Solution stage fluorescence and anticancer properties of azomethine compounds from sulpha drugs: Synthesis, experimental and theoretical insights

Abstract

In this comprehensive scientific study, we present the synthesis, characterization, and detailed analysis of two Schiff base compounds, (E)-4-((4-bromobenzylidene)amino)-N-(thiazole-2-yl)benzenesulfonamide (4BRTH) and (E)-4-((1-phenylethylidene)amino)-N-(thiazole-2-yl)benzenesulfonamide (APTH). These Schiff bases were synthesized from sulfathiazole, 4-bromobenzaldehyde, and acetophenone, employing acid-catalyzed reactions. The compounds were characterized using spectroscopic techniques, including UV, IR, and NMR. Notably, the UV spectra revealed absorption peaks at 295, 328, and 345 nm for 4BRTH and 270, 295, and 325 nm for APTH, with calculated oscillator strengths of 0.497, 0.3637, and 0.4138 for 4BRTH and 0.4841, 0.0005, and 0.1247 for APTH. Furthermore, fluorescence studies indicated unique emission peaks at 401 and 706 nm for 4BRTH and 412 and 725 nm for APTH, with excitation wavelengths at 297 nm for 4BRTH and 289 nm for APTH. The compounds displayed fluorescence characteristics, further showcasing their potential as fluorescent probes. Computational simulations were performed using various theoretical levels, including DFT calculations with the B3LYP functional and cc-pVDZ basis sets. The HOMO-LUMO gap was found to be 1.83 eV for 4BRTH and 2.04 eV for APTH, suggesting their reactivity towards other molecules. Theoretical binding energies from molecular docking studies against the breast cancer-related protein 6NLV revealed binding affinities of -18.63 kcal/mol for 4BRTH and -19.84 kcal/mol for APTH, providing insights into their potential anti-cancer activity. Moreover, in vitro anti-cancer assays conducted on MCF7 breast cancer cells demonstrated that both compounds exhibited anti-cancer activity with IC50 values. Importantly, the IC50 values were within the range of the standard anti-cancer drug cisplatin, which had an IC50 value of 62.5 μg/mL. These findings underscore the potential of 4BRTH and APTH as candidates for further anti-cancer drug development.