Two new 2D copper(II) complexes constructed from a flexible bis-pyridyl-bis-amide ligand and two aromatic tricarboxylates: syntheses, crystal structures, fluorescence, and electrochemical properties

Abstract

Two new 2D metal-organic complexes, namely [Cu(3-dpyb)(1,2,4-HBTC)(H2O)]·H2O (1) and [Cu3(3-dpyb)3(SIP)2(H2O)8]·6H2O (2) [3-dpyb = N,N’-bis(3-pyridinecarboxamide)-1,4-butane, 1,2,4-H3BTC = 1,2,4-benzenetricarboxylic acid, H3SIP = 5-sulfoisophthalic acid], have been hydrothermally synthesized and structurally characterized by elemental analyses, IR, TG, and single crystal X-ray diffraction analyses. Single crystal X-ray analyses reveal that the two Cu(II) complexes show different 2D coordination networks, the 4-connected (44·62) topology for complex 1 and the (4·62)2(42·62·82) topology for complex 2. In the 2D layers of complexes 1 and 2, the 3-dpyb ligands adopt a typical μ 2-bridging mode (via ligation of two pyridyl nitrogen atoms), while 1,2,4-HBTC and SIP serve as a linear spacer and a ‘V’-like linker, respectively, to connect the adjacent Cu(II) centers. The adjacent 2D layers are extended to 3D supramolecular networks via hydrogen-bonding interactions. The fluorescence properties of both complexes and electrochemical properties of complex 2 have also been investigated. The complex 2 bulk-modified carbon paste electrode (2-CPE) displayed a one-electron redox wave in potential range of 600–200 mV in 1 M H2SO4 aqueous solution, and 2-CPE showed good electrocatalytic activity toward the reduction of nitrite.