Four new 3D uranyl complexes, [(UO2)2(H2O)(ipa)2]·9H2O (1), [(UO2)2(H2O)(nip)2]·H2O·Et3NH (2), [(UO2)2(H2O)(aip)2]·Et3NH (3) and [(UO2)(hip)]2·17H2O (4) (H2ipa = isophthalic acid, H2nip = 5-nitroisophthalic acid, H2aip = 5-aminoisophthalic acid, H2hip = 5-hydroxyisophthalic acid, Et3N = triethylamine), were hydrothermally synthesized. Structural analyses reveal that compounds 1–4 consist of pentagonal bipyramidal uranyl monomers bridged via acid inkers to form a structural motif, [(UO2)2L2], serving as the foundation of the 3D framework. Two structural motifs adopt different arrangement modes to connect to two types of chains. For 1–3, uranium atoms and carboxyl groups being from two types of chains respectively are coordinated to build similar 3D frameworks, while for 4, one type of chain links to the 3D architecture by the bond of the uranium atoms and –OH of the 5-hydroxyisophthalic acid ligand. The different guest molecules and structure assemblies displayed by the four compounds are a function of the variation of substituent groups of 5-X-1,3-benzenedicarboxylic acid (X = –H, –NO2, –NH2, –OH). Furthermore, the photocatalytic properties of 2 and 4 for degradation of rhodamine-B (RhB) upon xenon lamp irradiation have been examined. Elemental analysis, infrared spectroscopy, DRS and luminescence properties were also discussed.

Hydrothermal reactions yielded five new Ce(III) sulfate–tartrate-based MOFs, namely, α-[Ce2(H2O)2(L-tar)2(SO4)]·4H2O 1, α-[Ce2(H2O)2(D-tar)2(SO4)]·4H2O 2, β-[Ce2(H2O)2(L-tar)2(SO4)]·4H2O 3, β-[Ce2(H2O)2(D-tar)2(SO4)]·4H2O 4 and Ce2(H2O)3(L/D-tar)(SO4)25. The two α-enantiomorphs (1, 2) crystallize in the polar monoclinic C2 space group, and the two β-enantiomorphs (3, 4) crystallize in the non-polar orthorhombic space group P21212, while 5 crystallizes in the monoclinic space group P21/c. The acentric MOFs 1–4 belong to the 3∞{2∞[M2(H2O)x(tar)b2]Ap}·nH2O family (hereby A = SO42−), and the [Ce2(tar)2] dimeric motifs rig up the 2D positively charged 2∞[Ce2(H2O)2(tar)2]2+ networks of a four-connected uninodal (42·64) topology, which are further pillared by sulfate anions into the 3∞{2∞[Ce2(H2O)2(tar)2](SO4)} framework of the (4,5)-connected dinodal (42·64)(42·67·8) topology with the lattice water molecules in the tunnels. Within 5, the [Ce(tar)] motifs rig up the 2D 2∞[Ce2(H2O)3(tar)]4+ patterns, which were stabilized by sulfate anions to form a 2D 2∞[Ce2(H2O)3(tar)(SO4)]2+ layer of a (3,4)-connected bi-nodal (63)(66) topology, and the 2D layers are pillared by additional sulfate anions into the 3D 3∞{2∞[Ce2(H2O)3(L/D-tar)(SO4)]SO4} framework of an unprecedented (3,4,5,6)-connected penta-nodal (4·62)(4·65)(4·67·82)(44·62)(45·68·82) topology. The results suggest that the acentricity of the 3∞{2∞[M2(H2O)x(tar)b2]Ap}·nH2O MOF is crucially determined by the tartrate forms incorporated in the 2D 2∞[M2(H2O)x(tar)b2] sheet, and the distances between the 2D sheets are tunable by the judicious selection of the pillaring auxiliary ligands. The polar α-MOFs (1, 2) display a promising ferroelectricity with a remnant polarization (Pr) of ca. 0.158 μC cm−2 for 1 (ca. 0.323 μC cm−2 for 2), a coercive field (Ec) of ca. 27.05 kV cm−1 for 1 (ca. 42.00 kV cm−1 for 2), and saturation of the spontaneous polarization (Ps) occurs at ca. 0.335 μC cm−2 for 1 (ca. 0.400 μC cm−2 for 2). The magnetic behaviors of the title compounds obey a modified Curie–Weiss law χ = χTIP + C/(T − θ) with χTIP = 200–230 × 10−6 cm3 mol−1, C = 0.228–0.329 cm3 K mol−1, θ = −0.03– −0.06 K, and the decrease of χMT with the lowering temperature and the negative value of θ may be due to the populations of the Stark levels and/or the possible antiferromagnetic interactions between the Ce3+ ions. Furthermore, the title complexes were subjected to microelemental analyses, IR spectroscopic measurements and thermal analyses, and the results are also discussed.

