Nonlinear optical response of a series of small molecules: quantum modification of π-spacer and acceptor

Abstract: In this research article, a series of compounds have been designed to investigate the nonlinear optical (NLO) response. The electronic structures, absorption spectra and nonlinear optical response have been calculated by employing quantum chemical methods. The new design of dyes has been proposed by the structural modification of π-spacers/conjugated systems (CS) and terminal acceptors (TA). The quantum modeling and design is based on three phases; in every phase different π-spacer (CS1–CS2) with the acceptors (TA1–TA5) are used around central quinoxaline group. DFT and TDDFT calculations are performed to shed light on how structural modification influences the NLO properties. Polarizability (α), hyperpolarizability (β) and absorption wave length are calculated. These strategies indicate that the thiazole-based conjugated systems (CS2) offer relatively an effective way to improve NLO response. This theoretical framework might be useful to design other organic dyes in the field of electro-optics. Graphical Abstract: The DFT and TDDFT calculations have been performed to shed light on how structural modification influences the NLO properties. Impact of various terminal acceptors (TA) and conjugated systems (CS) has been systematically studied.