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

Five new mixed-ligand coordination polymers, formulated as {[Cd2(μ6-ao2btc)­(μ-1,4-bmeib)­(H2O)2]­·2H2O}n (1), [Mn2(μ6-ao2btc)­(μ-obix)2]n (2), [Cd2(μ6-ao2btc)­(μ-obix)2]n (3), [Zn2(μ4-aobtc)­(μ-dib)2]n (4), and {[Zn2(μ4-ao2btc)­(μ-dmib)2]­·2H2O}n (5) (aobtc and ao2btc = 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 62·84) and bbf topology (the point symbol of {64.82}­{66}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.