Four octamolybdate- and Keggin-based compounds constructed by flexible bis(triazole) ligands with different spacers

Abstract

By using two kinds of flexible bis(triazole) ligands 1,3-bis(1,2,4-triazol-1-y1)propane (btp) and 1,6-bis(1,2,4-triazol-1-y1)hexane (btx), four compounds based on octamolybdate and Keggin anions were obtained, respectively, under hydrothermal conditions, namely [Cu(btp)2(H2O)(α-Mo8O26)1/2]·H2O (1), [Cu2(btx)4(β-Mo8O26)] (2), [Ag3(btp)2(PW12O40)] (3) and [Cd(btx)3(SiW12O40)]·H2btx (4). These compounds were structurally characterized by physico-chemical and spectroscopic methods. In compound 1, there is a metal–organic layer containing square tetra-nuclear cycles. Two layers cover [Mo8O26]4− anions to form a new layer. Adjacent new layers penetrate to build a three-dimensional (3D) framework. Compound 2 contains a rhomboid tetra-nuclear cycle to surround a Mo1-containing anion. These cycles are connected by btx ligands to form a two-dimensional (2D) layer. Adjacent layers are connected by Mo5-containing anions, and a 3D structure is constructed. Compound 3 contains bi-nuclear cycles which are further linked by anions and Ag2 atoms to form a 2D layer. The metal–organic chains in compound 4 are linked by Keggin anions to form a 2D structure. We also studied the photocatalytic and electrochemical behavior of compounds 1–4.