Novel sulfonamide-quinoline azo derivatives: Synthesis and comprehensive investigation of their biological, photophysical, and electrochemical properties

In this study, we reported the synthesis, characterization, and multifaceted evaluation of four new quinoline-based azo compounds (S1–S4) derived from different sulfonamides. Prepared via an electrophilic substitution reaction, their structures were elucidated using a comprehensive suite of analytical techniques, including FTIR, NMR (¹H and ¹³C) and mass spectrometry. Their photophysical properties were examined through fluorescence and UV-vis spectroscopy in DMF and DMSO at varied pH levels, with quantum yields also calculated. The biological activity assessment indicated that compound S3 possessed marked cytotoxic properties against human breast cancer cells (MDA-MB-231), exhibiting an IC₅₀ value of 9.07 μg/mL. In parallel, compound S2 demonstrated good antibacterial activity against Escherichia coli and Staphylococcus aureus , with molecular docking studies indicating DNA gyrase as a probable target. An investigation of the dyes' electrochemical characteristics was carried out by performing cyclic voltammetry at a carbon paste electrode (CPE). Analysis of scan rate dependency revealed that the reduction process was adsorption-controlled for S1 and S2, whereas it was diffusion-controlled for S3 and S4. These collective findings underscore the promise of sulfonamide–quinoline azo derivatives as versatile agents for both therapeutic and electrochemical applications.