Crystallographic, spectroscopic and thermal studies of 1-(4-bromophenyl)-5-(2,5-dimethyl-1H-pyrrol-1-yl)-3-methyl-1H-pyrazole

Abstract

The new title pyrrole–pyrazole derivative, C16H16BrN3, was synthesized through a citric acid-catalyzed Paal–Knorr reaction between acetonylacetone and 1-(4-bromophenyl)-3-methyl-1H-pyrazol-5-amine under mild reaction conditions. This synthetic protocol is noteworthy for its utilization of stoichiometric amounts of the reactants, an ecofriendly solvent and a cost-effective, non-toxic and biodegradable organocatalyst. A comprehensive understanding of the molecular structure was gained through spectroscopic, thermal and X-ray crystallographic analyses. The crystal structure is characterized by weak interactions, where only C—H...π connections contribute to the hydrogen-bond contacts. The supramolecular assembly is controlled by dispersion forces. However, the energy frameworks demonstrate that these forces act in three dimensions, providing enough stability, as observed in TGA–DSC (thermogravimetric analysis–differential scanning calorimetry) studies.