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

The solvothermal reactions of terphenyl- 2,5,2',5'-tetracarboxylic acid (H(4)tptc) and transition metal cations (Ni-II, Mn-II) 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)(H2O)](n) (M = Ni for 1, Mn for 2), {[Ni(tptc)(0.5)(1,4-bmib)] 0.25H(2)O}(n) (3), {[Ni( tptc)(0.5)(4,4'-bibp)(2)(H2O)].2H(2)O}(n) (4) and {[Ni(tptc)(0.5)(4,4'-bimbp)(1.5)(H2O)].H2O}(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 Schlafli symbol of (4.6(2))(4.6(6).8(3)). Complex 3 shows an unprecedented 3D (4,4)-connected framework with the point Schlafli 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 Schlafli symbol of (4(6).6(4)) based on three interpenetrating 44-sql subnets. Complex 5 features a 2D 3-connected 6(3)=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.