Carbazole-Based Mono and Bis-styryl NLOphores: Structure Property Correlations

Abstract

A detailed study of linear and nonlinear optical (NLO) properties obtained by spectroscopy and DFT computations of carbazole-based D-π-A (mono) and A-π-D-π-A (bis) extended styryl dyes is presented. Four different DFT functionals, B3LYP, MO6, BHandHLYP, and CAM-B3LYP are used for computations. The structure–property relationship is examined by correlating bond length alternation/bond order alternation with NLO properties of the dyes. The bis-carbazole styryl dyes possess a higher second-order hyperpolarizability (β) than the mono-carbazole styryl dyes. An increase in the polarity of the environment causes an increase in the first-order hyperpolarizability (β CT or β 0) and second-order hyperpolarizability (γ) of the mono- and bis-carbazole styryl compounds. The NLO properties calculated by the CAM-B3LYP and BHandHLYP functionals show good agreement with the spectroscopic results.