluorescent emission of the ligand, the emission of 4 is red-shifted and enhanced.

The self-assembly of 3,5-pyrazoledicarboxylic acid (H3pdc) and metal salts under hydrothermal conditions leads to the formation of a series of novel NaI–CuII–LnIII heterometallic coordination polymers, {[Na(H2O)4]2[Cu(pdc)2Ln(H2O)5]2·3H2O}n [Ln = La (1); Sm (2); Pr (3); Nd (4) and pdc3− = 3,5-pyrazoledicarboxylate]. X-Ray structure analyses show that these complexes all exhibit pairs of infinite, unexpected, cationic and anionic chains. It is the first successful attempt to construct unprecedented NaI–CuII–LnIII heterometallic coordination polymers with both infinite cationic and anionic chains. These four complexes show homologous thermal stabilities. The different magnetic properties of 1–3 are also been reported in this paper.

•Six isomorphous lanthanum coordination polymers were constructed.•The emission of the lanthanides can be sensitized with antenna effect.•Five MOFs show strong luminescence.By using a semi-rigid tripodal ligand 1,1′,1′′-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)tripyridinium-4-olate) (L), six isomorphous lanthanum metal-organic frameworks (MOFs), namely, [Pr(L)2(Cl)2]·(Cl)(DMF)0.5·(H2O)·(1), [Nd(L)2(Cl)2]·(Cl)(2), [Tb(L)2(Cl)2]·(Cl)·(DMF)·(H2O)(3), [Eu(L)2(Cl)2]·(Cl)(DMF)·(H2O)(4), [La(L)2(Cl)2]·(Cl)(5), [Sm(L)2(Cl)2]·(Cl) (DMF)·(H2O) (6), were obtained and characterized by single crystal X-ray diffraction, IR and elemental analysis. Six compounds are isostructural with Ln3 + (Ln = Pr, Nd, Tb, Eu, La, Sm) and in which the Ln3 + is considered as a 6-connecting node and the L ligand is a 3-connecting node to afford a (3,6)-connected 2D layer with kgd topology, which further stacks into 3D supramolecular networks through C-H…O weak interactions. Luminescent properties of these lanthanide MOFs have also been assessed at ambient temperature, in which the Pr3 +-1 and the La3 +-5 are slightly blue-shifted with respect to the ligand. Series of sharp peaks characteristic of the Eu3 +-4, the Tb3 +-3 and Sm3 + − 6 metal-centered luminescence appear. The Nd3 +-2 has no emission.Six compounds show binodal node (3,6)-connected 2D layer with kgd topology. In which five MOFs show strong luminescence, the Pr-1 and the La-5 are slightly blue-shifted with respect to the ligand. Series of sharp peaks characteristic of the Eu-4, the Te-3 and Sa-6 metal-centered luminescence appear.

Herein we prepare four novel D–π–A dyes based on triphenylamine (ZHG1, ZHG2, ZHG3 and ZHG4) by modifying the π-bridges. Compared with ZHG1, the power conversion efficiency (PCE) of ZHG2 is improved to 6.1% after the introduction of ethynyl. But further extension of the conjugation of the π-bridges by introducing the chromophore 4,8-bis(n-octyloxy)-benzo[1,2-b:4,5-b′]dithiophene (BDT) into ZHG3 conversely decreases the PCE to 4.6%. Improving the coplanarity by replacing cyclobenzene with thiophene in ZHG4 after introducing BDT further decreases the PCE of ZHG4 to 4.3%. Theoretical calculations indicate that the LUMOs of ZHG3 and ZHG4 were mainly delocalized over benzothiadiazole which is far from the anchoring groups. Cyclic voltammetry experiments indicate that the LUMO energy levels of ZHG3 and ZHG4 are lower than those of ZHG1 and ZHG2. Both of these results affect the ability to inject electrons into the TiO2 conduction band. X-ray photoelectron spectroscopy (XPS) analysis shows that the mean thickness of the dye coverage for ZHG1, ZHG2, ZHG3 and ZHG4 is 16 Å, 18 Å, 27 Å and 24 Å, respectively. So the tilt angle of the dye backbone anchored on the TiO2 film is in the order of ZHG1 > ZHG2 > ZHG4 > ZHG3, which is consistent with the dye coverage of the outermost TiO2 surfaces. This result indicates that the intermolecular π–π aggregation in ZHG3 and ZHG4 with overlong π-bridges is more serious compared with that in ZHG1 and ZHG2. Perhaps the above two factors are the reason that the PCEs of ZHG3 and ZHG4 are lower than those of ZHG1 and ZHG2. So it is very important to find a balance point between the electron injection ability, intermolecular π–π aggregation and the expansion of the light absorption range.

