Synthesis, characterization and DFT calculated properties of electron-rich hydrazinylthiazoles: Experimental and computational synergy

Rare electron-rich 1-(2-{2-[(aryl)methylidene](R-hydrazinyl}-4-methyl-1,3-thiazol-5-yl)ethan-1-ones[ArCH=NN(R)C3NS(Me)(COMe); Ar = 2-, 3- or 4-MeOC6H4, R = H, n-C5H11, CH2Ph) were synthesized (70-77%) and characterized (FTIR, HRMS and H-1-/C-13 NMR spectroscopy). In one case (Ar=3-MeOC4H4, R = H), the structure was verified by single crystal X-ray diffraction. The observed geometries are true minima, based on M06/6-311G(d,p) level DFT calculation comparisons with experimental data. Calculations were used to extract natural bond orbital (NBO) analyses and predicted non-linear optical (NLO) properties. For comparison, calculated UV-Vis absorptions and frontier molecular orbitals (FMO) analysis were computed using TD-DFT/M06/6-311G(d,p) approaches. The NBO analysis concludes that prolonged hyperconjugation and strong ICT exist in all the entitled compounds, which stabilizes the systems and also offers key evidence of charge transfer/NLO properties. Global reactivity parameters revealed chemical hardness in all molecules and efficient electron donating ability. Calculated band gaps (Egap) of 4.41-4.42 eV were realized while the compound, with all species showing high polarizability. The 4-MeOC6H4,-CH2Ph (Ar,R) compound had the highest calculated values of first hyperpolarizability (beta tot), 2975.06 (a.u) and second hyperpolarizability () (2.42 x 10(5) ). However, our X-ray results suggest that a centro-symmetric space group is favoured, unvalidating second-order NLO properties studies. (C) 2021 Published by Elsevier B.V.

Automated summary

Rare electron-rich compounds were successfully synthesized and characterized using multiple spectroscopic techniques. Calculations indicated high polarizability and nonlinear optical properties in the compounds.