Synthesis and photo-/electro-catalytic properties of a 3D POMOF material based on an interpenetrated copper coordination polymer linked by in situ dual ligands and Dawson-type phosphotungstates

摘要

A novel 3D polyoxometalate metal organic framework (POMOF), [{(Cu6Cu10I)-Cu-II (H2O)(5)(pzc)(10)(pz)(6)}{P2W18O62}(2)]center dot 4H(2)O (1) (Hpzc = pyrazine-2-carboxylic acid, pz = pyrazine) has been hydrothermally synthesized and characterized by IR, TG, XRD, UV-vis and elemental analyses. In compound 1, the pzc and pz ligands are generated through in situ transformation from pyrazine-2,3-dicarboxylic acid (pzdc) to remove one or two CO2 molecules. The ligands with four coordination modes connect nine crystallo-graphically independent Cu atoms to form a super-big circle unit. Each ring unit is connected to the adjacent six rings via an edge-sharing way to form a 2-D Cu/pz/pzc MOF layer, which is further extended along two spatial directions by two kinds of insert modes to generate an interpenetrating and staggered 3-D metal organic network. The {P2W18} clusters as nine-node inorganic guest molecules are grafted on the Cu/pz/pzc framework forming a complex 3D POMOF with a new topology {4.6.8(3).10}(2) {4.6.8}(2) {4.6(2).8(2).10}(2){4.6(3).8(2)}(2){4.8(5)}(2){4(2).6(2).8(2)}(2){4(2).6(3).8}{4(3).6(7).8(13).10(10).12(3)}(2) {4}(6){6.8(2)}(2){6(2).8}(2) {6(4).8.10}6}(2){8}(4). Additionally, compound 1 exhibits good electrocatalytic activity for the reduction of H2O2 and effective photocatalytic degradation ability for three azo dyes under UV irradiation.