An anionic metal–organic framework (MOF) {(NH2Me2)[Zn3(μ3-OH)(tpt)(TZB)3](DMF)12}n (1, tpt = 2,4,6-tri(4-pyridyl)-1,3,5-triazine, H2TZB = 4-(1H-tetrazol-5-yl)benzoic acid and DMF = N,N-dimethylformamide), with both nanosized cages and partitions, has been solvothermally synthesized, which can serve as a crystalline vessel to encapsulate the fluorescent dye rhodamine 6G (Rh6G) via a “bottle around ship” approach. As a result, the obtained dye@MOF composite system features a blue emission of the ligand at 373 nm and a red emission of Rh6G at 570 nm when dispersed in solution, which could be used for decoding the trace amount of 2,4,6-trinitrophenol (TNP) by referring the peak-height ratio of each emission, even in coexistence with other potentially competitive nitroaromatic analytes. Furthermore, the observed fluorescence responses of the composite toward TNP are highly stable and reversible after recycling experiments. To the best of our knowledge, this is the first example of an MOF-implicated self-calibrated sensor for TNP detection.Keywords: composite; dual-emitting; metal−organic framework; self-calibrated sensor; TNP detection;

The self-assembly of a bifunctional organic ligand with a formate-bridged rod-shaped secondary building unit leads to a new microporous metal–organic framework (MOF). This MOF shows a moderately high C2H2 storage capacity (145 cm3/g) and an excellent adsorption selectivity for C2H2/CO2 (11) at room temperature. Furthermore, its discriminatory sorption behavior toward C2H2 and CO2 was probed by computational analysis in detail.

Metal–organic frameworks (MOFs), as a class of adjustable porous crystalline materials, have received considerable attention in recent years. In this study, starting from an unstable MIL-88 type Co(II)-MOF as the prototype structure, two isoreticular stabilized MOFs with similar structural features but different water/thermal stabilities and acetylene sorption behaviors were prepared, which can be modulated by incorporating different functional brackets in the pores. MOF 1 equipped with open metal sites (OMSs) decomposed quickly in water solution, while the free N-donor functionalized MOF 2 could be stable in water with improved thermostability. The gas sorption study reveals that activated material 2 has a significantly enhanced acetylene uptake capacity with a lower Qst value than those of activated 1, showing a 79% increase (242 vs. 135 cm3 g−1) at 273 K and 91% increase (165 vs. 86 cm3 g−1) at 298 K. The acetylene uptake capacity of activated material 2 is extraordinarily high among MOFs without OMSs, and is even comparable to some famous MOFs with much stronger C2H2 binding ability which however require considerably higher energy for regeneration. The experimental results were further confirmed by the molecular mechanics (MM) calculations, grand canonical Monte Carlo (GCMC) simulations and density functional theory (DFT) studies.

•A core–shell nanostructured Fe-MOF@mFe3O4@mC-based aptasensor was constructed.•High sensitivity, selectivity and low detection limit of the developed aptasensor.•Ultra-sensitively detecting trace heavy metal ions in river water and human serum.A new core–shell nanostructured composite composed of Fe(III)-based metal–organic framework (Fe-MOF) and mesoporous Fe3O4@C nanocapsules (denoted as Fe-MOF@mFe3O4@mC) was synthesized and developed as a platform for determining trace heavy metal ions in aqueous solution. Herein, the mFe3O4@mC nanocapsules were prepared by calcining the hollow Fe3O4@C that was obtained using the SiO2 nanoparticles as the template, followed by composing the Fe-MOF. The Fe-MOF@mFe3O4@mC nanocomposite demonstrated excellent electrochemical activity, water stability and high specific surface area, consequently resulting in the strong biobinding with heavy-metal-ion-targeted aptamer strands. Furthermore, by combining the conformational transition interaction, which is caused by the formation of the G-quadruplex between a single-stranded aptamer and high adsorbed amounts of heavy metal ions, the developed aptasensor exhibited a good linear relationship with the logarithm of heavy metal ion (Pb2+ and As3+) concentration over the broad range from 0.01 to 10.0 nM. The detection limits were estimated to be 2.27 and 6.73 pM toward detecting Pb2+ and As3+, respectively. The proposed aptasensor showed good regenerability, excellent selectivity, and acceptable reproducibility, suggesting promising applications in environment monitoring and biomedical fields.

The authors describe an electrochemical immunoassay for the β-adrenergic agonist ractopamine (RAC). It is based on the use of chitosan-stabilized gold nanoparticles (chit-AuNPs). Antibodies against RAC (anti-RAC) readily adsorb on the surface of the chit-AuNPs due to their high bio-affinity. The amount of chitosan used to synthesize chit-AuNPs does not affect the size and distribution of the NPs but amplifies the electrochemical signal of the electrode. The assay has a detection limit as low as 2.3 pg∙mL−1 (equivalent to a 6.7 fM concentration), with a response that is linear in the 0.01 to 5 ng∙mL−1 RAC concentration range. The assay is selective, acceptably reproducible, stable, and well applicable to the detection of RAC.

AbstractAs the first example of a photocatalytic system for splitting water without additional cocatalysts and photosensitizers, the comparatively cost-effective Cu2I2-based MOF, Cu-I-bpy (bpy=4,4′-bipyridine) exhibited highly efficient photocatalytic hydrogen production (7.09 mmol g−1 h−1). Density functional theory (DFT) calculations established the electronic structures of Cu-I-bpy with a narrow band gap of 2.05 eV, indicating its semiconductive behavior, which is consistent with the experimental value of 2.00 eV. The proposed mechanism demonstrates that Cu2I2 clusters of Cu-I-bpy serve as photoelectron generators to accelerate the copper(I) hydride interaction, providing redox reaction sites for hydrogen evolution. The highly stable cocatalyst-free and self-sensitized Cu-I-bpy provides new insights into the future design of cost-effective d10-based MOFs for highly efficient and long-term solar fuels production.

A flexible bidentate polyaromatic acid ligand 4,4′-oxybis(benzoic acid) (H2oba) was used for the construction of a novel luminescent Tb(III)-based metal–organic framework (MOF), namely {(Me2NH2)[Tb(OBA)2]·(Hatz)·(H2O)1.5}n, with 3-amino-1,2,4-triazole (Hatz) as the template reagent. In the structure of the Tb-MOF, there co-exist single-stranded and double-stranded helical chains along the c axis, and the overall network shows a three-fold interpenetrated qtz net. This MOF is capable of selectively sensing Fe3+ and Al3+ ions in water via quenching the luminescence and tuning the emission ratio between the ligand-based and metal-based luminescence, respectively. More importantly, this MOF can realize fast detection for p-xylene (PX) vapor with a response time of less than 10 s and 40% fluorescence enhancement, while nitrobenzene (NB) vapor could lead to a quenching effect in 10 min with a 75% quenching efficiency. Remarkably, this is the first example of a multi-responsive luminescent Tb-MOF sensor for Fe3+ and Al3+ ions and VOC vapor detection. In connection to these, the probable sensing mechanisms were also discussed in this paper.

