Synthesis and theoretical study of a new family of pyrazole derivative

•synthesize a series of pyrazole derivates.•characterized by UV–vis, FTIR, 1H-NMR, and 13C-NMR•DFT and Hammet correlation were performed. Pyrazole-containing molecules are key in the development of new pharmaceuticals or pesticides. Thus, we synthesize a new series of pyrazole derivates using the cycloaddition methods. The synthesized compounds present a (E)-4-((4-iodophenyl)diazenyl)-3,5-dimethyl-1-(R-phenyl)-1H-pyrazole structure. The compounds were characterized by UV-vis, FTIR, 1H-NMR, and 13C-NMR. Also, DFT and Hammet correlation calculations were performed over the whole family of derivatives. Our results demonstrate that the synthesized compound was obtained with a overall yield of 50 %. UV/Vis spectroscopic characterization shows that all compounds present three absorption bands related to the pyrazole ring, the -N=N- bond and benzene rings. Additionally, theoretical calculation shows that the dihedral angle decreases when the electron-attractive nature of the substituent of the pyrazole ring increases. Finally, Hammett correlation studied shows a good fit in some of the measured properties.