Two lanthanide pyridine-2,4,6-tricarboxylate coordination polymers [Ln2(H2O)9(ptc)2]·3H2O (Ln = Dy(1), Yb(2); H3ptc = pyridine-2,4,6-tricarboxylic acid) have been synthesized and structurally characterized by single-crystal X-ray diffraction. The compound 1 and 2 is isostructural, and the feature of structure is a centrosymmetric tetra-nuclear unit, which is assembled into a 3D supra-molecular architecture via extensively hydrogen bonding interaction. The luminescence experiments show that compound 1 exhibit the typical luminescence of Dy3+ ion in the visible region. Besides luminescence, the magnetic properties of 1 and 2 were investigated and indicated the anti-ferromagnetic couplings between the Ln(III) ions.Graphical abstractThe supramolecular architectures of two isostructural lanthanide pyridine-2,4,6-tricarboxylate, [Ln2(H2O)9(ptc)2]·3H2O (Ln = Dy(1), Yb(2); H3ptc = pyridine-2,4,6-tricarboxylic acid) exhibit a centrosymmetric tetra-nuclear unit, and the magnetic characterizations suggest anti-ferromagnetic couplings between the Ln(III) ions.Highlights► Two lanthanide pyridine-2,4,6-tricarboxylate complexes have presented. ► The feature of 1 and 2 is a centrosymmetric tetra-nuclear unit. ► The magnetic properties of 1 and 2 indicate the anti-ferromagnetic coupling.

Two new lanthanide-pyridine-2,4,6-tricarboxylate coordination polymers [Pr(H2O)3(ptc)]⋅H2O (1) and [Tb2(H2O)9(ptc)2]·3H2O (2) (H3ptc = pyridine-2,4,6-tricarboxylic acid) have been synthesized and structurally characterized by single crystal X-ray diffraction. The compound (1) crystallize as 2D layer, which are further engaged in hydrogen bonding leading to a novel 3D supramolecular architecture. Complex (2) exists as a centrosymmetric tetranuclear unit, which are assembled into a 3D supramolecular architecture via extensively hydrogen bonding interaction. The luminescence experiments show that Pr(III) and Tb(III) compounds exhibit typical luminescence in the visible region. Besides luminescence, the magnetic properties of (1) and (2) were investigated and indicate the anti-ferromagnetic couplings between the Ln(III) ions.Graphical abstractHighlights► 1 is a 2D herringbone-like topological nets. ► 2 is a centrosymmetric tetranuclear unit. ► The magnetic properties of 1 and 2 indicate the anti-ferromagnetic couplings.

A new Mn(II) complex formulated as [Mn(bpy)(H2O)4]2[Mn2(bpy)2(pdtc)2]·14H2O (1) (where H4pdtc=pyridine-2,3,5,6-tetracarboxylic acid, bpy=2,2′-bipyridine) has been prepared and characterized by IR spectroscopy, elemental analysis and single crystal X-ray diffraction. Complex 1 is tetranuclear and composed of a [Mn2(bpy)2(pdtc)2]4− anion and two [Mn(bpy)(H2O)4]2+ cations. The particular interest of complex 1 is the formation of a centrosymmetric water cluster (H2O)12 included a chair-shaped hexamer and two trimer clusters. The tetra-nuclear units are further aggregated by hydrogen bonding with (H2O)12 clusters and π···π stacking interactions to form a 3D supramolecular architecture.