A terbium(III) lanthanide–organic framework (534-MOF-Tb) with a green-emission signal was successfully obtained by the solvothermal reaction of Tb3+ ions with the organic ligand H3TBOT (2,4,6-tris[1-(3-carboxylphenoxy)ylmethyl]mesitylene). 534-MOF-Tb contains microporous quadrangle channels with accessible Lewis-base sites and coordinated water molecules, which are feasible to anchor and recognise multifarious analytes. It can serve as a recyclable multi-responsive sensing material for detecting Fe3+, MnO4−, Cr2O72−, and p-nitrotoluene (4-NT). Significantly, this is the first reported MOF-based sensor for detecting explosive 4-NT. Moreover, the mechanism of the selective luminescence quenching response for Fe3+, MnO4−, Cr2O72− or 4-NT can be mainly explained in terms of the competition between the absorption of the light source energy and the electronic interaction between the analyte and the TBOT ligand.

A cage-based anionic Na(I)–organic framework with a unique Na9 cluster-based secondary building unit and a cage-in-cage structure was constructed. The selective separation of dyes with different charges and sizes was investigated. Furthermore, the Rh6G@MOF composite could be applied as a recyclable fluorescent sensor for detecting picric acid (PA) with high sensitivity and selectivity.

A series of nanocomposites comprised of iron oxide and mesoporous carbon (denoted as Fe3O4@mC) were derived from an Fe(II)-based metal–organic framework (525-MOF) by calcining at different temperatures. The advantages of chemical functionality, strong bioaffinity, and high stability of the Fe3O4@mC can be combined with the high specific surface area of 525-MOF leading to the formation of Fe3O4@mC nanocomposites as a scaffold for oxytetracycline (OTC) aptamer strands. The use of Fe3O4@mC nanocomposites reveals high OTC detection efficiency. The nanocomposite calcined at 900 °C (denoted as Fe3O4@mC900) is found to be the best candidate toward high-sensitivity and high-selectivity detection of OTC because of its excellent functionality, nanostructural properties, and high electrochemical performance. Accordingly, the Fe3O4@mC900-based electrochemical aptasensor displays high sensitivity with a low detection limit of 0.027 pg mL−1 within a broad linear range of OTC concentration from 0.005 to 1.0 ng mL−1. The aptasensor also exhibits high selectivity, reproducibility, stability, regenerability, and applicability in milk samples. All of these results indicate that the Fe3O4@mC nanocomposites that originated from 525-MOF can be applied in the fields of trace and fast antibiotic determination.

A unique channel-type metal–organic framework (MOF) built up from mixed square-planar Co4(μ2-OH)4(μ4-OH) and cuboidal Co4(μ3-OH)4 clusters with an isonicotinic acid ligand has been successfully fabricated that demonstrates the highest specific surface area and high H2 uptake capacities among all of the cobalt(II) isonicotinic acid frameworks reported so far.

To avoid the instability and inefficiency for anion-exchange resins and layered double-hydroxides materials, we present herein a flexible coordination network [Ag(L243)](NO3)(H2O)(CH3CN) (L243 = 3-(2-pyridyl)-4-(4-pyridyl)-5-(3-pyridyl)-1,2,4-triazole) with superefficient trapping capacity for permanganate, as a group-7 oxoanion model for radiotoxic pertechnetate pollutant. Furthermore, a high-throughput screening strategy has been developed based on concentration-gradient design principle to ascertain the process and mechanism for anion exchange. Significantly, a series of intermediates can be successfully isolated as the qualified crystals for single-crystal X-ray diffraction. The result evidently indicates that such a dynamic material will show remarkable breathing effect of the three-dimensional host framework upon anion exchange, which mostly facilitates the anion trapping process. This established methodology will provide a general strategy to discover the internal secrets of complicated solid-state reactions in crystals at the molecular level.Keywords: anion exchange; capture mechanism; crystal transformation; dynamic porous material; high-throughput screening;

A moisture-stable three-dimensional (3D) metal–organic framework (MOF), {(Me2NH2)[Zn2(bpydb)2(ATZ)](DMA)(NMF)2}n (1, where bpydb = 4,4′-(4,4′-bipyridine-2,6-diyl)dibenzoate, ATZ = deprotonated 5-aminotetrazole, DMA = N,N-dimethylacetamide, and NMF = N-methylformamide), with uncoordinated N-donor sites and charged framework skeleton was fabricated. This MOF exhibits interesting structural dynamic upon CO2 sorption at 195 K and high CO2/N2 (127) and CO2/CH4 (131) sorption selectivity at 298 K and 1 bar. Particularly, its CO2/CH4 selectivity is among the highest MOFs for selective CO2 separation. The results of Grand Canonical Monte Carlo (GCMC) simulation indicate that the polar framework contributes to the strong framework–CO2 binding at zero loading, and the tetrazole pillar contributes to the high CO2 uptake capacity at high loading. Furthermore, the solvent-responsive luminescent properties of 1 indicate that it could be utilized as a fluorescent sensor to detect trace amounts of nitrobenzene in both solvent and vapor systems.

Incorporating the in situ formed size-matching molecular building blocks (MBBs) into the open channels will remarkably improve the robustness and gas sorption performance of an evacuated metal–organic framework. As a result, such MBBs can transfer the open metal sites from the framework walls to the channel centers and separate the large channels into multiple smaller voids, leading to a molecular sieving effect and high-performance gas-separation of the modified material.

Two isomorphic 3-D complexes with the formulas [M3(TPTA) (OH)2(H2O)4]n (M = Ni for 1 and Co for 2; H4TPTA = [1,1′:4′,1″-terphenyl]-2′,3,3″,5′-tetracarboxylic acid) have been synthesized and magnetically characterized. Complexes 1 (NiII) and 2 (CoII) have the same 1-D rod-shaped inorganic SBUs but exhibit significantly different magnetic properties. Complex 2(CoII) is a 3-D arrangement of a 1-D CoII single-chain magnet (SCM), while complex 1(NiII) exhibits weak coupling.

Herein, we report the synthesis of a new mixed-linker Zn(II)-based metal–organic framework (MOF), {[Zn2(atz)2(bpydb)](DMA)8}n (1) (atz = deprotonated 3-amino-1,2,4-triazole, bpydb = deprotonated 4,4′-(4,4′-bipyridine-2,6-diyl) dibenzoic acid, DMA = N,N-dimethylacetamide), through symmetry modulation of a triazole ligand. The desymmetrized triazole linkers not only bond to the Zn(II) ions to result in a new helical Zn-triazolate chain building unit but also lead to the formation of a highly porous framework (N2 uptake: 617 cm3/g; BET surface area: 2393 m2/g) with 1D helical channels. The adsorption properties of desolved 1 were investigated by H2, C2H2, CO2, and CH4 sorption experiments, which showed that 1 exhibited high uptake capacity for H2 at 77 K and C2H2 around room temperature. More importantly, the high C2H2 uptake capacity but low binding energy makes this MOF a promising candidate for effective C2H2 capture from C2H2/CO2 and C2H2/CH4 mixed gases with low regenerative energy cost. In addition, 1 shows potential application for the luminescence sensing of small aromatic molecules picric acid (PA) and p-xylene (PX).

