Vibrational and electronic signatures of bromo-substituted Schiff bases: Thermal stability and molecular docking studies

This investigation investigates the structure-property correlations in four new bromo-substituted Salicylidenes (A–D), exhibiting the impact of electronic substitution on corresponding thermal steadiness, photophysical properties, as well as tentative α-amylase inhibitory activity assessed using molecular docking. Spectroscopic elucidation proved the generation of both typical C=N imine bonds and intramolecular O–H···N hydrogen bonding in all derivatives. Schiff base D, presenting highly electron-accepting group NO₂ moiety, exhibited the best performing profile: it showed the best thermal stability (∼ 64% residual mass), the highest Stokes shift (837.9 cm^-1), in addition to the largest optical band gap (3.73 eV). A computational molecular docking investigation was performed to predict that Salicylidene D also presented a relatively high binding affinity (ΔG = -7.9 kcal/mol) to the α-amylase enzyme (3BAJ), principally via π–π stacking interactions with key TRP residues. These findings show the key role of substituent's effect in tailoring the purposeful characteristics of Salicylidene derivatives, identifying the nitro-substituted derivative D as a leading compound for extended studies, including deeper TD-DFT computational studies, experimental antidiabetic applications, and optoelectronic material's design.