New metal-organic frameworks based on 2,5-thiophenedicarboxylate and pyridine- or imidazole-based spacers: syntheses, topological structures, and properties

Solvothermal reactions of 2,5-thiophenedicarboxylate (H(2)tdc) and N-auxiliary ligands in the presence of cobalt(II), zinc(II) and cadmium(II) salts have given rise to seven new metal-organic frameworks, namely, [Co-2(tdc)(2)(bpp)(2)(H2O)center dot(H2O)](n) (bpp = 1,3-bis(4-pyridyl)propane) (1), [Cd(tdc)(bpp)(H2O)center dot(H2O)(2)](n) (2), [Zn2(tdc)(2)(bbi)(2)center dot(H2O)(2)](n) (bbi = 1,1'-(1,4-butanediyl)bis(imidazole)) (3), [Co-4(tdc)(3)(bimb)(4)(H2O)(5)center dot(tdc)center dot(DMF)center dot(H2O)(2)](n) (bimb = 4,4'-bis(1-imidazolyl)biphenyl) (4), [Zn-4(O)(tdc)(3)(bimb)(4)center dot(H2O)(5.25)center dot(CH3OH)](n) (5), [Cd-4(tdc)(4)(bimb)(6)center dot(H2O)(2)center dot(CH3OH)(2)center dot(DMF)(4)] (6) and [Co-2(tdc)(2)(tib)(2)center dot(H(2)tdc)center dot(DMF)(2)] (tib = 1,3,5-tris(1-imidazolyl)benzene) (7), which exhibit structural diversity. Compounds 1-3 display 3D 2-fold interpenetrating 8-connected tsi net, 2D 4-connected sql net, and 3D 5-fold interpenetrating 4-connected dia net, respectively; while compound 4 features an extremely rare 3D 7-connected hxg-d cationic net and compound 5 adopts a 3D trinodal (4,4,6)-connected net with a new topology structure. For compounds 6 and 7, the topology in the structures were determined as 3D 3-fold interpenetrating 5-connected bnn net and 3D 2-fold interpenetrating binodal (3,5)-connected net, respectively. In the solid state, complexes 1, 4 and 5 exhibit nonlinear optical properties, and complex 5 has also been evaluated as a promising visible-light-driven photocatalyst for degradation of organic pollutants. The magnetic investigation of complexes 1 and 4 shows that there exists spin-canted antiferromagnetism for 1, whereas strong antiferromagnetic interaction and/or the depopulation of the higher energy Kramers doublets of the Co(II) centers are dominant in 4.