Coordination Polymers Assembled From 3,3 ',5,5 '-Azobenzenetetracarboxylic Acid and Different Bis(imidazole) Ligands with Varying Flexibility

Abstract

Five new mixed-ligand coordination polymers, formulated as {[Cd-2(mu(6)-ao(2)btc)(mu-1,4-bmeib)(H2O)(2)].2H(2)O}(n) (1), [Mn-2(mu(6)-ao(2)btc)(mu-obix)(2)](n) (2), [Cd-2(mu(6)-ao(2)btc)(mu-obix)(2)](n) (3), [Zn-2(mu(4)-aobtc)(mu-dib)(2)](n) (4), and {[Zn-2(mu(4)-ao(2)btc)(mu-dmib)(2)].2H(2)O}(n) (5) (aobtc and ao(2)btc = mono- and dioxygenated forms of 3,3',5,5'-azobenzenetetracarboxylate, 1,4-bmeib = 1,4-bis(2-methylimidazol-1yl)butane, obix = 1,2-bis(imidazol-1ylmethyl)benzene, dib = 1,4-bis(imidazol-1yl)benzene, and dmib = 1,4-bis(imidazol-1yl)-2,5-dimethylbenzene) have been synthesized using different bis(imidazole) ligands and characterized by elemental analyses, IR spectra, single-crystal X-ray diffraction, powder X-ray diffraction, and thermal analyses (TG/DTA). Complexes 1-5 displayed diverse structures depending on flexible, semiflexible, and rigid bis(imidazole) linkers. Complex 1 has a three-dimensional (3D) structure with the rare sqc27 topology. Complexes 2 and 3 are isostructural with 3,6L19 topology. Complexes 4 and 5 display 2-fold interpenetrated 3D structures with new topology (the point symbol of 6(2).8(4)) and bbf topology (the point symbol of {6(4).8(2)}{6(6)}(2)), respectively. Ao2btc and aobtc ligands show new coordination modes in 1 and 4, respectively. Moreover, thermal and photoluminescence properties of the complexes were discussed in detail.