Four new Cu(II) complexes {[Cu4(bpy)4(OH)4(H2O)2]}(NO3)2(C7H5O2)2·6H2O 1, {[Cu4(bpy)4(OH)4(H2O)2]}(NO3)2(C5H6O4)·8H2O 2, {[Cu4(bpy)4(OH)4(H2O)2]}(C5H6O4)2·16H2O 3 and {[Cu6(bpy)6(OH)6(H2O)2]}(C8H7O2)6·12H2O 4 were synthesized (bpy = 2,2′-bipyridine, H2(C5H6O4) = glutaric acid, H(C7H5O2) = benzoic acid, H(C8H7O2) = phenyl acetic acid). The building units in 1–3 are the tetranuclear [Cu4(bpy)4(H2O)2(μ2-OH)2(μ3-OH)2]4+ complex cations, and in 4 the hexanuclear [Cu6(bpy)6(H2O)2(μ2-OH)2(μ3-OH)4]6+ complex cations, respectively. The tetra- and hexanuclear cluster cores [Cu4(μ2-OH)2(μ3-OH)2] and [Cu6(μ2-OH)2(μ3-OH)4] in the complex cations could be viewed as from step-like di- and trimerization of the well-known hydroxo-bridged dinuclear [Cu2(μ2-OH)2] entities via the out-of-plane Cu–O(H) bonds. The complex cations are supramolecularly assembled into (4,4) topological networks via intercationic π⋯π stacking interactions. The counteranions and lattice H2O molecules are sandwiched between the 2D cationic networks to form hydrogen-bonded networks in 1–3, while the phenyl acetate anions and the lattice H2O molecules generate 3D hydrogen-bonded anionic framework to interpenetrate with the (4,4) topological cationic networks with the hexanuclear complex cations in the channels. The ferromagnetic coupling between Cu(II) ions in the [Cu4(μ2-OH)2(μ3-OH)2] cores of 1–3 is significantly stronger via equatorial-equatorial OH− bridges than via equatorial-apical ones. The outer and the central [Cu2(OH)2] unit within the [Cu6(μ2-OH)2(μ3-OH)4] cluster cores in 4 exhibit weak ferromagnetic and antiferromagnetic interactions, respectively. Results about i.r. spectra, thermal and elemental analyses are presented.

Three new pyridine-2,4,6-tricarboxylic acid (H3ptc) complexes, [Mn3(ptc)2(H2O)9]n (1), [Co3(ptc)2(H2O)2]n (2), and [Co(bpy)(H2O)4]n[Co(ptc)(H2O)]2n (3) were hydrothermally synthesized and characterized by single-crystal X-ray diffraction methods, elemental analyses, IR spectroscopy, thermal analyses and magnetic measurements along with ferroelectric measurement for 1 were carried out. Compound 1 crystallizes in the acentric space groupCc and exhibits significant ferroelectricity (a remnant polarization Pr = 0.0188 μC cm−2, coercive field Ec = 9 kV cm−2, saturation of the spontaneous polarization Ps = 0.1326 μC cm−2). To the best of our knowledge, 1 represents the first example of a pyridine-2,4,6-tricarboxylato coordination polymer that exhibits possible ferroelectric behavior. Within 1, both seven- and six-coordinated Mn2+ ions are bridged by ptc3− anions to generate 1D bands, which are assembled into a 3D supramolecular architecture through extensive hydrogen bonds. The CoN2O4 and CoO6 octahedra in 2 are corner-shared to form 2D sigmoid layers, which are further interconnected by organic linkers into topologically 3D MOF of (32·46·56·6)2(32·48·512·66) type. The six-coordinated Co2+ ions in 3 are bridged by bpy and ptc ligands to give polymeric 1∞[Co(bpy)(H2O)4]2+ chains and 1∞[Co(ptc)(H2O)]1− chains, respectively, and the extensive hydrogen bonds are responsible for the construction of the 3D supramolecular architecture. Additionally, the ptc ligand exhibits two unprecedented coordination modes η5μ2 and η5μ3. The magnetic measurements of 1–3 show overall antiferromagnetic interactions between the metal ions.