A new copper-based coordination compound Cu2(2,2′-bipy)2(pfbz)4 (1) (where 2,2′-bipy = 2,2′-bipyridine; pfbz = pentafluorobenzoate), was hydrothermally synthesized and structurally characterized. Compound 1 having a binuclear structure consists of two copper cations and two oxygen atoms alternately in a plane square arrangement. In the presence of very small amounts of H2O2, the catalytic properties of compound 1 for the degradation of methyl orange (MO) are excellent in the absence of UV–visible radiation. Moreover, compound 1 presents suitable properties for degradation of Congo red (CR). Our results indicated that the five-coordinated copper compound, 1, will be a promising candidate for efficient degradation of organic dyes.

The herein obtained multifunctional compound is a promising fluorescent material that can give tunable fluorescence emissions by changing the solvent molecules. The fluorescence sensing behaviors are different for non-protonic and protonic solvents. To date, such a large response range of emission positions for fluorescent MOFs has not been reported before.

Two luminescent Zn(II) metal–organic frameworks were prepared from a π-conjugated thiophene-containing carboxylic acid ligand. These two MOFs show strong luminescene and their luminescence could be quenched by a series of nitroaromatic explosives. Importantly, they exhibit very highly sensitive and selective detection of picric acid compared to other nitroaromatic explosives.

Two supramolecular isomers, {[Co(L)(OBA)]·H2O}n (1), {[Co5O2(L)2(OBA)3]·7DMF}n (2), have been synthesized by one-pot reactions. Compound 1 has a homochiral architecture with low connectivity, and compound 2 is an achiral 3D framework with high 12-connectivity. It is unprecedent to get homochiral and achiral supramolecular isomers by one-pot synthesis.

Three supramolecular isomers, {[Cd2(TPOM)(hfipbb)2]·x/y/zsolvent}n (1–3), have been synthesized and characterized by one-pot reaction. Even though the compositions of 1–3 are the same, they generate different structures. Reactions over various time periods were found to influence the formation of supramolecular isomers, and there is little influence on this system under other conditions.

Three new metal–organic frameworks (MOFs) are designed by the assembly of flexible V-shaped ligands and paddle-wheel second building units (SBUs). The topology, interpenetration numbers and porosity of frameworks have been well controlled by a solvent system.

The self-assembly reaction of the preformed clusters with two extended linear and trigonal rigid ligands as organic linkers afforded two 2D and 3D Mo(W)/Cu/S-based cluster polymers. They show unprecedented structure types in Mo(W)/S/Cu chemistry and exhibit strong third-order nonlinear optical properties.

Dye-sensitized solar cells (DSSCs) have been considered as very promising third generation solar cells. Porphyrins are promising candidates as highly efficient sensitizers for DSSCs because of their superior light-harvesting ability in the visible region and their mimicking of photosynthesis. This paper focuses on the structure modification of porphyrin dyes for efficient DSSCs, which was based on a rational design using density functional theory (DFT) before the experiment. We synthesized and fully characterized four porphyrin dyes, named ZLD13, ZLD14, ZLD15 and ZLD16. On one hand, we used 5-ethynylthiophene-2-carboxylic acid to replace 4-ethynylbenzoic acid as the electron-withdrawing anchoring group for the first time. Property studies indicate that the aggregation of porphyrin molecules can be sufficiently suppressed via this modification. On the other hand, 4,4′-di(2-thienyl)triphenylamine moiety, which has been proved to be a electron donor group for triarylamine dyes in our previous reports, was introduced to porphyrin dyes, and energy conversion efficiencies (η) were improved by 76% (ZLD15 vs. ZLD13). After the two modifications, the energy conversion efficiency (η) of ZLD16 is comparable with an N719-based reference cell under the same conditions. Enhancement of photovoltaic performances from ZLD13 to ZLD16 is partly due to the decreased dark current and charge recombination rate.

