Syntheses, crystal structures and UV-visible absorption properties of five metal-organic frameworks constructed from terphenyl-2,5,2',5'-tetracarboxylic acid and bis(imidazole) bridging ligands

摘要

The solvothermal reactions of terphenyl-2,5,2',5'-tetracarboxylic acid (H4tptc) and transition metal cations(NiII, MnII) afford five novel coordination polymers (CPs) in the presence of four bis(imidazole) bridging ligands (1,3-bimb = 1,3-bis(imidazol-1-ylmethyl)benzene, 1,4-bmib = 1,4-bis(2-methylimidazol-1-ylmethyl)benzene, 4,4'-bibp = 4,4'-bis(imidazol-1-yl)biphenyl, 4,4'-bimbp = 4,4'-bis(imidazol-1-ylmethyl)-biphenyl), namely, M(tptc)_(0.5)(1,3-bimb)(H_2O)n (M = Ni for 1, Mn for 2), {Ni(tptc)_(0.5)(1,4-bmib)˙0.25H_2O}n(3), {Ni(tptc)_(0.5)(4,4'-bibp)_2(H_2O)˙2H_2O}n (4) and {Ni(tptc)_(0.5)(4,4'-bimbp)_(1.5(H_2O)?H_2O}n (5). Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD), and thermogravimetric (TG) analyses. Complexes 1 and 2 are isomorphous and exhibit a 3D (3,4)-connected tfi framework with the point Schl?fli symbol of (4?6~2)(4?6~6?8~3). Complex 3 shows an unprecedented 3D (4,4)-connected framework with the point Schl?fli symbol of (4?6~4?8~2)_2(4~2?8~4). Complex 4 displays a novel 2D self-catenating 5-connected network with the Schl?fli symbol of (4~6?6~4) based on three interpenetrating 44-sql subnets. Complex 5 features a 2D 3-connected 63-hcb network built from interesting chains with loops. To the best of our knowledge, the 3D (4,4)-connected (4?6~4?8~2)_2(4~2?8~4) host-framework of 3 and 2D selfcatenating 5-connected (4~6?6~4) network of 4 have never been documented to date. Moreover, the UV-Visible absorption spectra of complexes 1-5 have been investigated.