Three new transition metal–organic coordination polymers [Zn(bpp)(C4H4O4)]·1.2H2O 1, [Cd(bpp)2(H2O)2](C4O4)·8H2O 2 and [Cd(bpp)2(C4O4)]·H2O 3 have been synthesized from the reaction of d10 block metal, dicarboxylic acid with 1,3-bis(4-pyridyl)-propane (bpp). Structural analysis reveal that the Zn atoms in 1 are bridged by the succinate anions to generate helical chains, which are interlinked by bpp ligands to a 3D framework with Sra (42 · 63 · 8) topology. The CdN4O2 octahedras in 2 are bridged by a pair of bpp ligands to form 1D repeated rhomboid chains, which are assembled into 2D layer via the hydrogen bonds. The six-coordinated Cd2+ ions in 3 are bridged by the acetylenedicarboxylato ligand to form 1D zigzag chains, which are interconnected by bpp ligands to construct 3D metal–organic framework with a (48 · 67) topology. The fluorescent spectra of 1–3 indicate intraligand fluorescence emission upon irradiation.Highlights►1 Represents a 3D frameworks with Sra topology. ►2 is a 1D repeated rhomboid chain. ►3 Exihibts a 3D (48 · 67) unprecedented topological network.

The title molecule crystallizes in the monoclinic space group P21/c, with a = 13.010(3), b = 5.562(1), c = 11.358(2) Å, β = 92.61(3)°. The 3-butene-1,2,3-tricarboxylic acid forms a hydrogen-bonded 2D (6,3) network that adopts a threefold 2D → 2D parallel interpenetrating sheets structure with a 63 topology, generated via the supramolecular assembly of the 3-butene-1,2,3-tricarboxylic acid nodes.

The ambient reactions of Zn(NO3)2·6H2O, 1,3-bis(4-pyridyl)-propane (bpp) and NaOH with benzoic acid, phenylacetic acid, phthalic acid, acetylenedicarboxylic acid afforded {Zn(bpp)(C6H5COO)2}·2H2O 1, Zn(bpp)(C6H5CH2COO)22, {Zn2(bpp)2[C6H4(COO)2]2}·2H2O 3 and Zn(bpp)(C4O4) 4. Except 2, which crystallizes in a centrosymmetric space group P21/n (no. 14), compounds 1, 3 and 4 crystallized in the acentric space groups Aba2 (no. 41), P21 (no. 4) and C2221 (no. 20), respectively. Compounds 1 and 2 feature 1D zigzag chains {[Zn(C6H5COO2](bpp)2/2} and {[Zn(C6H5CH2COO2](bpp)2/2}, respectively, generated from [Zn(C6H5COO)2] and [Zn(C6H5CH2COO)2] moieties bridged by bpp ligands. In 3, the phthalato bridged helical chains {Zn[C6H4(COO)2]2/2} are interlinked by TT- and TG-bpp ligands to form 3D MOF {Zn[C6H4(COO)2]2/2(TT-bpp)2/2(TG-bpp)2/2} with a (65·8) CdS topology. The acetylenedicarboxylato bridged helical chains {Zn[C2(COO)2]2/2} in 4 are interconnected by the bpp ligands to generate 3D MOF {Zn[C2(COO)2]2/2(TT-bpp)2/2} with a (66) diamond topology, and the formed crystal structure displays a four-fold interpenetration of the 3D MOF. Complexes 1, 3 and 4 exhibit significant ferroelectric behaviour (for 1 remnant polarization 2Pr = 3.97 × 10−4 μC cm−2, coercive field 2Ec =0.47 kV cm−1, saturation of the spontaneous polarization Ps = 2.63 × 10−3 μC cm−2; for 3 2Pr = 1.30 × 10−3 μC cm−2, 2Ec =1.02 kV cm−1, Ps = 5.42 × 10−3 μC cm−2; for 4 2Pr = 4.97 × 10−4 μC cm−2, 2Ec =0.46 kV cm−1, Ps = 2.08 × 10−3 μC cm−2). Additionally, 1 and 3 are verified to be SHG active. Furthermore, results about IR spectra, thermal analyses and fluorescence spectra were discussed.