A series of novel panchromatic D–D–π–A porphyrin dyes have been synthesized and applied to dye-sensitized solar cells. Three porphyrin dyes named JP1, JP2 and JP3, and their photophysical and electrochemical properties and photovoltaic performance were investigated and compared with reference dye YD2-O-C8. 2-Hexylthiophene chromophores were introduced to the donor groups, which extended the π-conjugation system effectively, then broadened the range of spectral response and improved the charge separation between the donor and acceptor moieties in the excited state. Moreover, this paper used thiophene-2-carboxylic acid instead of the traditional benzoic acid as an anchor group, which can make the molecules arrange to tilted orientation when adsorbed on the TiO2 surface, and this may effectively suppress the dye aggregation and prevent charge recombination. These dyes were clearly red-shifted when compared with dye YD2-O-C8. Especially for dye JP3, its maximum absorption peak was red shifted 20 nm with respect to dye YD2-O-C8 from 645 to 665 nm, and the molar extinction coefficient (6.2 × 104 M−1 cm−1) of JP3 is double that of YD2-O-C8 (3.1 × 104 M−1 cm−1) at the Q band. Dye JP3 extended the spectral response to 750 nm. The density functional theory (DFT) calculations indicated that the electronic density of the HOMO was increased by the additional thiophene units in these dyes when compared with YD2-O-C8, and this will improve the conjugation and electron donating ability. The power conversion efficiencies of JP1, JP2 and JP3 are 5.09%, 5.62% and 6.40% respectively under AM 1.5G irradiation, which are 74.5%, 82.3% and 93.7% of the YD2-O-C8 based-device (6.83%) under the same conditions.

We developed a novel efficient tridentate anchoring group which can anchor dyes onto the TiO2 surface via synchronously choosing Lewis acid sites and Brønsted acid sites of TiO2. For the purpose of comparing the traditional carboxylate anchoring group to picolinic acid, two new D–π–A porphyrin dyes (JA1 and JA2) differing only in anchoring groups have been synthesized and applied in dye-sensitized solar cells. Picolinic acid as an anchoring group in the dye JA2 not only extended the scope of the spectral response, but also improved the charge transport properties and enhanced the electron injection efficiency. The PCE of the JA1 based-device (carboxylate as the anchoring group) was 5.76%. The PCE of the JA2 based-device was 7.20%, which increased by 25% compared with JA1. The dye TTR2 was used as a cosensitizer; it would not just make up for the poor absorption of porphyrin dyes in the 470–550 nm range, but also would suppress the main dye aggregation and reduce the charge recombination rate. We found that the picolinic acid anchor was more suitable for the cosensitization system than the carboxylate anchor, for there was almost no competitive adsorption between JA2 and TTR2. The JA2 + TTR2 based-device showed the highest PCE of 8.98% under AM 1.5 G irradiation.

We prepared three new push–pull dyes JA3, JA4 and JA0 through structure optimization, and applied them in DSSCs. Judicious molecular structure optimization of dyes can significantly improve the performance of DSSCs. Spirobifluorene as a building block was introduced onto the phenothiazine donor groups. Compared to JA1, the steric effect of the spirobifluorene building block can effectively reduce charge recombination by preventing the I3− of the electrolyte penetrating into the TiO2 surface, thus the Voc of JA3 increased from 701 mV to 800 mV. In order to further improve the light-harvesting ability of the DSSC, we introduced a benzothiadiazole unit (BTD) and prepared D–A–π–A dye JA4. As expected, the Jsc of JA4 increased from 12.32 to 14.43 mA cm−2 compared to that of JA3, and the device reached the highest PCE of 7.0%. Moreover, since extending the π-conjugated system is known to decrease the Voc of DSSC, the porphyrin unit was removed and dye JA0 was synthesized. Notably, the DSSC based on JA0 reached a very high Voc of 840 mV and a high PCE of 6.69%: to our knowledge, this is the highest Voc for DSSCs based on phenothiazine dyes with I−/I3− electrolyte.

The self-assembly of 3,5-pyrazoledicarboxylic acid (H3pdc) and metal salts under hydrothermal conditions leads to the formation of a series of novel NaI–CuII–LnIII heterometallic coordination polymers, {[Na(H2O)4]2[Cu(pdc)2Ln(H2O)5]2·3H2O}n [Ln = La (1); Sm (2); Pr (3); Nd (4) and pdc3− = 3,5-pyrazoledicarboxylate]. X-Ray structure analyses show that these complexes all exhibit pairs of infinite, unexpected, cationic and anionic chains. It is the first successful attempt to construct unprecedented NaI–CuII–LnIII heterometallic coordination polymers with both infinite cationic and anionic chains. These four complexes show homologous thermal stabilities. The different magnetic properties of 1–3 are also been reported in this paper.

