Structural Transformations of Cobalt(II) Coordination Polymers Constructed from <i>N</i>,<i>N</i>′-Di-3-pyridyladipoamide and Tetracarboxylic Acids: Disentanglement upon Water Coordination
Yen-Fu Liu, Ji‐Hong Hu, Wei‐Te Lee, Xiang‐Kai Yang, Jhy‐Der Chen
Abstract
Hydrothermal reactions of N,N′-di-3-pyridyladipoamide (L) with 1,2,4,5-benzenetetracarboxylic acid (1,2,4,5-H2btec) in water without and with NaOH afforded [Co(L)(1,2,4,5-btec)0.5]n, 1, and [Co(L)(1,2,4,5-btec)0.5(H2O)2]n, 2, respectively, while immersion of 1 into water at room temperature gave {[Co(L)0.5(1,2,4,5-btec)0.5(H2O)4]·2H2O}n, 3, which have been structurally characterized. Complexes 1–3 display a 2-fold interpenetrated 3D framework, a unique 2D layer, and a 1D chain, respectively. While complexes 1 and 2 adopt the same point symbol of (4.64.8)2(42.62.82) for nets, they differ in the vertex symbols that are [4.86.6.6.6.6][4.4.62.62.82.82] and [4.810.6.6.6.6][4.4.62.62.810.810], respectively. Complexes 1–3 form a unique series of mixed-ligand coordination polymers that show 3-, 2-, and 1D structures, respectively, and differ in the bonding mode of the anionic polycarboxylate as well as the conformations of the neutral L ligand. Irreversible and temperature-dependent structural changes from 1 to 2 and 3 are observed, demonstrating the disentanglement of 1 upon water coordination at various temperatures, which can be ascribed to the variable bonding mode of 1,2,4,5-btec4– and the flexible nature of L.