Syntheses, Structures, and Photoluminescent 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)(H 2 O)] ( 1 ), [Cd(L) 2 Na 2 ]·H 2 O ( 2 ), [Cd(L)(phen)] ( 3 ), [Cd(L)(phen)]·2H 2 O ( 4 ), [Cd 2 (L) 2 (biim-2)]·H 2 O ( 5 ), [Cd(L)(biim-4)]·2H 2 O ( 6 ), [Co(L)(biim-4)]·H 2 O ( 7 ), [Cd(L)(btp)] ( 8 ), [Cd(L)(btb)] ( 9 ), [Cd(HL)(bth) 0.5 (H 2 O)]·H 2 O ( 10 ), [Co(HL)(btb) 0.5 ]·H 2 O ( 11 ), and [Cd(L)(btbp) 1.5 ]·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 H 2 L = (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 (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 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 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.