Computational Study on Redox-Switchable Second-Order Nonlinear Optical Properties of Totally Inorganic Keggin-Type Polyoxometalate Complexes

Abstract

The electronic structure and second-order nonlinear optical (NLO) property of a series of monoruthenium-substituted Keggin-type polyoxometalates (POMs) have been studied by using density functional theory (DFT) and time-dependent (TD)DFT calculations. The DFT calculation supports that these POM complexes possess donor-π-conjugated bridge-acceptor (D-π-A) structure, which the ruthenium atom acts as the role of electron donor and the three vanadium atoms in cap region of Keggin-type POM act as the role of electron acceptor. It is well-known that D-π-A structure, as a simple molecular scheme, has been successfully used in the development of organic NLO materials. However, the totally inorganic molecule having D-π-A structure is very rare. Thereby the second-order NLO properties of these POM complexes have been analyzed in this work. According to the calculations, introduction of the electron acceptor leads to a substantial enhancement on the second-order NLO response. The calculated βHRS(−2ω; ω, ω) value of ...