Synthesis, Characterization, and Fluorescence Studies of Novel Heterocyclic Azo Dyes Derived from Benzothiazole

Ten novel fluorescent azo disperse dyes 2a – e (open forms) and 3a – e (closed forms) were obtained by the coupling reaction of carbocyclic amine based diazonium chloride with compounds 2 and 3 . The synthesized dyes were characterized by elemental analysis, high‐resolution mass spectrometry, Fourier transform infrared, and NMR spectral techniques. Moreover, we investigated the substituent effect and solvatochromic properties of the dyes on absorption and fluorescence spectra. At the same time, the absorption and emission spectral data of the closed form dyes 3a – e were compared with the open form dyes 2a – e due to more planarity of the closed form dyes that lead to the extension of the π–electron conjugation.