Syntheses, Structures, and Photo luminescent Properties of 12 New Metal-Organic Frameworks Constructed by a Flexible Dicarboxylate and Various N-Donor Ligands

Twelve new metal organic frameworks (MOFs), namely, [Cd(L)(H2O)] (1), [Cd(L)(2)Na-2]center dot H2O (2), [Cd(L)(Phen)] (3), [Cd(L)(phen)]center dot 2H(2)O (4), [Cd-2(L)(2)(biim-2)]center dot H2O (5), [Cd(L)-(biim-4)]center dot 2H(2)O (6), [Co(L)(biim-4)]center dot H2O (7), [Cd(L)(btP)] (8), [Cd(L)(btb)] (9), [Cd(HL)(bth)(0.5)(H2O)]center dot H2O (10), [Co(HL)-(btb)(0.5)]center dot H2O (11), and [Cd(L)(btbp)(1.5)]center dot 4H(2)O (12), where phen = 1,10-phenathroline, biim-2 = 1,2-bis(imidazol-1'-yl)ethane, biim-4 = 1,1'-(1,4-butanediyl)bis(imidazole), btp = 1,3-bis(1,2,4-triazol-1-yl)propane, btb = 1,4-bis(1,2,4-triazol-1-yl)butane, bth = 1,6-bis(1,2,4-triazol-1-yl)hexane, btbp = 4,4'-bis(1,2,4-triazol-1-ylmethyl)biphenyl, and H2L = (3-carboxyl-phenyl)-(4-(2'-carboxyl-phenyl)-benzyl) ether, have been synthesized under hydrothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD), and thermogravimetric (TG) analyses. Compound 1 features a two-dimensional (2D) layer, which is further stabilized by hydrogen bonds between the coordinated water molecules and adjacent carboxylate oxygen atoms. Compound 2 shows a 2D double layer with 3(6).4(6).5(3) topology. Compounds 3 and 4 exhibit similar one-dimensional (ID) double chains, which are further extended into 2D supramolecular sheets and three-dimensional (3D) supramolecular frameworks through pi-pi interactions between pyridyl rings and phenyl rings, respectively. Compound 5 furnishes a ID double chain, which is further extended into a 2D supramolecular layer via two kinds of pi-pi interactions. Compounds 6 and 7 are isostructural and display the same 2D undulated sheets with 4(4).6(2) topology. Compound 8 possesses a 2D sheet structure. Compound 9 displays 3D (3,4)connected frameworks with (4.10(2))(4.10(3).12(2)) topology. Compounds 10 and 1.1 possess similar ID infinite chains, which are further linked via pi-pi interactions to generate 2D supramolecular layers. Compound 12 possesses a 2D double layer, which is further extended into a 3D supramolecular architecture through hydrogen-bonding interactions. The structural and topological differences of the 12 compounds indicate that the L anion and N-donor ligands play important roles in the formation of the final framework structures. The thermal behaviors of compounds 1, 3-4, 8-10, and 12 and luminescent properties of 1-6, 8-10, and 12 have also been investigated in detail.