Characterization and spectroscopic study of enzymatic oligomerization of phenazopyridine hydrochloride

Phenazopyridine hydrochloride (PHP), an azo dye, has been used in pharmaceutical chemistry. This study delineated the synthetic pathway of enzymatically oligomerized based on PHP. The molecular characterization of O-PHP was determined via UV-vis, infrared, H-1 NMR and C-13 NMR techniques. Solvent effect on the electronic absorption of O-PHP was investigated. Further analysis was fulfilled by photoluminescence (PL), thermal analysis (TG-DTA and DSC) and electrochemical (CV) measurements. PL measurements resulted in the response of O-PHP with bicolor light emissions upon Ultra-Violet and visible light, respectively. CV method was utilized to evaluate the HOMO-LUMO energy levels and the electrochemical (E-g') band gaps of the monomer and the oligomer. Optical and electrochemical band gaps of O-PHP were lower than those of PHP, confirming the accomplished synthesis of pi-conjugated structure of O-PHP. Scanning Electron Microscopy (SEM) technique was carried out to study the surface morphology of O-PHP. Additionally, the results of thermal studies of TG-DTA and DSC techniques showed that O-PHP was thermally stable compound. (C) 2019 Elsevier B.V. All rights reserved.