Three new isomorphic coordination polymers of Co2+, Zn2+ ions with flexible multicarboxylic acid ligand of the cis,cis,cis-1,2,3,4-cyclopentanetetracarboxylic acid (H4L), [Co4L2(H2O)8]·3H2O (1), [Zn4L2(H2O)8]·3H2O (2) and [Co0.8Zn3.2L2(H2O)8]·3H2O (3), have been synthesized under hydrothermal conditions and by means of controlling the pH of the reaction mixtures (with an initial pH of 6.0 for 1, 4.0 for 2, and 5.0 for 3, respectively). In the crystal of 1, two crystallographically different Co2+ ions (Co1 and Co2) form a negatively-charged coordination polymeric chain, which contains a centrosymmetric, linear, trinuclear Co2+ cluster (Co3L2) subunit; another crystallographically independent Co2+ ion (Co3) coordinated to six water molecules acts as a counter ions to link the neighboring coordination polymeric chains via intermolecular H-bond interactions. The Co2+ ions in 1 were completely and partially replaced by Zn2+ ions to give 2 and 3, respectively. Complex 3 shows a novel molecular alloy nature, due to the random distributions of the Co2+ and Zn2+ ions. Three isomorphic complexes exhibit distinct thermal decomposition mechanisms. The deprotonated cis,cis,cis-1,2,3,4-cyclopentanetetracarboxylic acid ligands decompose at 420–750 °C to give the residue CoO in 1, ZnO + C in 2 and CoO + ZnO in 3. Complex 1 shows a complicated magnetic behavior with co-existence of antiferromagnetic exchange interactions between neighboring Co2+ ions as well as strong spin–orbital coupling interactions for each Co2+ ion; complex 3 exhibits a magnetically isolated high-spin Co2+ ion behavior with strong spin–orbital coupling interactions.

The solvothermal reactions of 1,1′-oxybis[3,5-di-4-pyridine]-benzene (L) and transition metal cations (Co and Ni) afford five novel coordination polymers in the presence of flexible bridging ligands (4,4′-H2nba = 4,4′-dicarboxydiphenylamine, H2cam = D-camphoric acid, 4,4′-H2sdb = 4,4′-sulfonyldibenzoic acid, H2chdc = 1,4-trans-cyclohexanedicarboxylic acid), namely {[Co2L2(OH)2(nba)]·2DMF}n (1), {[CoL(cam)(H2O)]}n (2), {[Co3(L)(4,4′-sdb)3(H2O)]·1.5CH3CN·4H2O}n (3), {[Ni3(L)(4,4′-sdb)3(H2O)]·1.5CH3CN·4H2O}n (4), and {[Ni2L2(chdc)2(H2O)2]·(H2O)3}n (5) (DMF = N,N-dimethylformamide). Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectroscopy, and powder X-ray diffraction. Complex 1 reveals a 2-fold interpenetrating three-dimensional (3D) framework with the Schläfli symbol {4·8·104}{4·8·10} topology. Compound 2 crystallizes in the achiral space group with the D-camphorate ligand racemized. Compounds 3 and 4 reveal similar structure with the {3·44·6}{32·48·59·69} topology based on a linear trinuclear building block M3(OOCR)6 (M = Co(II) or Ni(II)). Compound 5 is a wavy sheet, where both carboxylate and L ligands act as bidentate ligands. Moreover, UV-Visible absorption spectra of complexes 1–3, 5 and the magnetic properties of 3 have been investigated.