Two isomeric Zn(II)-based metal–organic frameworks, {[Zn(CPT)2](NMF)3}n (1) and {[Zn(CPT)2](DMF)0.75}n (2) (HCPT = 4-(4-carboxyphenyl)-1,2,4-triazole, NMF = N-methylformamide, DMF = N,N-dimethylformamide), with the same 4-fold interpenetrated dia topological network have been prepared under solvothermal conditions by employing a bifunctional triazolate–carboxylate organic linker, which show very similar voids but different pore shapes. Thermogravimetry, powder X-ray diffraction, molecular mechanics calculation, and gas sorption studies revealed their different framework stabilities and flexibilities, in which desolvated 1 exhibits temperature-dependent stepwise and hysteretic selective sorption of CO2 over N2 at 195 K, whereas desolvated 2 could adsorb neither CO2 nor N2. Furthermore, the luminescence properties of 1 and 2 were investigated.

Two pairs of alkaline earth metal-based MOFs have been synthesized by spontaneous self-assembly reactions of Mg(II) or Ca(II) and two tricarboxylate ligands, H3BTTB and H3TCM (H3BTTB = 4,4′,4′′-[benzene-1,3,5-triyl-tris(oxy)]tribenzoic acid; H3TCM = 4,4′,4′′-{[(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)]tris(oxy)}tribenzoic acid), in different solvent media. The Mg/BTTB assemblies, {[Mg3/2(BTTB)(H2O)(DMF)](DMF)}n (1) (DMF = N,N′-dimethylformamide) and {[Mg3/2(BTTB)(DMAc)2](DMAc)0.5}n (2) (DMAc = N,N′-dimethylacetamide), are prepared in DMF/H2O and DMAc/H2O media, respectively, and feature uniform kgd-type 2D bilayer structures but with different compactness. Meanwhile, two Ca/TCM assemblies, {[Ca5/2(TCM)2(DMF)2(H2O)](Me2NH2)(DMF)2(H2O)}n (3) and {[Ca3(TCM)2(DMAc)3(H2O)2](DMAc)5}n (4), have been achieved in DMF/H2O and DMAc/H2O mixed systems as well. However, compounds 3 and 4 have an enormous structural discrepancy, that is, compound 3 shows a complicated parallel 2D → 3D polycatenaned supramolecular architecture while 4 exhibits a 2-fold interpenetrating sit-type 3D framework. These various coordination patterns evidently illustrate the solvent regulation on the alkaline earth metal-based MOFs. The single-crystal-to-single-crystal structural transformation experiment reveals that the loose kgd-network compound 2 can be converted into the compact isoreticular compound 1 when immersed in DMF for 12 h. However, the reversed conversion cannot be realized. In addition, their thermal stability, gas adsorption, and solid-state fluorescence properties have also been investigated.

By virtue of unique planar [Co6(μ3-OH)4] cluster units, a new microporous isonicotinate-based framework with high thermal and framework stabilities was achieved. The guest-free framework demonstrates high capacity and selectivity for C2H2 relative to CO2 and CH4 at room temperature, which was further understood by GCMC simulation.

•A versatile Li(I)-based metal − organic framework•Exhibiting rare ant topological net and binuclear Li(I) SBUs•Selective luminescent detection and mechanismA new Li(I)-based metal–organic framework (MOF), namely {(Me2NH2)2[Li(NTB)](H2O)3(DMF)2}n (1, NTB = 4.4′,4″-nitrilotrisbenzoate; DMF = N,N-dimethylformamide), has been successfully achieved by solvothermal reaction of a C3-symmetric tricarboxytriphenylamine based ligand and Li(I) ion. The resulting framework features a binuclear Li(I) secondary building unit (SBU) and a rare 3.6-connected ant topology. Luminescence properties of 1 towards different metal ions and solvents have also been investigated systematically, with emission intensities significantly quenched towards Fe(III) ion and nitrobenzene (NB). The quenching mechanism has also been investigated in detail.A versatile Li(I)-based metal–organic framework with a rare 3.6-connected ant topology has been constructed by employing a C3-symmetric 4.4′,4″-nitrilotrisbenzoic acid, which exhibits relatively high luminescence selective detection for toxic nitrobenzene and Fe(III) ion in solution.

•A highly-thermostable microporous Zn(II) coordination polymer•High CO2 capacity and CO2/N2 selectivity•Understanding the sorption behavior at molecular level by GCMC simulationBy combining experiment with molecular simulation, the CO2 sorption performance of a 2D honeycomb layered coordination polymer, {[Zn2(bpydb)2(H2O)2](DMA)3(H2O)}n (1) (bpydb = 4,4′-(4,4′-bipyridine-2,6-diyl) dibenzoate) was systematically investigated. The desolvated 1 not only shows high CO2 capacity (72.5 cm3/g at 273 K and 42.9 cm3/g at 298 K) with a moderate high zero-coverage adsorption enthalpy (29.7 kJ/mol), but also exhibits excellent CO2/N2 selectivity around room temperature. To better understand the adsorption behaviors and adsorption sites for CO2 in 1, GCMC simulations were carried out, which indicate that the open metal sites between two adjacent layers account for the high CO2 sorption capacity and strong CO2 binding ability. Moreover, the thermal stability of 1 was further confirmed by the TGA and VT-PXRD, which indicate that 1 could be thermally stable up to 400 °C.The gas sorption behaviors of a Zn(II) 2D layered coordination polymer was investigated both experimentally and theoretically. The relevant results show that the coordination polymer possesses high CO2 sorption ability and CO2/N2 separation performance, which, from the GCMC simulation results, should be attributed to the open metal sites along with the suitable pore surroundings contribute.

To further explore the research of the coordination possibilities of lanthanide ions with m-/p-hydroxybenzoic acid isomers in the presence of chelating N-donor ligand 1,10-phenanthroline (phen), six lanthanide supramolecular frameworks based on 3- and 4-hydroxybenzoic acids, namely [Dy(m-L)(m-HL)(phen)]·H2O (1) (m-H2L = 3-hydroxybenzoic acid), [Ln(m-HL)3(phen)] (Ln = Gd for 2 and Tb for 3), [Ln(p-HL)3(phen)(H2O)] (Ln = Dy for 4, Gd for 5, and Tb for 6; p-H2L = 4-hydroxybenzoic acid), were synthesized and characterized. Structural analyses reveal that complex 1 has a two-dimensional (2-D) sheet structure while complexes 2 and 3 take the dinuclear structures in the 3-hydroxybenzoate derivatives. In the 4-hydroxybenzoate derivatives, complexes 4–6 are isostructural and incorporated by monomeric units. Finally, all the complexes exhibit three-dimensional (3-D) supramolecular frameworks (bcu net for 1; bct nets for 2, and 4–6; hex net for 3) with the aid of abundant hydrogen bonding, π⋯π and C–H⋯π interactions. The results reveal that the different positions of the –OH substituent and coordination modes of hydroxybenzoic acids adjust the final coordination networks. Moreover, the magnetic and luminescent properties of the complexes have also been investigated and discussed.The construction of six 3-D lanthanide supramolecular frameworks has been successfully achieved based on position isomers of hydroxybenzoic acids (m- and p-hydroxybenzoic acid) in the presence of 1,10-phenanthroline. Their diverse supramolecular structures can be well regulated by the different positions of the –OH substituent and coordination modes of hydroxybenzoic acids.