Three new butane-1,2,3,4-tetracarboxylato bridged coordination polymers [Zn2(H2O)4(BTC)]·3H2O 1, [Cd2(H2O)4(BTC)]·2H2O 2 and [Y2(H2O)6(H2BTC)(BTC)]·5H2O 3 (H4BTC = butane-1,2,3,4-tetracarboxylic acid) were synthesized and characterized by IR spectroscopy, TG–DTA analyses, elemental analyses and single-crystal X-ray diffraction, and their fluorescence properties were also investigated. In 1, the trigonal pyramidally coordinated Zn atoms are brigded by both μ6η6 and μ6η8 centrosymmetric BTC4− anions into 2D layers, which are connected by the octahedrally coordinated Zn atoms to build up 3D (44·610·8)(44·62)2(44·68·82·10) topological framework with the lattice water molecules in cavities. In 2, the CdO7 pentagonal bipyramids and the CdO8 4,4′-bicapped triagonal antiprisms are edge-shared to generate the Cd2O13 bipolyhedra, which are further corner-shared into 1D metal-oxide chains. The resulting chains are interconnected by the μ6η8 BTC4− anion to form 2D (43)2(46·66·83) networks, which are assembled via interlayer hydrogen bonds into a 3D (411·611·86)(43)(49·6) topological supramolecular architecture with the lattice H2O molecules located in holes. The distorted 4,4′-bicapped triagonal antiprismatically coordinated Y atoms in 3 are interconnected μ4η4 H2BTC2− and μ4η6 BTC4− anions to from 2D (44·62) topological networks, which are held together via strong interlayer hydrogen bonds into a 3D fsc topological supramolecular architecture with the lattice water molecules residing in cavities.

Seven new glutaric acid complexes, Co(H2O)5L 1, Na2[CoL2] 2, Na2[L(H2L)4/2] 3, {[Co3(H2O)6L2](HL)2}·4H2O 4, {[Co3(H2O)6L2](HL)2}·10H2O 5, {[Co3(H2O)6L2]L2/2}·4H2O 6, and Na2{[Co3(H2O)2]L8/2]·6H2O 7 were obtained and characterized by single-crystal X-ray diffraction methods along with elemental analyses, IR spectroscopic and magnetic measurements (for 1 and 2). The [Co(H2O)5L] complex molecules in 1 are assembled into a three-dimensional supramolecular architecture based on intermolecular hydrogen bonds. Compound 2 consists of the Na+ cations and the necklace-like glutarato doubly bridged anionic chains, and 3 is composed of the Na+ cations and the anionic hydrogen bonded ladder-like anionic chains. The trinuclear {[Co3(H2O)6L2](HL)2} complex molecules with edge-shared linear trioctahedral [Co3(H2O)6L2]2+ cluster cores in 4 and 5 are hydrogen bonded into two-dimensional (2D) networks. The edge-shared linear trioctahedral [Co3(H2O)6L2]2+ cluster cores in 6 are bridged by glutarato ligands to generate one-dimensional (1D) chains, which are then assembled via interchain hydrogen bonds into 2D supramolecular networks. The corner-shared linear [Co3O16] trioctahedra in 7 are quaternate bridged by glutarato ligands to form 1D band-like anionic {[Co3(H2O)2]L8/2}2+ chains, which are assembled via interchain hydrogen bonds into 2D layers, and between them are sandwiched the Na+ cations. The magnetic behaviors of 1 and 2 obey the Curie−Weiss law with χm = C/(T − Θ) with the Curie constant C = 3.012(8) cm3·mol−1·K and the Weiss constant Θ = −9.4(7) K for 1, as well as C = 2.40(1) cm3·mol−1·K and Θ = −2.10(5) K for 2, indicating weak antiferromagnetic interactions between the Co(II) ions.