Six new cobalt(II) metal–organic frameworks, {[Co1.5(TTPA)(BTC)(H2O)]2·13H2O}n (1), [Co(TTPA)(PA)]n (2), {[Co(TTPA)(BDA)0.5(NO3)]·3H2O}n (3), {[Co2(TTPA)3(OBA)2(H2O)3]·2CH3CN·4H2O}n (4), {[Co(TTPA)(AIP)(H2O)]·2H2O}n (5), and {[Co(TTPA)(MIP)(H2O)]·2H2O}n (6), have been prepared by the self-assembly of a tris(4-(1H-1,2,4-triazol-1-yl)phenyl)amine (TTPA) ligand with different aromatic carboxylate auxiliary ligands (H3BTC = 1,3,5-benzenetricarboxylic acid, H2PA = phthalic acid, H2BDA = (1,1′-biphenyl)-4,4′-dicarboxylic acid, H2OBA = 4,4′-oxydibenzoic acid, H2AIP = 5-aminoisophthalic acid, H2MIP = 5-methylisophthalic acid) and cobalt salts. Their structures have been characterized by infrared spectroscopy, elemental analysis, single crystal X-ray analysis, and powder X-ray diffraction. Complex 1 is an unusual 4-nodal (3,3,4,8)-connected three-dimensional (3D) new topological net with the point symbol of (4·6·8)4(44·67·815·102)(62·84). Complex 2 has a 2-fold interpenetrating 3D dia framework. Complex 3 displays a rare binodal (3,4)-connected 4-fold interpenetrating 3D architecture with a fsc-3,4-C2/c topology with the point symbol of (4·6·8)(4·62·83). Complex 4 shows two distinct two-dimensional (2D) layers with hcb topologies, which are further packed into a 3D structure by O–H⋯O hydrogen bonding interactions. Both complexes 5 and 6 feature similar 2D sheets with sql topologies, which can be further packed into a 3D structure by O–H⋯O hydrogen bonding interactions. Moreover, the thermal stability and UV-visible spectra of these complexes are also discussed in detail. Meanwhile, the variable-temperature magnetic susceptibility measurement of complex 1 reveals antiferromagnetic interactions between Co(II) ions.

Five new metal complexes, {[Ni(DIDP)(m-bdc)(H2O)]·5H2O}n (1), {[Zn(DIDP)(hfipbb)]·2DMA}n (2), {[Zn(DIDP)(4,4′-sdb)]·H2O}n (3), {[Co(DIDP)(p-bdc)]}n (4), and {[Co2(DIDP)(hfipbb)2]·H2O}n (5), have been synthesized by reactions of the corresponding metal ions with a V-shaped ligand 2,8-di(1H-imidazol-1-yl)dibenzothiophene (DIDP) and different aromatic dicarboxylic acids, namely isophthalic acid (m-H2bdc), terephthalic acid (p-H2bdc), 4,4′-(hexafluoroisopropylidene)bis(benzoic acid) (H2hfipbb), and 4,4′-sulfonyldicarboxylic acid (4,4′-H2sdb), respectively. The structures of the complexes were determined by X-ray single-crystal diffraction. Complex 1 is a 1D chain structure containing a one-dimensional channel along the a direction and is further extended via O–H⋯S hydrogen bonds and C–H⋯π stacking interactions into a 3D framework. Complex 2 exhibits a quasi 2D + 2D → 2D with parallel polycatenation of 2D (4, 4) nets. Complex 3 displays an unusual 2D + 2D → 3D parallel polycatenated framework based on a 2D 63-hcb network. Complex 4 shows a 2D 4-connected {44·62}-sql network containing a one-dimensional channel along the b direction. The adjacent 2D networks are further extended via C–H⋯O hydrogen bonds into a 3D supramolecular framework. Complex 5 features a 2-fold interpenetrating 3D framework with a 6-connected {412·63} pcu topology. Furthermore, the thermal stability for 1–5 and luminescence properties of 2 and 3 have been studied. Moreover, the solid-state UV-visible spectroscopy experiments show that complexes 1–5 are all optical semiconductors with band gaps of 3.06, 3.18, 3.23, 2.98, and 3.17 eV, respectively.

Five new cobalt(II) coordination architectures, {[Co(L)2(H2O)2]·2H2O·2NO3}n (1), {[Co(L)(ppda)]·2H2O}n (2), {[Co2(L)(ppda)2]2·H2O}n (3), {[Co(L)(nba)]·5H2O}n (4), and {[Co(L)(oba)]2·3H2O}n (5), have been constructed from the rigid ligand L [L = 2,8-di(1H-imidazol-1-yl)dibenzofuran] and different flexible carboxylic acid ligands [H2ppda = 4,4′-(perfluoropropane-2,2-diyl)dibenzoic acid, H2nba = 4,4′-azanediyldibenzoic acid, and H2oba = 4,4′-oxydibenzoic acid]. Depending on the nature of the solvent systems, these five different coordination polymers were synthesized and characterized by single-crystal X-ray diffraction, IR, PXRD and elemental analysis. Compounds 1, 2 and 3 were obtained by a one-pot method, and then we utilized the solvent-induced effect to obtain almost pure crystals of 1–3, respectively. Compound 1 is an infinite 1D chain which is formed by L ligands and Co atoms. Compound 3 contains a [Co2(CO2)4] secondary building unit (SBU), and can be topologically represented as a 6-connected 2-fold interpenetrating pcu net with the point symbol of {412·63}. Compound 4 can be characterized as a 4-connected sql tetragonal planar network with the point symbol of {44·62}. In compounds 2 and 5, there is a 1D chain which is formed by flexible carboxylic acid ligands and Co atoms; then the 1D chain is linked by L ligands in the tilting direction, leading to the formation of a 2D layer. Furthermore, UV-vis, TGA and magnetic properties have been investigated in detail.