•Two magnetic 3-D LnIII MOFs constructed from tripodal multicarboxylate•Different infinite 1-D rod-shaped inorganic [Lnx(COO)y(H2O)z] SBUs•Offering effective means for constructing unique MOFsAssembly of a semi-rigid tripodal ligand, 3,5-bis(4-carboxyphenoxy)benzoic acid (H3bpa), with Ln2O3 (Ln = Dy for 1 and Er for 2) under hydrothermal condition produces two three-dimensional (3-D) lanthanide–organic frameworks (LnOFs), [Dy2(bpa)2(H2O)3] (1) and [Er4(bpa)4(H2O)6](H2O) (2). Single crystal X-ray diffraction indicates that LnOFs 1 and 2 involve different one-dimensional (1-D) rod-shaped metal-carboxylate secondary building units (SBUs), which are further extended to afford two different 3-D frameworks via the linkage of bpa3 − ligands. The results demonstrate that the diverse conformations and coordination modes of bpa3 − ligands play a key role on the formation of the final framework structures. Temperature-dependent magnetic susceptibility measurements reveal the presence of LnIII⋯LnIII ferromagnetic interactions in both LnOFs.The construction of two magnetic 3-D DyIII and ErIII lanthanide–organic frameworks has been successfully achieved based on 3,5-bis(4-carboxyphenoxy)benzoate, and their diverse framework structures can be well regulated by different infinite 1-D rod-shaped inorganic [Lnx(COO)y(H2O)z] SBUs.

Selective adsorption and separation of CO2 are of great importance for different target applications. Metal–organic frameworks (MOFs) represent a promising class of porous materials for this purpose. Here we present a unique MOF material, [Cu(tba)2]n (tba = 4-(1H-1,2,4-triazol-1-yl)benzoate), which shows high CO2 adsorption selectivity over CH4/H2/O2/Ar/N2 gases (with IAST selectivity of 41–68 at 273 K and 33–51 at 293 K). By using a critical point dryer, the CO2 molecules can be well sealed in the 1D channels of [Cu(tba)2]n to allow a single-crystal X-ray analysis, which reveals the presence of not only Cδ+—H···Oδ− bonds between the host framework and CO2 but also quadrupole–quadrupole (CO2δ−···δ+CO2) interactions between the CO2 molecules. Furthermore, [Cu(tba)2]n will suffer divergent kinetic and thermodynamic hydration processes to form its isostructural hydrate {[Cu(tba)2](H2O)}n and a mononuclear complex [Cu(tba)2(H2O)4] via single-crystal to single-crystal transformations.

Stability is a critical issue in practical applications of metal–organic frameworks (MOFs). These materials are usually destroyed by heating or exposure to chemicals, which cause them to reduce or even lose their porous nature. We report here a mesoporous 437-MOF material with perfect 1-D hexagonal channels of ca. 3 nm pore size, which shows both high thermal and chemical stability. The gas sorption capacity of desolvated 437-MOF can be improved by activating the material at higher temperatures. Remarkably, optimum porosity is achieved using a combined approach of heating the sample in boiling water followed by further heating. This unexpected observation can be ascribed to the synergistic effects of the external and internal surfaces of the porous crystalline material. An exploration of the possible applications of this material in supercapacitors shows a great potential for activated 437-MOF to be used as an electrode material as a result of its high surface area (ca. 2400 m2 g−1), hierarchical pore structure, and the pseudocapacitor contribution provided by doping with In.

Five isostructural lanthanide–organic coordination frameworks with a unique 3-D 5-connected (47.63)(43.65.82) network, namely, [Ln(phen)(L)]n (Ln = Dy for 1, Gd for 2, Ho for 3, Er for 4, and Tb for 5), have been prepared based on bridging 5-hydroxyisophthalic acid (H3L) and chelating 1,10-phenanthroline (phen) coligand. Significantly, the Dy(III) complex 1 is an organized array of single-molecular magnets (SMMs), with frequency-dependent out-of-phase ac susceptibility signals and magnetization hysteresis at 4 K. Further analysis of the magnetic results can reveal that the SMM behavior of 1 should arise from the smaller ferromagnetic interaction between the Dy(III) ions. Complex 1 was also characterized by X-ray absorption spectra, which give the clear X-ray magnetic circular dichroism signal.

This work presents a mesoporous DyIII metal–organic framework with two types of void cages (diameters: 4.4 and 2.8 nm), which can efficiently adsorb a variety of chemical pollutants, including toxic metals, iodine, and formaldehyde.

•Two unique 3D MnII MOFs with different self-interpenetrating topologies•Rigid/flexible ligand nature plays an important role in coordination construction.•Offering effective means for constructing unique coordination networksAssembly of two tripodal multicarboxylic ligands, namely rigid 3,4-bis(4-carboxyphenyl)-benzoic acid (H3L1) and flexible 3,5-bis(4-carboxyphenoxy)-benzoic acid (H3L2) with MnCl2 under hydrothermal conditions afforded two distinct metal-organic frameworks (MOFs), {[Mn3(L1)2(H2O)4](H2O)2}n (1) and {[Mn3(L2)2(H2O)4](H2O)4}n (2), respectively. Interestingly, both complexes possess different 3D networks of novel self-interpenetrating prototype, constructing from different 2D [Mn(COO)2]n polymeric motifs. Furthermore, the thermal and magnetic properties of 1 and 2 are studied.Two magnetic MnII MOFs with rigid or flexible tripodal multicarboxylate ligands have been successfully constructed, which exhibits the different self-interpenetrating topological networks.

•Two unique luminescent 3-D CdII MOFs with different topological nets•Reaction temperatures play important roles in coordination constructions.•Offering effective means for constructing diverse coordination networksTwo new 3-D Cd(II) coordination polymers (CPs) with 3,5-bi(4-carboxyphenoxy)-benzoic acid (H3L), namely [Cd3(L)2(H2O)4]·4H2O (1) and [Cd3(L)2(H2O)3]·2H2O (2), were successfully synthesized under hydrothermal condition at 140 °C and 180 °C, respectively. Complex 1 is constructed from 1-D (–Cd–O–)∞ rod-shaped SBUs (secondary building units) and ‘Y’-shaped L ligands. In complex 2, the 3-D network is mediated by 2-D [Cd(COO)2]n layered motifs and ‘T’ and ‘Y’-shaped L ligands. The results show that the reaction temperature plays a key role on the final structures of the complexes. The luminescent properties of the complexes have also been investigated.Two luminescent 3-D CdII MOFs based on a flexible tripodal multicarboxylate ligand and different SBUs have been successfully synthesized by controlling the reaction temperatures.

