DFT computational insights into structural, electronic and spectroscopic parameters of 2-(2-Hydrazineyl)thiazole derivatives: a concise theoretical and experimental approach

It has been uncovered that compounds containing thiazole moiety display noteworthy biological properties, which have attracted the attention of many researchers in chemical biology as well as in medicinal chemistry. In the current examination, ten 2-(2-hydrazineyl)thiazole derivatives were studied using density functional theory (DFT). The geometry of all ten molecules was optimized by employing the DFT method with the B3LYP/6-311G (d,p) basis set. For the detailed structural and spectroscopic examination, the (E)-4-phenyl-2-(2-(1,2,6,7-tetrahydro-8H-indeno[5,4-b]furan-8-ylidene)hydrazineyl)thiazole (PIFHT) was studied as a representative molecule. The bond lengths and bond angles of the PIFHT molecule were discussed for the detailed understanding of the structural entities. The electronic parameters of all ten molecules were analyzed by computing HOMO and LUMO pictures. Using frontier molecular orbital analysis, spectroscopic and quantum chemical parameters were evaluated and discussed to explore the chemical reactivity of the molecules. Besides, absorption energies, oscillator strength, and electronic transitions of PIFHT molecule were explored using time-dependent density-functional theory (TD-DFT) at the B3LYP/6-311G (d,p) level of theory in the gas phase, dichloromethane, and dimethyl sulfoxide solvents. The TD-DFT computed theoretical UV-Visible spectra of the PIFHT molecule were compared with the experimental UV-Visible spectra. The scaled vibrational frequencies were compared with the experimental frequencies for the assignment of the vibrational bands. The comparisons between computed and experimental UV-Visible and IR spectral results are gratifying. The molecular electrostatic surface potential plots were computed for locating the reactivity sites. Mulliken atomic charges were also studied for acquiring insights into charge density.