Synthesis, crystal structure, spectroscopic, electronic and nonlinear optical properties of potent thiazole based derivatives: Joint experimental and computational insight

Abstract Herein, two new thiazole derivatives: ethyl2-(2-benzylidenehydrazinyl)thiazole-4-carboxylate (3) and ethyl2-(2-(2-hydroxybenzylidene)hydrazinyl)thiazole-4-carboxylate (4) were synthesized by cyclization of 1-benzylidenethiosemicarbazide with ethyl bromopyruvate. The synthesis was validated by spectroscopic techniques like FTIR, 1H- NMR, 13C-NMR and chemical structure of title compounds 3 and 4 has been determined using SC-XRD. Ancillary to experimental analysis, DFT calculations with B3LYP/6-311 + G (d,p) level were performed for comparative analysis of FT-IR spectroscopic data, optimized geometry, frontier molecular orbitals (FMOs), natural bond orbital (NBO) analysis and nonlinear optical (NLO) properties. Overall, experimental findings were supported by corresponding DFT computed results. TDDFT calculations were executed at M06/6-311 + G (d,p) level of theory to calculate the vertical electronic transition states. NBO analysis disclosed that intramolecular charge transfer and hyper-conjugative interactions among bonds provide stability to the investigated compounds 3 and 4. The global reactivity parameters calculated from energy of FMOs indicates that 3 and 4 enclose larger softness and fewer hardness values. NLO results of 3 and 4 were observed better than standard molecule recommended the NLO activity of said compounds. We hope that this joint experimental and computational insight may provide new ways for the utilization of title molecules as NLO material for optoelectronic applications.