•A unique 3D (4,5,6)-connected LaIII network•The in situ formed benzene-1,2,3,4-tetracarboxylate ligand•Offering effective means for constructing unique coordination networksOne new 3-D open lanthanide–organic framework {[La2(L)1.5(H2O)4]∙2.75H2O}∞ (1) (L = benzene-1,2,3,4-tetracarboxylate) was synthesized and characterized by elemental analyses, IR spectrum, and single-crystal X-ray diffraction, respectively. Notably, 1,2-naphthalenedicarboxylic anhydride can be turned into benzene-1,2,3,4-tetracarboxylate (L) ligand upon an in situ reaction process under hydrothermal conditions. L ligand exhibited two different types of carboxyl coordination modes in 1, and bridged the lanthanum atoms to form a 2-D bilayer and then a 3-D open framework with (4,5,6)-connected (42.84) (32.44.52.62)4(32.45.53.64.7)2 topology. Moreover, luminescent properties of 1 have also been investigated.One new 3-D open lanthanide–organic framework {[La2(L)1.5(H2O)4]∙2.75H2O}∞ (1) (L = benzene-1,2,3,4-tetracarboxylate) has been hydrothermally synthesized through in situ ligand formation, which exhibited an unusual (4,5,6)-connected (42.84) (32.44.52.62)4(32.45.53.64.7)2 topology.

A new Cd(II) coordination polymer [Cd4(μ3-OH)2(L)2(H2O)3]n (1) is constructed from an unexplored non-planar trigonal tricarboxyl ligand 3,4-bi(4-carboxyphenyl)-benzoic acid (H3L), which exhibits an unusual (4,10)-connected (3.45)(34.49.512.617.72.8) topological net based on the tetranuclear [Cd4(μ3-OH)2] secondary building units (SBUs). The elaborate modification of organic tectons provides a new perspective on the design and synthesis of highly-connected coordination networks. Additionally, the thermal stability and luminescence of the crystalline material have also been investigated.

A novel coordination polymer [La(L)(H2O)]n (1) has been prepared by hydrothermal reaction of 5-hydroxyisophthalic acid (H3L) with La(NO3)3·6H2O, which exhibits an unusual three-dimensional (3D) (6,6)-connected nia net with Point (Schläfli) symbol of (412.63)(49.66). Meanwhile, a two-dimensional (2D) (3,6)-connected (32.4)(34.43.52.65.7) coordination network {[Ho2(HL)3(H2O)2]·H2O}n (S1) was also obtained with partially deprotonated HL2– ligand. Comparison of the structural differences between 1 and S1 suggests that the different metal sources play an important role in the construction of such coordination networks.Two coordination polymers, [La(L)(H2O)]n (1) and {[Ho2(HL)3(H2O)2]·H2O}n (S1) (H3L = 5-hydroxyisophthalic acid), have been prepared. Complex 1 exhibits the nia topological net with Point (Schläfli) symbol of (412.63)(49.66), whereas complex S1 has a 2D (3,6)-connected (32.4)(34.43.52.65.7) topology. Remarkably, complex 1 is the first lanthanide network with the hydroxyl group of 5-hydroxyisophthalic acid coordinating to the metal atoms.Highlights► A unique 3D LaIIInia network with (412.63)(49.66) topology. ► Structure modulation driven by different metal sources. ► The hydroxyl group of 5-hydroxyisophthalic acid coordinating with LaIII

A series of six Ag(I) and Zn(II) coordination polymers, namely, [Ag2(ndc)]∞ (1), {[Zn(ndc)(H2O)](H2O)}∞ (2), {[Ag2(ndc)(4bpy)2][Ag(4bpy)(H2O)](ClO4)(H2O)2}∞ (3), [Zn5(ndc)4(4bpy)2(μ3-OH)2]∞ (4), {[Ag(ndc)(abp)][Ag(abp)](H2O)3}∞ (5), and {[Zn2(ndc)2(abp)(H2O)2](H2O)2}∞ (6), have been prepared by using 2,3-naphthalenedicarboxylic acid (H2ndc), an analogue of 1,2-benzenedicarboxylic acid (H2bdc), and different 4,4′-bipyridyl-like bridging co-ligands 4,4′-bipyridine (4bpy) and trans-4,4′-azobis(pyridine) (abp). The initial complexes 1 and 2 display the unusual two-dimensional (2-D) five-connected (48.62) and the 2-D three-connected (4.82) coordination networks, respectively. When two comparable rod-like linkers 4bpy and abp (with different N,N′-donor separations of the molecular backbones of ca. 7 and 9 Å) are further introduced, two one-dimensional (1-D) complexes 3 and 5, a three-dimensional (3-D) coordination framework 4 with (43)(43.63)(43.65.82)(44.64.82)(410.65) topology and a 2-D 63 layered coordination polymer 6 are constructed. A structural comparison of these complexes with those based on the structurally related bdc ligand suggests that the extended π-conjugated system of ndc with different electronic nature and steric bulk play an important role in constructing the supramolecular architectures for 1–6, which are also regulated by different bridging N-donor co-ligands and metal ions. Moreover, complexes 1–6 show strong solid-state luminescence emissions at room temperature that mainly originate from the intraligand transitions of ndc.

A series of three-dimensional (3-D) lanthanide–organic frameworks (LnOFs), with the general formula [Ln2(H–L)3(H2O)]∞ (H–L = N-protonated 2,6-dihydroxypyridine-4-carboxylate; LnIII = LaIII for 1, PrIII for 2, NdIII for 3, and SmIII for 4), have been synthesized under hydrothermal conditions. X-Ray diffraction and energy dispersive X-ray spectroscopy (EDS) analyses reveal that complexes 1–4 are isostructural and exhibit the unique 3-D coordination framework with (4,5,7)-connected network topology, in which the H–L ligands adopt the μ4- and μ5-bridging fashions. Remarkably, thermogravimetric analysis of the crystalline materials shows their exceptionally high thermal stability (up to 530 °C), which should originate from the dense nature of the packing lattices and the unusual network structures.

