Synthesis, spectroscopic characterization, DFT studies and antioxidant activity of new 5-substituted isatin/thiosemicarbazones

Abstract

A new series of thiosemicarbazone derivatives (1–8) were prepared and elucidated by FT-IR, 1H NMR, and 13C NMR spectroscopic methods and elemental analysis. In this study, in which the antiradical activities of 1,1-diphenyl-2-picrylhydrazil (DPPH) were investigated, ascorbic acid was used as a reference antioxidant. Also, density functional theory (DFT) calculations were employed to investigate the structural and electronic properties of compounds, and the obtained data were utilized to elucidate antioxidant activity. In summary, the half maximal inhibitory concentration (IC50) values were calculated and had lower antioxidant activity than the standard ascorbic acid.