Preparation and characterization of two new metal–organic coordination polymers with 3,3′-azodibenzoic acid under <i>N</i>-donor auxiliary chelating ligand intervention

<div><p>Reactions of 3,3′-azodibenzoic acid (H₂azdc) with Mn(II) and Cd(II) in the presence of 1,10-phenanthroline (phen) yield two new metal–organic coordination polymers, {[Mn(azdc)(phen)(DMF)(H₂O)]}_n (<b>1</b>) and {[Cd(azdc)(phen)]}_n (<b>2</b>), which display 1-D azdc-bridged coordination arrays with different topology. <b>1</b> was synthesized under ambient conditions and exhibits a <i>zigzag</i> chain structure, further extending into a 2-D supramolecular double layer through C–H<i>π</i> and C<i>–</i>HO hydrogen bonds. Solvothermally <b>2</b> was obtained and shows a double-chain structure. Adjacent double chains are linked by C–HN hydrogen bonds to give a 2-D supramolecular wavy double layer. Distinct extended 3-D supramolecular network architectures are further constructed with weak secondary interactions, especially aromatic stacking and hydrogen bonding as supramolecular driving forces. The coordination modes of azdc²⁻ and crystalline architectures of the complexes depend on the central metal ions. The desolvation–resolvation behavior of <b>1</b> has been explored. Thermal stabilities of <b>1</b> and <b>2</b> have been studied. Solid-state fluorescence of <b>2</b> has been investigated.</p>