A series of novel three-dimensional (3-D) lanthanide−organic frameworks (LnOFs), with the general formula [Ln2(H-L)3(H2O)4]∞ (Ln = DyIII for 1, GdIII for 2, TbIII for 3, EuIII for 4, and HoIII for 5; H-L = N-protonated 2,6-dihydroxypyridine-4-carboxylate), have been synthesized under hydrothermal conditions. X-ray structural analysis reveals that complexes 1−5 are isostructural and show the unique 3-D coordination framework with a trinodal (3,4,5)-connected (4.62)(42.6)(42.84)(43.6.86)(42.65.83) net topology, in which the H-L ligands adopt different μ4- and μ3-bridging forms. Variable-temperature magnetic susceptibility studies reveal that complexes 1−3 and 5 show ferromagnetic behaviors. Notably, complex 1 (DyIII) is the first instance leading to ferromagnetic coupling for a lanthanide ion through a spin-polarization mechanism. The alternating current (ac) signal observed for 1 and 5 should originate from the long-range ferromagnetic ordering, or it could reflect the splitting of the J multiplet for DyIII or HoIII under a low symmetry crystal field, which would give rise to slow relaxation of the magnetization. Additionally, thermal stability of these crystalline materials has also been investigated by thermogravimetric analysis of mass loss.

The reaction of AgClO4·6H2O with (+/−)-trans-epoxysuccinic acid (H2tes) in the presence of 2,6-dimethylpyridine afforded a three-dimensional (3-D) AgI coordination polymer [Ag2(tes)]∞ (1), which exhibits an unusual 5-connected self-penetrating (44·66)2 topological net (tes = (+/−)-trans-epoxysuccinate). Comparison of the structural differences with our relevant finding, a two-dimensional (2-D) (4,8)-connected (45·6)2(418·610) coordination polymer [Ag4(ces)2]∞ (S1) (ces = cis-epoxysuccinate), suggests that the carboxyl configuration on the ternary ring backbone of H2tes or H2ces ligand plays an important role in the construction of coordination networks.Highlights► A unique 3-D AgI complex with the 5-connected self-penetrating (44·66)2 topology. ► Carboxyl configurations play an important role in coordination construction. ► Offering effective means for constructing unique coordination networks.Graphical abstractA unique 3-D AgI coordination polymer [Ag2(tes)]∞ (tes=(+/−)-trans-epoxysuccinate), exhibiting an unusual 5-connected self-penetrating (44•66)2 topology, is presented. Comparison of the structural differences with our relevant finding suggests that the carboxyl configuration on the ternary ring backbone of ligands plays an important role in the construction of such coordination networks.

Two CuII coordination complexes {[Cu(ces)(H2O)2](H2O)0.5}n (1) and [Cu15(dhs)6(OH)6(H2O)10](H2O)20 (2) have been synthesized from cis-epoxysuccinic acid (cis-H2ces) and CuII perchlorate under different pH conditions (ces = cis-epoxysuccinate and dhs = 2,3-dihydroxysuccinate), and fully characterized by IR spectra, elemental analyses, as well as single crystal and powder X-ray diffraction techniques. Notably, when the reaction was performed at pH above about 7.4, a one-dimensional (1-D) helical chain complex 1 is formed, whereas a neutral isolated Cu15 nanocluster 2 is generated when the pH value is decreased to the range of about 6.6−7.3, being concomitant with in situ SN2 ring-cleavage reaction of cis-H2ces to form (2S,3S)- and (2R,3R)-H4dhs. Further, extended supramolecular architectures are constructed via secondary interactions in both structures. The magnetic properties of 1 and 2 have also been studied in detail, showing that 1 is an antiferromagnetic helical chain of S = 1/2 spins and 2 possesses an S = 3/2 spin ground state.

To systematically explore the influence of the pyridyl N-donor spatial positions of benzotriazol-1-yl-based pyridyl tectons on structural assemblies of coordination polymers, three closely related ligands, 1-(2-pyridylmethyl)-1H-benzotriazole (2-pbt), 1-(4-pyridylmethyl)-1H-benzotriazole (4-pbt), and 1-(3-pyridylmethyl)-1H-benzotriazole (3-pbt), were designed and prepared. Their reactions with CuI under hydrothermal conditions afforded three new copper(I)-iodide coordination polymers, namely, [CuI(2-pbt)]∞ (1), [Cu2I2(4-pbt)]∞ (2), and [Cu3I3(3-pbt)]∞ (3). Single-crystal X-ray diffraction analysis shows that 1 has a two-dimensional (2D) (4,4) sheet structure containing rhomboid [Cu2I2] dimeric units, which are further extended to form a three-dimensional (3D) framework by interlayer C–H⋯π supramolecular interactions. Complexes 2 and 3, with one-dimensional (1D) looped-chain [Cu2I2]n and 1D staircase double-chain [Cu3I3]n copper(I)-iodide arrays, show an unusual 3D six-connected self-penetrating rob net with the Schläfli symbol of (48.66.8) and a 3D four-connected homochiral diamond net, respectively. The results reveal that the different spatial positions of pyridyl N-donors in this series of ligands play an important role in constructing coordination polymers 1–3. Moreover, the photoluminescent properties and thermal stability of 1–3 in the solid state have also been investigated.

The coordination possibilities of flexible heteroalicyclic ligands with transition metals have been explored. Five CuII, MnII, and CdII coordination polymers with the fully deprotonated tetrahydrofuran-2,3,4,5-tetracarboxylate (L) ligand were synthesized and characterized, sometimes incorporating different auxiliary ligands: {[Cu2(L)(H2O)](H2O)1.42}∞ (1), {[Cu2(L)(2bpy)(H2O)2](H2O)2}∞ (2), {[Cu2(L)(phen)(H2O)2](H2O)1.5(CH3OH)0.25}∞ (3), {[Mn2(L)(phen)2(H2O)](H2O)2}∞ (4), and {[Cd2(L)(phen)2(H2O)](H2O)2}∞ (5) (2bpy = 2,2′-bipyridine and phen = 1,10-phenanthroline). The structural analysis related to 1–5 reveals that the fully deprotonated L ligand displays versatile coordination modes, which result in the generation of a fairly complicated three dimensional (3D) framework for 1 with a Schläfli symbol of (43·67)(46·64), two isostructural two dimensional (2D) puckered layers for 2 and 3 with the decorated binodal (3,5)-connected (3·52)2(32·53·64·7) topology, and two isostructural one dimensional (1D) ribbon-like chains for 4 and 5, respectively. The present work indicates that, in comparison with the rigid aromatic multicarboxylate ligands, tetrahydrofuran-2,3,4,5-tetracarboxylate (L), a heteroalicyclic multicarboxylate ligand, has richer coordination modes and a more flexible ring skeleton, which may remain largely unexpected in the process of constructing metal–organic frameworks (MOFs) and make it more difficult to predict and control the final coordination polymers. Magnetic susceptibility measurements demonstrate that complexes 1 and 4 exhibit antiferromagnetic coupling, whereas 2 and 3 show ferromagnetic coupling, with the corresponding J values of −23.62 cm−1 for 1, 5.18 cm−1 for 2, 3.90 cm−1 for 3, and −0.79 cm−1 for 4. Moreover, complex 5 displays solid blue emission originating from an intraligand π → π* transition of the auxiliary phen ligand.

