Synthesis, characterization and DFT study of a new family of pyrazole derivatives

This work deals about the synthesis and characterization of compounds containing the pyrazole core belonging to the family of (E)-4-((3,5-dimethyl-1-(4-R-phenyl)-1H-pyrazol-4-yl)diazenyl)benzonitrile, with possible application as ligands in inorganic chemistry. These compounds were obtained by reaction of a substituted arylhydrazine, RC6H4NHNH2, R: 4-OCH3, 4-CH3, 4-F, 4-H, 4-Cl, 4-CF3, 4-CN, 3-Cl, 3-NO2, 2-Cl and perfluorophenylhydrazine, C6F5-NH2NH; with a β-diketohydrazone precursor of formula (CH3CO)2CNNHC6H44-CN. Analytical techniques (MP and EA) and spectroscopic methods such as UV–Vis, IR, 1H NMR, 13C NMR were employed to characterize the prepared systems. One of the synthesized compounds yielded in ethanol single crystals suitable for X-ray diffraction study. In order to model all the studied compounds and the molecular orbitals involved in the transitions, DFT and TDDFT calculations were performed. The non-variability of the bond distances suggests the robustness of the conjugated structure formed by the RC6H4pyrazoleNNbenzonitrile rings, which is poorly affected by the change of the substituents over the phenyl ring.

Graphical abstractSynthesis and characterization of compounds containing the pyrazole nuclei.Figure optionsDownload full-size imageDownload as PowerPoint slide