Syntheses, structures, topologies, and luminescence properties of four coordination polymers based on bifunctional 6-(4-pyridyl)-terephthalic acid and bis(imidazole) bridging linkers

Four mixed-ligand coordination networks, namely, {[Cu(pta)(1,4-bimb)(0.5)(H2O)(0.5)]center dot H2O}(n) (1), {[Co(pta) (4,4'-bimbp) (H2O)]center dot H2O}(n) (2),{[Cd(pta)(1,4-bidb)(0.5)]center dot 2H(2)O}(n) (3), and {[Zn(pta)(1,3-bimb)(0.5)]center dot 1.5H(2)O}(n) (4), were obtained under the solvothermal reactions in the presence of bis(imidazole) linkers (H(2)pta = 6-(4-pyridyl)-terephthalic acid, 1,4-bidb = 1,4-bis(imidazol-1-yl)-2,5-dimethyl benzene, 1,3-bimb = 1,3-bis(imidazol-1-ylmethyl)benzene, 1,4-bimb = 1,4-bis(imidazol-1-ylmethyl)benzene, and 4,4'-bimbp = 4,4'-bis(imidazol-1-ylmethyl)biphenyl). Their structures were 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. Complex 1 displays a novel (3,4,4)-connected topology with the Schlafli symbol of (4.8(2))(2)(4(2).8(2).10(2))(8.10(4).12). Complex 2 features a 2D (3,5)-connected (4(2).6(7).8)(4(2).6)-3,5L2 sheet. Complexes 3 and 4 both exhibit a 3-fold 3D -> 3D parallel entangled (3,4)-connected net with the Schlafli symbols of (4.6.8)(4.6(2).6(3))-fsc-3,4-C2/c and (4.6.8)(4.6(2).8(3))-3,4T1 for 3 and 4, respectively. Moreover, the solid state luminescence and the luminescent lifetime of 3 and 4 have been investigated.