Chiral coordination polymers have attracted much attention due to their special properties and significant applications. In this work, we synthesized two non-centrosymmetric ligands, N,N-bis(4-(1H-imidazol-1-yl)phenyl)-4-(pyridin-4-yl)aniline (DIMPPA) and N-(4-(1H-imidazol-1-yl)phenyl)-4-(pyridin-4-yl)-N-(4-(pyridin-4-yl)phenyl)aniline (MIDPPA), via structural modification of two reported centrosymmetric ligands; after that achiral → chiral induction occurred in the construction of three coordination polymers namely {[Cd(DIMPPA)(5-OH-bdc)](H2O)}n (1), {[Co(DIMPPA)(5-OH-bdc)](H2O)}n (2) and {[Cd2(MIDPPA)2(D-ca)2(H2O)2](H2O)5}n (3), when replacing the reported centrosymmetric ligands with non-centrosymmetric ligands (5-OH-H2bdc = 5-hydroxyisophthalic acid, D-H2ca = D-camphoric acid). Isostructural complexes 1 and 2 exhibit chiral 2D → 3D frameworks with the coexistence of polyrotaxane and parallel polycatenation features. Complex 3 shows two-fold interpenetrating 3D chiral architecture with cds-type topology. The luminescence emissions of both complexes 1 and 3 are mostly assignable to the internal π→π* electron transition in DIMPPA and MIDPPA, respectively. Complex 3 can satisfy the fundamental requirement of second-order nonlinear optical materials.

Three new Co-based MOFs with a nanosized tetradentate pyridine ligand, N,N,N′,N′-tetrakis(4-(4-pyridine)-phenyl) biphenyl-4,4′-diamine (TPPBDA) and carboxylate co-ligands, [Co(TPPBDA)(NO3)2]n·2H2O (1), [Co2(TPPBDA)(bpdc)2 (H2O)]n·2DMA (2) and [Co(TPPBDA)0.5(hfipbb)(H2O)]n·3.5H2O (3) (H2bpdc = biphenyldicarboxylic acid, H2hfipbb = 4,4′-(hexafluoroisopropylidene)bis-(benzoic acid), DMA = N,N-dimethylacetamide) have been synthesized under hydrothermal conditions. For complex 1, a large cavity causes a 4-fold interpenetration of the network, which can be classified as a type IIIa mode of interpenetration. Complex 2 reveals a non-interpenetrating three-dimensional (3D) framework based on the [Co2(μ2-H2O)(CO2)2] unit. Complex 3 is also a 2-fold interpenetrating 3D net based on the [Co2(CO2)2] cluster. These mononuclear or dinuclear cluster units are interconnected by TPPBDA and carboxylate co-ligands, resulting in interesting structural diversities and various degrees of interpenetration.

A series of new metal–organic frameworks (MOFs) based on a triangular tri(4-pyridylphenyl)amine (TPPA) ligand that possess novel structures and features, namely [Co2(TPPA)2(1,3-bdc)2(H2O)]n (1); [Zn(TPPA)(1,3-bdc)]n (2); [Zn6(TPPA)2(betc)(Hbetc)2(H2betc)(H2O)6·7H2O·2DMA]n (3) and [Cu(TPPA)(NO3)2(H2O)]·2H2O]n (4) (1,3-H2bdc = 1,3-benzenedicarboxylic acid, betc = 1,2,4,5-benzenetetracarboxylic dianhydride), have been synthesized under solvothermal conditions. In our work different MOFs were synthesized from different metal ions and in different solvents, leading to a variety of coordination modes and structures. In addition, the photochemical properties of compounds 1–4 and the ligands in the solid state were studied.

