Temperature-Dependant Assemblies of Cu(II) Coordination Polymers and In Situ Ligand Reaction Based on 2,2′-Bipyridine-3,3′,6,6′-Tetracarboxylic acid

Three Cu(II) coordination polymers (CPs), namely, Cu(hbpdc) 0.5 (H 2 O) 2 ( 1 ), [Cu 2 (hbpdc)(H 2 O) 2 ] n ( 2 ), {[Cu 3 (hbpdc)(OH) 2 (H 2 O)]·H 2 O} n ( 3 ) (H 4 hbpdc = 3,3′-dihydroxy-2,2′-bipyridine-6,6′-dicarboxylic acid) have been obtained based on 2,2′-bipyridine-3,3′,6,6′-tetracarboxylic acid ligand (H 4 bptc) under hydro(solvo)thermal condition, and interestingly, the H 4 hbpdc ligand is in situ generated from H 4 bptc ligand during the synthetic process owing to the high temperature and pressure of the reaction system. Among the three complexes, 1 displays a discrete dinuclear copper building block, 2 possesses a 2D sheet, while 3 exhibits a porous 3D structure, and there exist Cu(II) centers in 3 showing an unprecedented one-capped trigonal prismatic coordination geometry. Structural comparisons indicate that the high reaction temperature is crucial factor for the in situ ligand reaction, and the solvent system and pH value play important roles in the coordination modes of H 4 nbtc ligand to produce various dimensional coordination polymers.