نوع مقاله : مقاله پژوهشی
گروه شیمی، دانشکده علوم، واحد لاهیجان، دانشگاه آزاد اسلامی، لاهیجان، گیلان، صندوق پستی: 1616
عنوان مقاله [English]
In this study, two 2-aminobenzothiazole derivatives were prepared by the reaction of appropriate substituted anilines with potassium thiocyanate in acetic acid followed by mild cyclization oxidation reaction with bromine at room temperature. Then, 2-aminobenzothiazole and each of the two synthesized amines were diazotized with nitorsyl sulfuric acid and coupled with 5-chloro-8-hydroxy quinoline to prepare corresponding heteroarylazo dyes. Their solvatochromism was evaluated in different solvents. The effects of acid and base on the absorption maximum wavelengths of the compounds were also studied. From the optical spectra, in each case, the isosbestic points indicate that the two species are in equilibrium. For all of the compounds under investigation, the dependence of the absorbance on the pH value gives sigmoid curves. The acidity constants (pKa) of the dyes were also determined using the spectrophotometric method in an ethanol-water mixture (80:20, v/v) at 20-23°C. Besides, density functional theory (DFT) calculations were carried out in order to compare the energies of proposed azo and hydrazone tautomers of the dyes.