New disazo dyes derived from aminopyrazoles: synthesis, spectroscopic properties, computational study and structural properties

Abstract

In this study, five new pyrazolyazo pyrazole dyestuff syntheses are reported. For this purpose, 5-amino-4-arylazo-3-methyl-1H-pyrazoles were diazotised and coupled with 3-amino-5-hydroxy-1H-pyrazole. Fourier Transform-infrared, ultraviolet-visible and proton nuclear magnetic resonance spectroscopy were used to investigate the properties of aminopyrazole-based dyes obtained in this study. The maximum absorption wavelengths of these dyes in various solvents were determined. The theoretical calculations of the molecules in the ground state were performed with the density functional theory/Becke 3-parameter and Lee-Yang-Parr/6-311G(d,p) method by using the Gaussian 0.9 W program. The results were compared with the corresponding experimental data. Acid-base and substituent effects on the absorption spectra of dyes were also examined and reported.