A series of POM-based compounds constructed by mono- and mixed-ligands synergetically: structures, electrochemical and selective photocatalytic properties

Abstract

By using pyrazine (pz) and its derivatives 2,3-naphthalenylphenazine (npz) and 2,3-diphenylpyrazine (dpz), one Lindqvist- and six Keggin-based compounds, [AgI2(npz)4(W6O19)]·npz ( 1 ), [AgI2(npz)3(HPW12O40)] ( 2 ), [AgI3(npz)4-(PMo12O40)] ( 3 ), [AgI4(pz)5(SiMo12O40)] ( 4 ), [AgI4(npz)2(pz)(PMoVMo11VIO40)] ( 5 ), [AgI4(npz)4(dpz)2(H2O)2(SiW12O40)] ( 6 ) and {AgI5KI2(npz)4(dpz)2[H(PWVW11VIO40)2]} ( 7 ), have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analyses. In compound 1 , there is a distorted “I”-type [Ag(npz)2]+ subunit with two npz arranging vertically. Two [Ag(npz)2]+ subunits support the [W6O19]2− anion symmetrically. In compound 2 , there are [Ag2-(npz)3]2+ clusters with one linking and two terminate npz, which are further linked by [PW12O40]3− anions to form a “sunrise”-like chain. In compound 3 , there exist a discrete [Ag2(npz)3]2+ cluster and a mono-supporting anion [AgI(npz)- (HPW12O40)]−. In compound 4 , there are two kinds of cycles in honeycomb-like Ag-pz layer: six-membered cycle I and eight-membered cycle II. An anion dimmer linked by a AgI ion embeds in bigger cycle II. In compound 5 , one pz and two npz are connected by four AgI ions to build a linear [Ag4(npz)2(pz)]4+ subunit. The PMo12 anions link the linear subunits alternately and a 1D chain is formed. In compound 6 , there exists discrete [Ag2(npz)2(dpz)(H2O)]2+ subunit and Keggin anion. In compound 7 , the Keggin-K inorganic chains are connected by AgI-npz-dpz subunits to form a 2D layer. The adjacent layers are further linked by anions to build a 3D framework. Moreover, we also have investigated the electrochemical and photocatalytic properties of 1 -- 7 .