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A series of structurally diverse metal–organic frameworks (MOFs), [Co4(TPOM)2(L1)4(H2O)4]·H2O (1), [Ni2(TPOM)(L2)2(H2O)2]·2H2O (2), [Co2(TPOM)(L2)2(H2O)2]·H2O (3), [Cu4(TPOM)2(L3)4]·3H2O (4), [Co2(TPOM)0.5(L4)] (5), and [Cd(TPOM)(L3)3]·7H2O (6), where TPOM = tetrakis(4-pyridyloxymethylene)methane, H2L1 = 1,3-benzenedicarboxylic acid, H2L2 = 5-hydroxyisophthalic acid, H3L3 = 1,3,5-benzenetricarboxylic acid, and H4L4 = 1,2,4,5-benzenetetracarboxylic acid, have been hydrothermally synthesized. These complexes were structurally characterized by X-ray diffraction analyses and further characterized by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD), and thermogravimetric (TG) analyses. Compound 1shows a 3D 4-connected framework with a rare (84·62) topology. Compounds 2and 3are isostructural and display 3D 2-fold interpenetrating frameworks with (64·82)(66)2topologies. Compound 4exhibits a 2-fold interpenetrating structure with a scarce trinodal (3,4,5)-connected (4·62)(4·69)66topology. Compound 5possesses a 3D 4-connected net with the TPOM ligands located in the 3D channels. Compound 6features 2D square layers (sql). The free TPOM ligands and L3 anions form discrete fragments through hydrogen bonds and π–π interactions. Interestingly, the fragments penetrate the 2D networks above and below to yield a unique 2D → 3D polythreading framework. The structural differences among such compounds show the effects of the carboxylates and central metals on the complex structures. The UV–vis absorption spectra, optical energy gap, and luminescent properties were also investigated for the compounds. [ABSTRACT FROM AUTHOR]

Thirteen new metal–organic frameworks (MOFs), namely, [Zn2(L1)2(biim-4)(H2O)] (1), [Cd(HL1)2(biim-4)] (2), [Cd(HL2)2(biim-4)] (3), [Cd(HL3)2(biim-4)] (4), [Zn2(L4)2(biim-4)(H2O)] (5), [Cd(HL4)2(biim-4)] (6), [Zn2(L5)2(biim-4)(H2O)] (7), [Cd(HL5)2(biim-4)1.5]·H2O (8), [Zn2(L6)2(biim-4)(H2O)] (9), [Cd(HL6)2(biim-4)] (10), [Zn2(L7)2(biim-4)2]·H2O (11), [Cd2(L7)2(biim-4)2(H2O)]·H2O (12), and [Zn(HL8)(biim-4)]·0.5H2O (13), where H2L1 = salicylic acid, H2L2 = 3-methylsalicylic acid, H2L3 = 4-methylsalicylic acid, H2L4 = 4-chlorosalicylic acid, H2L5 = 5-chlorosalicylic acid, H2L6 = 5-bromosalicylic acid, H2L7 = 5-nitrosalicylic acid, H3L8 = 5-sulfosalicylic acid, and biim-4 = 1,1′-(1,4-butanediyl)bis(imidazole), have been synthesized under hydrothermal conditions. Compounds 1and 5are isomorphous, and show the same 3-connected 103-thsnet. Compound 2possesses a meso-helical chain structure. Compound 3shows a zero-dimensional (0D) dimeric molecular structure, which is linked by π–π interactions into a two-dimensional (2D) supramolecular assembly. Compounds 4and 6exhibit similar one-dimensional (1D) chains, which are extended into different 2D supramolecular layers via C–H···O and C–H···Cl hydrogen-bonding interactions, respectively. Compound 9is isomorphous with 7and displays a typical 3D diamond framework. Compound 8shows an unusual 2D → 3D polythreading array. Compound 10furnishes a 2D supramolecular (44)-sqlnetwork formed by C–H···Br hydrogen-bonding interactions. Compounds 11and 12exhibit binodal (4,4)-connected 3D frameworks with (4.53.72)(4.52.83) and (42.62.82)(42.6.82.10) topologies, respectively. Compound 13has a 3D 4-fold interpenetrating diamond framework. The TGA and luminescent properties of 1–13have also been investigated in detail. [ABSTRACT FROM AUTHOR]

Four octamolybdate hybrid materials based on a new flexible multidentate ligand, namely, H4L(γ-Mo8O26)·2H2O (1), [Cu(H2L)(β-Mo8O26)(H2O)2]·3H2O (2), [Cu(H2L)(γ-Mo8O26)]·3H2O (3), and Cu(HL)2(β-Mo8O26) (4), where Lis 1,1′-(1,4-butanediyl)bis[2-(4-pyridyl)benzimidazole], have been synthesized at different pH values under hydrothermal conditions. Compound 1, which is hydrothermally prepared at pH ≈ 1, exhibits a rare one-dimensional (1D) molybdenum oxide chain. Compounds 2and 3are hydrothermally obtained at pH ≈ 2.5. In 2, CuIIcations are bridged by H2L2阨᪝ and (β-Mo8O26)4–anions to form an interesting two-dimensional (2D) layer. In 3, the H2L2阨᪝ and (γ-Mo8O26)4–clusters bridge adjacent CuIIcations to form a 3D framwork. When the pH value is adjusted to 3.5, compound 4is obtained. Because the HL熫抢 acts as a monodentate ligand, compound 4only exhibits a 1D chain structure. The structural diversities of 1–4reveal that the pH value of the reaction system plays a crucial role in the assembly of POM-based metal–organic frameworks (MOFs). In addition, the electrochemical property of compound 4has also been investigated in 1 M H2SO4aqueous solution. [ABSTRACT FROM AUTHOR]