A series of six CdII coordination complexes have been prepared by using naphthalene-2,3-dicarboxylic acid (H2ndc), an analogue of 1,2-benzenedicarboxylic acid (H2bdc), and different N-donor auxiliary co-ligands (chelating or bridging), namely, [Cd(ndc)]∞ (1), {[Cd2(ndc)2(2bpy)2(H2O)2](CH3OH)0.5}2 (2), [Cd2(ndc)2(phen)2]∞ (3), {[Cd(ndc)(4bpy)0.5(H2O)2](H2O)}∞ (4), {[Cd(ndc)(abp)(H2O)](H2O)}∞ (5), and {[Cd(ndc)(bpp)2](H2O)3}∞ (6) (ndc = naphthalene-2,3-dicarboxylate, 2bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, 4bpy = 4,4′-bipyridine, abp = trans-4,4′-azobis(pyridine), and bpp = 1,3-bis(4-pyridyl) propane). The initial complex 1 shows a two-dimensional (2-D) (44.62) coordination network. 2 and 3 possess tetranuclear and one-dimensional (1-D) structures due to the incorporation of auxiliary chelating co-ligands 2bpy and phen, respectively, which are further interlinked via secondary interactions such as hydrogen bonding and aromatic stacking to result in higher-dimensional supramolecular networks. When the 4,4′-dipyridyl-type bridging co-ligands 4bpy, abp, and bpp (with different N,N′-donor separations of the molecular backbones from ca. 7−10 Å) were used as the additional rod-like linkers, a 2-D (3,4)-connected (42.6)(42.63.8) layered coordination net 4 as well as a three-dimensional (3-D) coordination framework 5 with an unusual 4-connected irl topology (42.63.8) and a homochiral 3-D diamond (dia) network 6 were obtained. A structural comparison of these complexes with those based on the structurally related ligand 1,2-benzenedicarboxylate (bdc) suggests that the extended π-conjugated system of ndc with a different electronic nature and steric bulk plays an important role in the construction of supramolecular architectures for 1−6, which can also be well regulated by the different chelating or bridging N-donor co-ligands. Moreover, complexes 1−6 exhibit strong solid-state luminescence emissions at room temperature, which mainly originate from the intraligand π → π* transitions of ndc.

The reaction of AgClO4 with 2-naphthol-5-carboxylic acid (HL) and hexamethylenetetramine (hmt) in the presence of 2,6-dimethylpyridine afforded a photoluminescent three-dimensional (3D) AgI polymer {[Ag6(L)(μ3-hmt)2(μ4-hmt)2(ClO4)](ClO4)4(H2O)}∞ (1), which exhibited an unusual (3,4)-connected (6·7·8)2(4·6·7)2(4·7·8)2(72·8)2(62·7·83)(62·72·8·10) topological network (L = 2-naphthol-5-carboxylate). Moreover, the luminescent properties of 1 have been briefly investigated.A photoluminescent three-dimensional (3D) AgI coordination polymer {[Ag6(L)(μ3-hmt)2(μ4-hmt)2(ClO4)](ClO4)4(H2O)}∞ (1), exhibiting an unusual (3,4)-connected (6·7·8)2(4·6·7)2(4·7·8)2(72·8)2(62·7·83)(62·72·8·10) topological network, has been successfully constructed (L = 2-naphthol-5-carboxylate and hmt = hexamethylenetetramine). Moreover, the luminescent properties of 1 have also been investigated.

The in situ reaction of AgClO4·6H2O with 5,6-dihydro-1,4-dithiin-2,3-dicarboxylic anhydride in the presence of lithium hydroxide afforded a photoluminescent three-dimensional (3-D) AgI coordination polymer, [Ag2(L)]∞ (1), which exhibited an unusual trinodal 6-connected (412.63)2(49.66) topological net (L = 5,6-dihydro-1,4-dithiin-2,3-dicarboxylate). Moreover, the luminescent/thermal properties of 1 have also been briefly investigated.A photoluminescent three-dimensional (3-D) AgI coordination polymer [Ag2(L)]∞ (1), exhibiting an unusual trinodal 6-connected (412.63)2(49.66) topological network, has been successfully constructed by in situ reaction of 5,6-dihydro-1,4-dithiin-2,3-dicarboxylic anhydride with AgClO4·6H2O (L = 5,6-dihydro-1,4-dithiin-2,3-dicarboxylate).

The reaction of PdCl2 with a bulky acridine-based ligand afforded a novel PdII complex [Pd2(L)Cl4(CH3CN)](CH3CN)0.5 (1) (L = 9-[3-(2-pyridyl)pyrazol-1-yl]-acridine) exhibiting intra- and intermolecular C–H···Pd H-bonding interactions, which was characterized by elemental analysis, IR, and single-crystal X-ray diffraction analysis (triclinic system, space group P-1, with a = 8.774(6), b = 12.742(9), c = 14.149(10) Å, α = 67.573(11), β = 72.601(11), γ = 83.674(12)°, V = 1395.4(17) Å3, and Z = 2). Complex 1 has an asymmetrical dinuclear structure, which are further assembled into a one-dimensional (1D), and then two-dimensional (2D) network via intra- and/or inter-molecular C–H···Pd and C–H···Cl H-bonding interactions from different crystallographic directions. This work offers a new example in which the N donor of the acridine ring coordinates to a metal ion in a supramolecular coordination system.

Two new cobalt(II) coordination polymers with a pyridyl/benzimidazol-1-yl-based ligand, namely 1-(4-pyridylmethyl)-1H-benzimidazole (L), were synthesized and characterized structurally by single crystal X-ray diffraction as [Co(L)2(SCN)2]∞ (1) and [Co(L)2(N3)2]∞ (2). Complex 1 has a three-dimensional twofold interpenetrating diamondoid network, while 2 possesses a one-dimensional chain structure, which is further interlinked into a higher-dimensional supramolecular framework by hydrogen-bonding interactions. The structural differences between complexes 1 and 2 are attributable to the different auxiliary ligands, SCN− for 1 and N3− for 2. The luminescent properties of the complexes and the free ligand have been investigated.Two new Co(II) complexes having 3-D and 1-D structures have been successfully prepared through auxiliary ligand-controlled self-assembly reactions of Cobalt salts with a pyridyl/benzimidazol-1-yl-based ligand. Moreover, luminescent properties of these complexes and the corresponding ligand have also been investigated.