Four different Co(II) coordination polymers have been built by two flexible ligands 4,4′-dicarboxydiphenyl sulfone (4,4′-sdb) and 1,4-bis((1H-imidazol-1-yl)methyl) benzene (BMB) in a one-pot solvothermal reaction. The structures of 1 and 2 are new, and 3 and 4 have been reported. The crystal structures of 1–3 were obtained, namely [Co(4,4′-sdb)(BMB)]n (1), {[Co2(4,4′-sdb)2(BMB)]·2H2O}n (2), and [Co3(4,4′-sdb)2(DMF)(H2O)3]n (3), but 4 was confirmed by PXRD. Both 1 and 2 are 2D layered structures with sql topology and their point symbol is {44·62}. These complexes have been characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction measurements. By changing the synthesis conditions, four different Co(II) coordination polymers can be obtained respectively.

The first luminescent metal–organic framework (MOF) with [Zn6(μ6–O)] cluster has been synthesized and realized for reversible sensing of small molecules.

A highly connected 3D metal–organic framework with tfz-d topology based on Zn6O2 clusters and flexible carboxylate ligands has been synthesized. The obtained Zn-MOF shows solvatochromic behavior for fluorescence sensing of small molecules, gas adsorption properties and exceptional chemical stability and might have applications for separation and detection purposes.

A unique supramolecular helix assisted by solvent molecules (water and DMF) is obtained from an achiral flexible V-shaped ligand, and spontaneous symmetry breaking occurs in crystallization. Notably, the compound displays strong second-harmonic generation (SHG) response.

Three different Co-MOFs, [Co3(L)2(DPDP)]n (1), [Co(HL)(DPDP)]n (2) and {[Co(HL)(1/2DPDP)3(H2O)]·H2O}n (3) (H3L = 4,4′,4′′-(nitrilotris(methylene))tribenzoic acid, DPDP = 4,4′-(2,5-dibutoxy-1,4-phenylene)dipyridine) have been co-crystallized in a one-pot reaction. Based on the significant differences between the three structures, we adopt solvents to ultimately regulate acquisition of pure crystals of the three compounds.

A rare chiral 3D cluster–organic framework {[Zn17O5(NTB)6(NDB)3]·41H2O}n (1) (H3NTB = 4,4′,4′′-nitrilotrisbenzoic acid and H2NDB = 4,4′-nitrilodibenzoic acid) was prepared and structurally characterized. Complex 1 contains two types of [Zn4(μ4-O)(COO)6] and unreported [Zn9(μ3-O)3(COO)12] SBUs, which link bi- and tri-carboxylic acids and extend to an unprecedented (3,6,12)-connected framework. In addition, electronic structure calculations were performed to scrutinize the features of embedded clusters.

Three new coordination polymers have been synthesized based on three linear pyridine ligands with different side chains and one flexible V-shaped dicarboxylate co-ligand: {[Co(L1)0.5(sdb)]}n (1), {[Co(L2)0.5(sdb)]·1.5H2O}n (2) and {[Co(L3)0.5(sdb)]·2DMF}n (3) (L1 = E,E-2,5-dioctyloxy-1,4-bis-[2-pyridin-vinyl]-benzene; L2 = E,E-2,5-dibutoxy-1,4-bis-[2-pyridin-vinyl]-benzene; L3 = E,E-2,5-dimethoxy-1,4-bis-[2-pyridin-vinyl]-benzene; H2sdb = 4,4′-sulfonyldibenzoic acid). Complexes 1–3 are 4-connected sql nets with a point symbol of {44·62}. The interpenetration forms and porosity of frameworks have been well controlled by side chain prolongation. A larger steric hindrance for the pendant –OnOct and –OnBut groups leads to a larger repulsive force between the layers and effective construction of inclined polycatenations. A smaller steric hindrance for the pendant –Me group leads to the formation of a parallel stacked network. Therefore, compounds 1 and 2 feature 3D structures with inclined polycatenation (2D + 2D → 3D); compound 3 exhibits a non-interpenetrated 2D + 2D → 2D parallel stacked network. These complexes have been characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction measurements. In addition, the gas adsorption properties of the compounds have also been explored.

A pair of new enantiomeric Zn(II) complexes with 5-fold interpenetrating diamondoid frameworks have been synthesized using two achiral tritopic and V-shaped ligands through spontaneous resolution, which crystallize in orthorhombic crystal systems with chiral P212121 space groups, showing a strong second harmonic generation response. In the presence of enantiopure propane-1,2-diol as a chiral inducing agent, they are driven to controllable homochiral crystallization of the desired enantiomorph, confirmed by single crystal X-ray diffraction and circular dichroism spectroscopy.

