Two copper(II) metal-organic networks derived from bis-pyridyl-bis-amide ligands and aromatic polycarboxylates: a 2-D layered structure and a 4-connected trinodal 3-D topology

Two metalorganic coordination polymers, [Cu3(4-bpcb)2(1,2,4-btc)2(H2O)2] (1) and [Cu3(3-bpcb)3(btec)1.5] (2), have been synthesized from hydrothermal reaction of copper chloride with mixed ligands [4-bpcb=N,N-bis(4-pyridinecarboxamide)-1,4-benzene, 3-bpcb=N,N-bis(3-pyridinecarboxamide)-1,4-benzene, 1,2,4-H3btc=1,2,4-benzenetricarboxylic acid, and H4btec=1,2,4,5-benzenetetracarboxylic acid]. X-ray diffraction analysis reveals that 1 exhibits a 2-D layer structure and 2 possesses a three-dimensional (3-D) network. In 1 and 2, CuII ions are connected by bridging 1,2,4-btc or btec to form 2-D polymeric layers. Cu-1,2,4-btc layer does not propagate into a 3-D coordination framework in 1 due to 4-bpcb showing monodentate coordination (via ligation of only one pyridyl nitrogen). In 2, Cu-btec 2-D layers are further extended into a 3-D network with (64.82)3 topology by 3-bpcb ligand in 2-bridging coordination (via ligation of two pyridyl nitrogens). The different structures of the two complexes illustrate the influence of different polycarboxylates and N-donor positions of organic ligands on the formation of such coordination architectures. Moreover, the thermal properties and electrochemical properties of the copper complexes bulk-modified carbon paste electrodes have been studied.