Three bulky conjugated 4-(2,6-di(pyrazin-2-yl)pyridin-4-yl)benzoate-based chains exhibiting dual photocatalytic and electrocatalytic performances

Abstract

Three bulky conjugated 4-(2,6-di(pyrazin-2-yl)pyridin-4-yl)benzoate (L)-based coordination polymers (CPs), {[Cu(L)Cl]·2.25H2O}n (1), {[Cu(H2O)(L)](NO3)·H2O}n (2) and {[Zn(H2O)(L)(NO3)][Zn(H2O)2(L)](NO3)H2O}n (3), were solvothermally synthesized by varying transition metal ions and pH values of the reactant mixture. Their crystal structures, band gaps and catalytic performances for photodegradation of organic dyes and electrocatalytic reduction of hydrogen peroxide were fully investigated. Single-crystal structural determinations reveal that both 1 and 2 are bent one-dimensional (1D) chains constructed from ditopic L− connectors and square pyramidal CuII ions in slightly different coordination environments. By contrast, complex 3 consists of two hydrogen-bonding 1D chains with hexacoordinate ZnII octahedra extended by L− linkers. Due to the more suitable band gap and the unsaturated coordination site of the CuII center, the three CPs exhibit varied photodegradation activity of Rhodamine B and Methylene Blue with the degradation rates of 91.2% and 91.9% for 1, 84.9% and 86.9% for 2 as well as 30.6% and 42.7% for 3. Additionally, 1 and 2 also display good electrocatalytic activity towards the reduction of hydrogen peroxide.