Synthesis, spectroscopic characterization, computational and electrochemical studies of sulfamethazine based azo dyes

Present work describes the synthesis of heterocyclic azo dyes derived from sulfamethazine. The dyes were synthesized by the diazotization of sulfamethazine and coupling reactions with four coupling compounds - barbituric acid, thiobarbituric acid, dimethyl barbituric acid, and 4-hydroxy coumarin. Dyes were isolated in a good yield (70–75 %) and observed orange-red and yellow color. The synthesized dyes were characterized using physical and analytical method. DFT studies were conducted by the B3LYP/6–311 + g (d, p) basis set using Gaussian 09 W program, in gaseous phase result the optimized geometry, Quantum chemical parameters, band gap and MEP. The synthesized compound R4 exhibits a relatively lower energy gap compared to the other azo compounds (R1, R2, and R3). Since chemical hardness is inversely proportional to the reactivity of azo compounds. R4, having the lowest energy gap, is the most reactive among the synthesized azo compounds . Electrochemical studies revealing distinct redox peaks that were observed at increasing scan rates. Furthermore, experimental calculations of the energy gap were performed based on using cyclic voltammetry studies in electrochemical redox potentials and compared with theoretical values give a thorough explanation of the electrical properties of the derivatives. Graphical Abstract • Dyes were synthesized by the diazotization of sulfamethazine and coupling reactions with four various coupling components. • Computational studies: Quantum chemical parameter, optical geometry compound, electrostatic potential map • Cyclic voltammetry studies in electrochemical redox potentials and compared with theoretical values. • Simultaneous studies in dyes and biomolecule.