Synthesis, PXRD structural determination, Hirshfeld surface analysis and DFT/TD-DFT investigation of 3N-ethyl-2N’-(2-ethylphenylimino) thiazolidin-4-one

Abstract The title compound, 3N-ethyl-2N’-(2-ethylphenylimino)thiazolidin-4-one (C 13 H 16 N 2 OS), was synthesized and structurally studied by IR and ( 1 H, 13 C) NMR spectroscopy. The crystal structure of the title compound was investigated using powder X-ray diffraction (PXRD) data via Direct Methods and refined by the Rietveld method. The compound crystallizes in the tetragonal system, space group I −4 with cell constants: a  = 16.99742(15) A, b  = 16.99742(15) A, c  = 9.2663(2) A, V  = 2677.15(7) A 3 , Z  = 8. The molecular geometry was optimized using the density functional theory (DFT/B3LYP) method with the 6-311G(d,p) basis set and compared to the experimental data. The experimental and theoretical structures are found to be consistent. The molecular packing of the title compound exhibits C H⋅⋅⋅O and O H⋅⋅⋅N hydrogen bonds forming supramolecular network. The details of the intermolecular interactions were studied through the Hirshfeld surface map and two-dimensional fingerprint plot. Detailed vibrational assignments and NMR chemical shifts were explored by DFT computation, showing good agreement with the experimental results. All the vibrational modes were assigned using the potential energy distribution (PED). UV–Visible spectrum in chloroform solvent was analyzed and electronic transitions involved in the title compound were predicted using the TD-DFT method. The direct and indirect band gaps were estimated using Tauc Plots via UV–Vis spectroscopy. Furthermore, the values of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy were calculated by the DFT method and their distribution was confirmed by the determination of DOS spectra. The global reactivity descriptors and the Fukui functions were evaluated. Mulliken population analysis and natural bond orbital (NBO) theory were used to compute atomic charges and the outcomes are consistent with the MEP map distribution.