Two fumarato-bridged Co(II) coordination polymers Co(H2O)4L 1 and [Co3(H2O)4(OH)2L2]·2H2O 2 with H2LHOOCCH CHCOOH were prepared. Complex 1 consists of polymeric chains ∞1[Co(H2O)4(C4H2O4)2/2], which result from octahedrally coordinated Co atoms bridged by bis-monodentate fumarate anions and are assembled by interchain hydrogen bonds. Within 2, the edge-shared Co2O10 bi-octahedra are connected to the CoO6 octahedra to form 1D cobalt oxide chains and 3D open framework generated from the chains inter-linked by bis-bidentate fumarate anions displays rhombic tunnels, which are filled with the lattice H2O molecules. Thermal and magnetic behaviors of both the title coordination polymers are discussed. Crystal data: (1) monoclinic, P21/c, Z=4, a=7.493(1) Å, b=14.377(1) Å, c=7.708(1) Å, β=99.54(1)°, V=818.9(2) Å3, R1=0.0304, and wR2=0.0669 for 1487 observed reflections (I⩾2σ(I)) out of 1877 unique reflections; (2) monoclinic, P21/c, Z=2, a=6.618(1) Å, b=8.172(2) Å, c=15.578(3) Å, β=96.30(3)°, V=837.4(3) Å3, R1=0.0360 and wR2=0.0663 for 1442 observed reflections (I⩾2σ(I)) out of 1927 unique reflections.

The reactions of freshly prepared Cu(OH)2·xH2O and Cu(OH)2−2y(CO3)y·zH2O precipitates with imidazole and adipic acid in CH3OH/H2O at pH=5.4 yielded Cu(C3N2H4)2(HL)21 and Cu(C3N2H4)2L 2, respectively. Complex 1 consists of ribbon-like polymeric chains ∞1[Cu(C3N2H4)2(HL)4/2], in which the octahedrally coordinated Cu atoms are doubly bridged by bis-monodentate hydrogen adipato ligands. The interchain N–H⋯O hydrogen bonding interactions are responsible for supramolecular assembly of the polymeric chains into open 3D frameworks and two-fold interpenetration of the resulting open frameworks completes the crystal structure of 1. Within complex 2, the Cu atoms are penta-coordinated to form CuN2O3 square pyramids and condensed into Cu2N4O4 dimers, which are doubly bridged by twisted bis-monodentate adipato ligands into polymeric chains ∞1{[Cu(C3N2H4)2]2L4/2} with 4- and 18-membered rings progressing alternatively. The polymeric chains are assembled due to interchain N–H⋯O hydrogen bonding interactions. The thermal and magnetic behaviors of 1 and 2 is discussed.

Two succinato-pillared coordination polymers Mn5(OH)2L41 and Cd3(OH)2L22 were prepared by hydrothermal reactions of succinic acid (H2LHOOC(CH2)2COOH) and KOH with the corresponding metal chlorides at 180°C. Within 1, the adjacent MnO6 octahedra are edge shared to generate Mn5O22 pentamers, which are interconnected to form 2D manganese oxide layers stabilized by the intralayer gauche succinato groups within the aperture. The manganese oxide layers are pillared by the interlayer trans succinato groups to complete 3D framework. The magnetic behavior of 1 obeys Curie–Weiss law χm(T−Θ)=4.46(2) cm3 mol−1 K with the Weiss constant Θ=−67.3(3) K over the temperature range 5−300 K. Compound 2 contains CdO6 octahedra and edge-shared Cd2O10 bi-octahedra. The former CdO6 octahedra are each surrounded by four Cd2O10 bi-octahedra which in turn are each surrounded by four former CdO6 octahedra and four neighboring Cd2O10 bi-octahedra, thus resulting in the corrugated cadmium oxide layers. The formed 2D layers are pillared by trans succinato groups to constitute 3D coordination polymer. Additionally, thermal decomposition of both title coordination polymers upon heating in a flowing nitrogen atmosphere from room temperature to 800°C is discussed. Crystal data: (1) monoclinic, P21/c, Z=2, a=9.575(2) Å, b=9.611(2) Å, c=12.526(3) Å, β=97.04(2)°, V=1144.0(4) Å3, R1=0.0289 and wR2=0.0815 for 2411 observed reflections (I⩾2σ(I)) out of 2629 unique reflections; (2) orthorhombic, Pbca, Z=4, a=10.679(1) Å, b=6.873(1) Å, c=16.996(2) Å, V=1247.5(3) Å3, R1=0.0234 and wR2=0.0585 for 1213 observed reflections (I⩾2σ(I)) out of 1437 unique reflections.

