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

Abstract

Four mixed-ligand coordination networks, namely, {[Cu(pta)(1,4-bimb)_0.5(H₂O)_0.5]·H₂O}_n (1), {[Co(pta) (4,4′-bimbp) (H₂O)]·H₂O}_n (2),{[Cd(pta)(1,4-bidb)_0.5]·2H₂O}_n (3), and {[Zn(pta)(1,3-bimb)_0.5]·1.5H₂O}_n (4), were obtained under the solvothermal reactions in the presence of bis(imidazole) linkers (H₂pta = 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 Schläfli symbol of (4.8²)₂(4².8².10²)(8.10⁴.12). Complex 2 features a 2D (3,5)-connected (4².6⁷.8)(4².6)-3,5L2 sheet. Complexes 3 and 4 both exhibit a 3-fold 3D → 3D parallel entangled (3,4)-connected net with the Schläfli symbols of (4.6.8)(4.6².6³)-fsc-3,4-C2/c and (4.6.8)(4.6².8³)-3,4T1 for 3 and 4, respectively. Moreover, the solid state luminescence and the luminescent lifetime of 3 and 4 have been investigated.