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

Abstract

Twelve new metal–organic frameworks (MOFs), namely, [Cd(L)(H2O)] (1), [Cd(L)2Na2]·H2O (2), [Cd(L)(phen)] (3), [Cd(L)(phen)]·2H2O (4), [Cd2(L)2(biim-2)]·H2O (5), [Cd(L)(biim-4)]·2H2O (6), [Co(L)(biim-4)]·H2O (7), [Cd(L)(btp)] (8), [Cd(L)(btb)] (9), [Cd(HL)(bth)0.5(H2O)]·H2O (10), [Co(HL)(btb)0.5]·H2O (11), and [Cd(L)(btbp)1.5]·4H2O (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 36·46·53 topology. Compounds 3 and 4 exhibit similar one-dimensional (1D) double chains, which are further extended into 2D supramolecular sheets and three-dimensional (3D) supramolecular frameworks through π–π interactions between pyridyl rings and phenyl rings, respectively. Compound 5 furnishes a 1D double chain, which is further extended into a 2D supramolecular layer via two kinds of π–π interactions. Compounds 6 and 7 are isostructural and display the same 2D undulated sheets with 44·62 topology. Compound 8 possesses a 2D sheet structure. Compound 9 displays 3D (3,4)-connected frameworks with (4·102)(4·103·122) topology. Compounds 10 and 11 possess similar 1D infinite chains, which are further linked via π–π 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.