Reactions of MoBr2 with NaBr and AgBr in sealed silica tubes at the temperature gradient 700/690 °C yield NaMo6Br13 and AgMo6Br13, respectively, at the low temperature zone. Both title compounds crystallize isostructurally in the triclinic space group (no. 2) with the cell dimensions: (1) a=9.299(1), b=9.443(2), c=14.480(3) Å, α=96.55(1)°, β=101.42(1)°, γ=115.32(1)°, V=1097.9(3) Å3, Z=2; (2) a=9.183(1), b=9.392(1), c=14.328(2) Å, α=95.85(1)°, β=102.04(1)°, γ=114.298(7)°, V=1076.8(3) Å3, Z=2. The crystal structures are composed of monovalent cations and the anionic chains. The zigzag anionic chains result from two crystallographically independent [Mo6Bri8]Bra4Bra–a2 cluster groups bridged by two opposite Bra-a atoms. Both [Mo6Bri8]Bra4Bra–a2 cluster groups and monovalent cations can be approximately viewed as being hexagonally close–packed in respective planes.Graphic

Four new Cu(II) complexes {[Cu4(bpy)4(OH)4(H2O)2]}(NO3)2(C7H5O2)2·6H2O 1, {[Cu4(bpy)4(OH)4(H2O)2]}(NO3)2(C5H6O4)·8H2O 2, {[Cu4(bpy)4(OH)4(H2O)2]}(C5H6O4)2·16H2O 3 and {[Cu6(bpy)6(OH)6(H2O)2]}(C8H7O2)6·12H2O 4 were synthesized (bpy = 2,2′-bipyridine, H2(C5H6O4) = glutaric acid, H(C7H5O2) = benzoic acid, H(C8H7O2) = phenyl acetic acid). The building units in 1–3 are the tetranuclear [Cu4(bpy)4(H2O)2(μ2-OH)2(μ3-OH)2]4+ complex cations, and in 4 the hexanuclear [Cu6(bpy)6(H2O)2(μ2-OH)2(μ3-OH)4]6+ complex cations, respectively. The tetra- and hexanuclear cluster cores [Cu4(μ2-OH)2(μ3-OH)2] and [Cu6(μ2-OH)2(μ3-OH)4] in the complex cations could be viewed as from step-like di- and trimerization of the well-known hydroxo-bridged dinuclear [Cu2(μ2-OH)2] entities via the out-of-plane Cu–O(H) bonds. The complex cations are supramolecularly assembled into (4,4) topological networks via intercationic π⋯π stacking interactions. The counteranions and lattice H2O molecules are sandwiched between the 2D cationic networks to form hydrogen-bonded networks in 1–3, while the phenyl acetate anions and the lattice H2O molecules generate 3D hydrogen-bonded anionic framework to interpenetrate with the (4,4) topological cationic networks with the hexanuclear complex cations in the channels. The ferromagnetic coupling between Cu(II) ions in the [Cu4(μ2-OH)2(μ3-OH)2] cores of 1–3 is significantly stronger via equatorial-equatorial OH− bridges than via equatorial-apical ones. The outer and the central [Cu2(OH)2] unit within the [Cu6(μ2-OH)2(μ3-OH)4] cluster cores in 4 exhibit weak ferromagnetic and antiferromagnetic interactions, respectively. Results about i.r. spectra, thermal and elemental analyses are presented.

It is well-known that the inner electric field formed between the counter electrode and the semiconductor surface has a substantial effect on the efficiencies of dye-sensitized solar cells (DSSCs). To reveal the function of the inner electric field for different types of porphyrin sensitizers in DSSCs, the properties of three types of porphyrin sensitizers (α, β, and center axial positions) under different electric fields were calculated by using density functional theory (DFT) and time dependent density functional theory (TD-DFT). The electronic structures and optical properties of these studied dyes in tetrahydrofuran (THF) solution were also investigated correspondingly. Key parameters of the short-circuit current density (Jsc) including light harvesting efficiency (LHE), electron injection driving force (ΔGinject) and intramolecular charge transfer (ICT) were detailedly discussed. The results show that the a-position type porphyrin sensitizer can be used as a potential sensitizer for DSSCs under an enhanced electric field. We expect that the present study would deepen the understanding of the function of an inner electric field and may be helpful in DSSC design in the future.