Spectral, Thermal Behavior, Molecular Modeling, and Antimicrobial Studies of Fuchsin Basic Hydrochloride

Abstract

The current study reported important characteristic features of the 4‐[(4‐aminophenyl)‐(4‐imino‐3‐methylcyclohexa‐2,5‐dien‐1‐ylidene)methyl]aniline hydrochloride known as fuchsin basic dye (FB). The thermal decomposition behavior of the dye was scrutinized through thermogravimetric analysis (TG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). Besides, the acid dissociation constants of FB were evaluated by analyzing its electronic spectra at different pH values. In addition, a docking study was also carried out to investigate the binding affinity between the FB dye and two selected proteins (3t88 and 1bqb) of Escherichia coli and Staphylococcus aureus, respectively. The docked complex of the dye with the target proteins exhibits moderate scoring energy values (−5.2025 and −5.5762 kcal/mol where the receptors are bonded to the dye through H‐bonds of lengths that are less than 3.5 Å. The dye was also tested for its antimicrobial activity against two Gram‐positive and two Gram‐negative bacterial species. The results revealed moderate to good activity against Klebsiella pneumonia, Escherichia coli, and Streptococcus pyogenes species compared to amoxicillin 0.1 % as a reference control.