Four Cd(II)-based compounds (1–4) were synthesized from solvothermal reactions involving the in situ aldimine condensation of an o-diamino-functionalized precursor 3,6-di(4H-imidazol-4-yl)benzene-1,2-diamine (L), Cd(NO3)2·4H2O and aldehyde. Two modes of cycloaddition ([4 + 1] cycloaddition and [4 + 2] cycloaddition) occurred during condensation, causing the in situ generation of two benzimidazole derivative ligands (L1 and L3) and a quinoxaline derivative ligand (L2). Furthermore, the chemical selectivity of the condensation was studied, where the condensation of o-diamino and the aldehyde is more stable and easy to operate. This strategy enriches the synthesis method of MOFs. Additionally, compound 2 containing uncoordinated quinoxaline N atoms showed excellent luminescent sensitivity for Fe3+ detection.

Four coordination polymers with different metal ions have been synthesized based on a rigid linear pyridine and a flexible V-shaped dicarboxylate ligand (L = 4,4′-(2,5-dimethoxy-1,4-phenylene)dipyridine; H2OBA = 4,4′-oxydibenzoic acid): {[Co(L)(OBA)]·2H2O}n (1), [Zn(L)(OBA)·2H2O]n (2), {[Ni(L)(OBA)]·DMF·H2O}n (3), [Cd(L)(OBA)]·DMF·H2O}n (4). The reaction conditions are similar except for the metal ions for complexes 1–4. Complexes 1 and 2 present a 3D unprecedented hxg-d-4-Cccm net, but 3 and 4 are 4-connected sql nets with a point symbol {44·62}. These complexes were characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction measurements. The UV–visible spectra, fluorescence, and gas adsorption properties of the compounds were also explored.

Dye-sensitized solar cells (DSSCs) are currently under intense academic and industrial investigations, because of their environmentally-friendly, efficient, and low-cost features. The photosensitizer plays a key role in determining DSSCs' performance. The 4,4′-di(2-thienyl)triphenylamine moiety, included in dye TTC102, has been demonstrated before as a novel and efficient electron donor fragment. In this paper, the oversimple π-conjugated bridge of TTC102 was replaced by a 9-ethyl-3,6-di(2-thiophenyl)carbazole moiety. Two new D-D-π-A sensitizers, named TTC104 and TTC105, were synthesized and fully characterized. After anchoring on TiO2 nanoparticle film, the absorption band of TTC104 is broader by 30 nm than that of TTC102. Under AM 1.5G irradiation, the energy conversion efficiency (η) of a DSSC based on TTC104 reaches 6.36%, which is 21.6% higher than that of TTC102 (5.24%). The results above demonstrate that the photovoltaic performance can be improved after introducing the 9-ethyl-3,6-di(2-thiophenyl)carbazole moiety to TTC102 when employed in DSSCs. Dye TTC105, containing a pyridyl group as the electron acceptor, showed only 1.88% conversion efficiency (η) when used in DSSCs. The huge different performances of TTC104 and TTC105 are proved to be partly due to the smaller dye loading amount, higher dark current and charge recombination rate of TTC105.

Two new D–π–A zinc porphyrin dyes with thiophene and furan π-bridges have been synthesized and employed in dye-sensitized solar cells (DSSCs). Here, the triphenylamine (TPA) moiety was used as the electron donor, and the hexylthiophene chromophores were introduced onto the donor groups, which effectively extended the π-conjugation system. Although the two dyes had similar molecular structures, there was a significant difference between their optical and photoelectric properties. The EIS analysis suggested that the dye with the thiophene π-bridge had a lower charge recombination rate compared to the dye with the furan π-bridge. Based on their light-harvesting abilities, the power conversion efficiency (PCE) of dye JP-S was higher than that of dye JP-O. The JP-S-based DSSC showed a PCE of 5.84%, whereas the PCE of the JP-O-based DSSC was 4.68%. Moreover, using the dye TTR1 as a co-sensitizer made up for the poor absorption of porphyrin dyes in the 480–600 nm range and reduced the charge recombination. The JP-S + TTR1-based DSSCs showed a higher PCE of 6.71%, and the Jsc and Voc values of the device were both increased using this strategy.