Sulfamethazine-based azo dyes: synthesis, structural, electrochemical and fluorescence studies
Sneha Parameshwarappa, Keerthikumar T. Chinnagiri, Ramya kumari T Chinnagiri, Nirupananda Swamy
Abstract
This research aims to synthesize, analyze, and understand the redox properties of sulfamethazine-based dyes, with a particular focus on their electrochemical reactions on carbon paste electrodes (CPE). Three novel azo dyes were synthesized through a two-step process. Firstly, the diazonium salt of sulfamethazine was prepared. Subsequently, this diazonium salt was coupled with three coupling compounds: β-naphthol, α-naphthol, and 6-bromo-2-naphthol, resulting in the formation of the respective azo dyes. The structures of the synthesized colorants were elucidated using a combination of spectroscopic techniques, including FT-IR, 1H NMR, UV-Vis, and mass spectrometry. The UV-vis spectra of synthesized colorants were determined in two solvents (DMF & DMSO) between 200 and 800 nm, with the most significant absorption occurring at around 482–487 nm. Cyclic voltammetry (CV) was employed to investigate the electrochemical properties of the synthesized azo colorant at CPE. It was observed that the current corresponding to the reduction peaks of azo compounds showed a substantial change as the scan rate increased. Moreover, the plots of peak current (Ipc) versus scan rate (ν) demonstrated that the process was adsorption-controlled. In addition to that the impact of concentration of analyte(dyes) and sulfuric acid (supporting electrolyte) was also studied. Fluorescence properties were further investigated in two solvent systems, DMSO and DMF. Notably, compounds M1&M2 displayed significantly enhanced fluorescence intensities and quantum yields in both media.