Three new POM-based compounds constructed by rigid thiabendazole and flexible bis(pyrazole) ligands: structures and properties for Hg²⁺ recognition

Abstract

By using mixed rigid and flexible organic ligands, three Keggin based compounds, [Ag6(tbz)4(bmz)2(H3PW12O40)]·4H2O (1), [Ag(H2bdpm)2(H2PMo12O40)]·7.5H2O (2), and [Ag4(tbz)2(H2bdpm)2(HPMo12O40)]·2H2O (3) (Htbz = thiabendazole, Hbmz = benzimidazole, H2bdpm = 1,1'-bis(3,5-dimethyl-1H-pyrazolate)methane), were hydrothermally synthesized and structurally characterized. Through adopting rigid Htbz ligands, compound 1 with hexa-nuclear Ag(I) clusters has been obtained. These hexa-nuclear clusters are linked by Keggin anions alternately to form a one dimensional (1D) chain. In compound , the organic moiety is the flexible H2bdpm ligand. The Keggin anions are fused by [Ag(H2bdpm)2](+) subunits to form a 1D chain. In compound 3, the rigid Htbz and the flexible H2bdpm cooperate to modify the anions. Two tbz and two H2bdpm are fused by four Ag(I) ions to construct a tetra-nuclear Ag(I) cycle. The anions connect these cycles through Ag-O bonds alternately to form a 1D chain. Adjacent chains arrange parallel to build a 2D layer. The chains in the adjacent layers are vertically packed and linked by Ag-O bonds to construct a 3D framework. The electrochemical and photocatalytic properties of the title compounds have been studied. Furthermore, we have also studied the Hg(2+) recognition properties in a suspension of compounds 1 and 3.