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}_<i>n</i> (<b>1</b>), [Mn₂(μ₆-ao₂btc)­(μ-obix)₂]_<i>n</i> (<b>2</b>), [Cd₂(μ₆-ao₂btc)­(μ-obix)₂]_<i>n</i> (<b>3</b>), [Zn₂(μ₄-aobtc)­(μ-dib)₂]_<i>n</i> (<b>4</b>), and {[Zn₂(μ₄-ao₂btc)­(μ-dmib)₂]­·2H₂O}_<i>n</i> (<b>5</b>) (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 <b>1</b>–<b>5</b> displayed diverse structures depending on flexible, semiflexible, and rigid bis­(imidazole) linkers. Complex <b>1</b> has a three-dimensional (3D) structure with the rare sqc27 topology. Complexes <b>2</b> and <b>3</b> are isostructural with 3,6L19 topology. Complexes <b>4</b> and <b>5</b> 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 <b>1</b> and <b>4</b>, respectively. Moreover, thermal and photoluminescence properties of the complexes were discussed in detail