Synthesis, structures, electrochemistry and electrocatalysis of two novel copper(II) complexes constructed with aromatic polycarboxylates and dipyrido[3,2-d:2′,3′-f]quinoxaline

Two novel coordination polymers [Cu3(1,3-BDC)4(Dpq)2] (1) and [Cu2(BTC)(OH)(Dpq)2] · H2O (2), have been hydrothermally synthesized by self-assembly of aromatic polycarboxylate ligands 1,3-H2BDC (1,3-H2BDC = 1,3-benzenedicarboxylate) or H3BTC (H3BTC = 1,3,5-benzenetricarboxylate), chelating ligand Dpq (Dpq = dipyrido[3,2-d:2′,3′-f]quinoxaline), and copper chloride. X-ray diffraction analysis reveals that each trinuclear CuII cluster is bridged by two coordination modes of 1,3-BDC ligands to form one-dimensional (1-D) chain structure in complex 1. Complex 2 possesses a two-dimensional (2-D) layer network composed of dinuclear [Cu2(OH)(Dpq)2] unit and bridging ligand BTC. The adjacent chains for 1 or the adjacent layers for 2 are further linked by π–π stacking interactions to form the three-dimensional (3-D) supramolecular frameworks. Moreover, the electrochemical properties of the two copper(II) complexes bulk-modified carbon paste electrodes (Cu-CPEs: 1-CPE and 2-CPE) have been studied, and the results indicate that both Cu-CPEs give one-electron quasi-reversible redox waves in potential range of 600 to −400 mV due to the metal copper ion Cu(II)/Cu(I). The Cu-CPEs have good electrocatalytic activities toward the reduction of nitrite and bromate in 0.1 M pH 2 phosphates buffer solution, and have 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.

Hydrothermal synthesis, crystal structures, electrochemical and electrocatalytical properties of two novel coordination polymers constructed with mixed ligands of aromatic polycarboxylate (1,3-BDC or BTC) and dipyrido[3,2-d:2′,3′-f]quinoxaline (Dpq): [Cu3(1,3-BDC)4(Dpq)2] (1) and [Cu2(BTC)(OH)(Dpq)2] · H2O (2).Two novel coordination polymers [Cu3(1,3-BDC)4(Dpq)2] (1) and [Cu2(BTC)(OH)(Dpq)2] · H2O (2) have been obtained from hydrothermal reactions. Two copper complexes exhibit one-dimensional chain for 1 and two-dimensional layer structure for 2, respectively. And the adjacent chains in 1 and the adjacent layers in 2 are further linked by π–π stacking interactions to form three-dimensional supramolecular framework. Moreover, the copper(II) complexes bulk-modified carbon paste electrodes (Cu-CPEs: 1-CPE and 2-CPE) have good electrocatalytic activities toward the reduction of nitrite and bromate in 0.1 M pH 2 phosphates buffer solution.Figure optionsDownload as PowerPoint slide