Hetarylazopyrazolone Dyes Based on Benzothiazole and Benzimidazole Ring Systems: Synthesis, Spectroscopic Investigation, and Computational Study

Abstract

In this study, the synthesized coupling component 1-(2-benzothiazolyl)-3-methylpyrazol-5-one reacted with diazotised heterocyclic amines to afford six novel hetarylazopyrazolone dyes. These azo dyes based on benzothiazole and benzimidazole ring systems were characterized by spectral methods and elemental analyses. The solvatochromic behaviors of these dyes in various solvents were evaluated. The ground state geometries of the dyes were optimized using density functional theory (DFT). Solvent, acid-base, and substituent influences on the wavelength of the maximum absorption were examined in detail. Time-dependent density functional theory (TD-DFT) calculations were performed to obtain the absorption spectra of the dyes in various solvents and the results compared with experimental values. Besides, frontier molecular orbitals (FMO) analysis for the dyes is also described from the computational process.

A Study on the Structure, Optical Properties and Cellular Localization of Novel 1,3-Benzothiazole-Substituted BODIPYs

“…1,3-benzothiazole (BZT) is a biologically important heterocycle with metabolic stability, decreased cytotoxicity and excellent cell permeability and is encountered in various bioactive compounds [38]. Furthermore, BZT has been used as a substitute in various fluorescent dyes [39], including cyanine dyes [40], pyronin dyes [41] and hetarylazopyrazolone dyes [42]. Benzothiazole-based fluorescent probes have several advantages, including high quantum yields, large Stoke shifts and high molar extinction coefficients, and have been investigated in the diagnosis of a number of disorders using imaging modalities [43].…”