Theoretical exploration on switchable NLO response induced by photochromic properties of covalently connected unsymmetrical spiropyran–polyoxometalate complex

Abstract

In this paper, the relationship between reversible redox properties and second-order nonlinear optical (NLO) responses for photochromic unsymmetrical Mn-Anderson type polyoxometalate covalently linked to one spiropyran has been systematically investigated by using density functional theory (DFT) method. It is noticeable that the second-order NLO behaviors can be switched by reversible redox for this complex. The gaining and losing of electrons cause significant change on NLO response. Among these studied systems, the β0 value of two-electron-oxidized system, SP2−, is largest and ∼48 times as large as that of system SP. The charge-transfer transition corresponding to the dominant contributions to β0 values indicates that redox processes affect on intramolecular donor and acceptor character. Therefore, this kind of complex with the facile and reversible redox states might potentially be used for switching purposes in NLO molecular devices.