To explore the influence of the anthracene ring skeleton, with a large conjugated π-system, on the structures and properties of its complexes, two MnII complexes with anthracene-9-carboxylate ligand were synthesized and structurally characterized: {[Mn(L)2(H2O)2](H2O)}∞ (1) and [Mn2(L)4(phen)2(μ-H2O)](CH3OH) (2) (L = anthracene-9-carboxylate and phen = 1,10-phenanthroline). Complex (1) has a one-dimensional (1D) chain structure that is further assembled to form a two-dimensional (2D) sheet, and then an overall three-dimensional (3D) network by π···π stacking and/or C–H···π interactions. Complex (2) makes a dinuclear structure by incorporating the chelating phen ligand, which is further interlinked via inter-molecular π···π stacking and C–H···π interactions to generate a higher-dimensional supramolecular network along the different crystallographic directions. The results reveal that the bulky anthracene ring skeleton in L, by virtue of intra- and/or inter-molecular π···π stacking and C–H···π interactions, plays an important role in the formation of complexes (1) and (2). The magnetic properties of (1) and (2) were further investigated. As expected, the very long inter-metallic separations result in weak magnetic coupling, with the corresponding coupling constant values of J = −10 cm−1 for (1) and J = −2.46 cm−1 for (2).

Incorporating the in situ formed size-matching molecular building blocks (MBBs) into the open channels will remarkably improve the robustness and gas sorption performance of an evacuated metal–organic framework. As a result, such MBBs can transfer the open metal sites from the framework walls to the channel centers and separate the large channels into multiple smaller voids, leading to a molecular sieving effect and high-performance gas-separation of the modified material.

A terbium(III) lanthanide–organic framework (534-MOF-Tb) with a green-emission signal was successfully obtained by the solvothermal reaction of Tb3+ ions with the organic ligand H3TBOT (2,4,6-tris[1-(3-carboxylphenoxy)ylmethyl]mesitylene). 534-MOF-Tb contains microporous quadrangle channels with accessible Lewis-base sites and coordinated water molecules, which are feasible to anchor and recognise multifarious analytes. It can serve as a recyclable multi-responsive sensing material for detecting Fe3+, MnO4−, Cr2O72−, and p-nitrotoluene (4-NT). Significantly, this is the first reported MOF-based sensor for detecting explosive 4-NT. Moreover, the mechanism of the selective luminescence quenching response for Fe3+, MnO4−, Cr2O72− or 4-NT can be mainly explained in terms of the competition between the absorption of the light source energy and the electronic interaction between the analyte and the TBOT ligand.

A flexible bidentate polyaromatic acid ligand 4,4′-oxybis(benzoic acid) (H2oba) was used for the construction of a novel luminescent Tb(III)-based metal–organic framework (MOF), namely {(Me2NH2)[Tb(OBA)2]·(Hatz)·(H2O)1.5}n, with 3-amino-1,2,4-triazole (Hatz) as the template reagent. In the structure of the Tb-MOF, there co-exist single-stranded and double-stranded helical chains along the c axis, and the overall network shows a three-fold interpenetrated qtz net. This MOF is capable of selectively sensing Fe3+ and Al3+ ions in water via quenching the luminescence and tuning the emission ratio between the ligand-based and metal-based luminescence, respectively. More importantly, this MOF can realize fast detection for p-xylene (PX) vapor with a response time of less than 10 s and 40% fluorescence enhancement, while nitrobenzene (NB) vapor could lead to a quenching effect in 10 min with a 75% quenching efficiency. Remarkably, this is the first example of a multi-responsive luminescent Tb-MOF sensor for Fe3+ and Al3+ ions and VOC vapor detection. In connection to these, the probable sensing mechanisms were also discussed in this paper.

A series of six Ag(I) and Zn(II) coordination polymers, namely, [Ag2(ndc)]∞ (1), {[Zn(ndc)(H2O)](H2O)}∞ (2), {[Ag2(ndc)(4bpy)2][Ag(4bpy)(H2O)](ClO4)(H2O)2}∞ (3), [Zn5(ndc)4(4bpy)2(μ3-OH)2]∞ (4), {[Ag(ndc)(abp)][Ag(abp)](H2O)3}∞ (5), and {[Zn2(ndc)2(abp)(H2O)2](H2O)2}∞ (6), have been prepared by using 2,3-naphthalenedicarboxylic acid (H2ndc), an analogue of 1,2-benzenedicarboxylic acid (H2bdc), and different 4,4′-bipyridyl-like bridging co-ligands 4,4′-bipyridine (4bpy) and trans-4,4′-azobis(pyridine) (abp). The initial complexes 1 and 2 display the unusual two-dimensional (2-D) five-connected (48.62) and the 2-D three-connected (4.82) coordination networks, respectively. When two comparable rod-like linkers 4bpy and abp (with different N,N′-donor separations of the molecular backbones of ca. 7 and 9 Å) are further introduced, two one-dimensional (1-D) complexes 3 and 5, a three-dimensional (3-D) coordination framework 4 with (43)(43.63)(43.65.82)(44.64.82)(410.65) topology and a 2-D 63 layered coordination polymer 6 are constructed. A structural comparison of these complexes with those based on the structurally related bdc ligand suggests that the extended π-conjugated system of ndc with different electronic nature and steric bulk play an important role in constructing the supramolecular architectures for 1–6, which are also regulated by different bridging N-donor co-ligands and metal ions. Moreover, complexes 1–6 show strong solid-state luminescence emissions at room temperature that mainly originate from the intraligand transitions of ndc.

Stability is a critical issue in practical applications of metal–organic frameworks (MOFs). These materials are usually destroyed by heating or exposure to chemicals, which cause them to reduce or even lose their porous nature. We report here a mesoporous 437-MOF material with perfect 1-D hexagonal channels of ca. 3 nm pore size, which shows both high thermal and chemical stability. The gas sorption capacity of desolvated 437-MOF can be improved by activating the material at higher temperatures. Remarkably, optimum porosity is achieved using a combined approach of heating the sample in boiling water followed by further heating. This unexpected observation can be ascribed to the synergistic effects of the external and internal surfaces of the porous crystalline material. An exploration of the possible applications of this material in supercapacitors shows a great potential for activated 437-MOF to be used as an electrode material as a result of its high surface area (ca. 2400 m2 g−1), hierarchical pore structure, and the pseudocapacitor contribution provided by doping with In.

Metal–organic frameworks (MOFs), as a class of adjustable porous crystalline materials, have received considerable attention in recent years. In this study, starting from an unstable MIL-88 type Co(II)-MOF as the prototype structure, two isoreticular stabilized MOFs with similar structural features but different water/thermal stabilities and acetylene sorption behaviors were prepared, which can be modulated by incorporating different functional brackets in the pores. MOF 1 equipped with open metal sites (OMSs) decomposed quickly in water solution, while the free N-donor functionalized MOF 2 could be stable in water with improved thermostability. The gas sorption study reveals that activated material 2 has a significantly enhanced acetylene uptake capacity with a lower Qst value than those of activated 1, showing a 79% increase (242 vs. 135 cm3 g−1) at 273 K and 91% increase (165 vs. 86 cm3 g−1) at 298 K. The acetylene uptake capacity of activated material 2 is extraordinarily high among MOFs without OMSs, and is even comparable to some famous MOFs with much stronger C2H2 binding ability which however require considerably higher energy for regeneration. The experimental results were further confirmed by the molecular mechanics (MM) calculations, grand canonical Monte Carlo (GCMC) simulations and density functional theory (DFT) studies.