A Computational Strategy for the Design of Photochromic Derivatives Based on Diarylethene and Nickel Dithiolene with Large Contrast in Nonlinear Optical Properties

Abstract

We designed a series of photochromic derivatives by employing density functional method (CAM-B3LYP/6-31G*). These compounds are based on DAE (diarylethenes), both sides of which are bonded with benzene and NiBDT (bis(ethylene-1,2-dithiolato)Ni). These substituents and, in particular, the NiBDT moiety are known to exhibit very large second hyperpolarizability. The objective of this work was to develop, by employing a DFT methodology, a set of rules for designing photochromic materials presenting the following: (i) a large contrast between a series of physical properties-the hyperpolarizabilities (first and second), the IR absorption and the two-photon absorption (TPA) strength-of the "open" and the "closed" isomers and (ii) extremely large nonlinear optical properties. This large contrast may be attained by a light-induced transformation of the "open" to the "closed" isomer, combined with substituents involving an extensive π-electron network and/or strong donor/acceptor pairs. Copyright © 2020 American Chemical Society.