Theoretical exploration on switchable NLO response induced by redox properties of polyoxometalates [XNbW11O40]n−/(n+1)- (X = Al, Si, P, S, Ga, Ge, As, Se)

Abstract

Calculations based on density functional theory (DFT) have been performed to investigate the relationship between redox properties and second-order nonlinear optical (NLO) responses of Keggin-type anions [XNbW11O40]n− (X = Al, Si, P, S, Ga, Ge, As, Se) and their corresponding heteropoly blues. The frontier molecular orbitals, NLO responses and electronic transition properties of fully oxidized anions and heteropoly blues were discussed. It is noticeable that the second-order NLO behaviors can be switched by reduced electrons for these Keggin-type anions. The calculated β0 value of heteropoly blues [XNbW11O40](n+1)- (X = P, As, S) are 21–23 times as large as those of fully oxidized anions [XNbW11O40]n− (X = P, As, S) according to CAM-B3LYP/6-31G* (LANL2DZ basis sets for metal atom) calculations in CH3CN. The aim of this work is to combine the attractive redox properties and NLO response of polyoxometalates to obtain the switchable NLO materials.