Non-linear Optical Response of Phenoxazine-based Dyes: Molecular Engineering of Thiadiazole Derivatives as pi-spacers

In this article, various dyes have been quantum chemically designed which are based on A-pi-D-pi-A structural configuration. The main objective of this work is to study the effect of electron deficient thiadiazole derivatives as the pi-spacers. The role of these pi-spacers in phenoxazine-based dyes have been studied through electronic, non-linear optical (NLO) and absorption properties. The electronic structures, absorption spectra and NLO response were calculated by employing quantum chemical methods. The results reveal that the polarizability (alpha) and hyperpolarizability (beta) remarkably increase from dye 1 to dye 5. As compared to model of dye 1, dyes 2-5 have shown red-shifted absorption spectra and low band gaps.