A novel copper(II) complex constructed with mixed ligands of biphenyl-4,4′-dicarboxylic acid (H2bpdc) and dipyrido[3,2-d:2′,3′-f]quinoxaline (Dpq): Synthesis, structure, electrochemistry and electrocatalysis

A novel metal–organic framework [Cu2(bpdc)2(Dpq)2(H2O)]·H2O (1) has been obtained from hydrothermal reaction of copper chloride with the mixed ligands [biphenyl-4,4′-dicarboxylic acid (H2bpdc) and dipyrido[3,2-d:2′,3′-f]quinoxaline (Dpq)], and structurally characterized by elemental analysis, IR, TG and single-crystal X-ray diffraction analysis. The unique feature is that there simultaneously exist two kinds of one-dimensional (1-D) zigzag polymeric chains in complex 1. Moreover, the 1-D polymeric chains are ultimately packed into a three-dimensional (3-D) supramolecular framework through two different hydrogen bonding interactions. The adjacent different chains are linked by C–H⋯O hydrogen bonding interactions, and the same kind chains are further connected through C–H⋯π stacking interactions. Additionally, the complex 1 was used as solid bulk-modifier to fabricate renewable carbon paste electrode (Cu-CPE) by the direct mixing method. The electrochemical behavior and electrocatalysis of Cu-CPE have been studied in detail. The results indicate that Cu-CPE give one-electron quasi-reversible redox waves in potential range of 400 to −300 mV due to the metal copper ion Cu(II)/Cu(I). The Cu-CPE showed good electrocatalytic activity toward the reduction of the bromate, nitrite and hydrogen peroxide. The electrocatalytic reduction peak currents of KBrO3, KNO2 and H2O2 showed a linear dependence on their concentrations. All of the results revealed that the Cu-CPE had a good reproducibility, remarkable long-term stability and especially good surface renewability by simple mechanical polishing in the event of surface fouling, which is important for practical application.

Complex [Cu2(bpdc)2(Dpq)2(H2O)]·H2O (1) possesses two kinds of one-dimensional (1-D) zigzag polymeric chains, and the chains are further linked by C–H⋯O and C–H⋯π hydrogen bonding interactions to form a three-dimensional (3-D) supramolecular framework. Moreover, the copper(II) complex bulk-modified carbon paste electrode (Cu-CPE) has good electrocatalytic activities toward the reduction of nitrite, bromate and hydrogen peroxide.Figure optionsDownload as PowerPoint slide