Novel Thiazole Based Styryl Dyes with Benzimidazole Unit - Synthesis, Photophysical and TD-DFT Studies.

Three new Y-shaped styryl dyes were designed and synthesized from thiazole carbaldehyde with different active methylene compounds as acceptor moieties. All the dyes were characterized by IR,1 HNMR, MS/LCMS/HRMS. Spectroscopic properties and non-linear optical properties styryl derivatives were analyzed and the effect of change in solvent polarity on their absorption and emissive properties has been investigated. The dye with (1-phenylethylidene) propanedinitrile unit shows red shift absorption/emission profile among all the dyes. Density Functional Theory and Time Dependent-Density Functional Theory computations have been used for comparative study with the experimental data and also to understand the structural, molecular, electronic and photophysical parameters of the styryl dyes. The computational method was also employed to investigate the nonlinear optical properties of the styryl dyes in different organic solvent. The unsubstituted benzimidazolyl thiazole styryl dyes possess good non-linear optical properties.