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

Ebru Aktan,Tahsin Uyar

doi:10.1155/2017/8659346

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.

Highlights

The ease of availability of raw materials and ease of preparation [1], wide range of uses as dyestuff [2, 3], advanced applications such as liquid crystal displays (LCDs) [4], nonlinear optical (NLO) devices [5], dye-sensitized solar cells (DSSCs) [6], optoelectronic systems [7, 8], and wide application areas in biological and medical studies [9] are all desirable characteristics of azo dyes
We have previously reported the synthesis, characterization, tautomeric behavior, and solvent effects on their absorption spectra of some hetarylazopyrazolone dyes with thiazole moiety together with their theoretical studies [38]
In continuation of this study, we report here the synthesis and characterization of a series of new monoazo dyes based on the benzothiazole and benzimidazole ring systems

Summary

Introduction

The ease of availability of raw materials and ease of preparation [1], wide range of uses as dyestuff [2, 3], advanced applications such as liquid crystal displays (LCDs) [4], nonlinear optical (NLO) devices [5], dye-sensitized solar cells (DSSCs) [6], optoelectronic systems [7, 8], and wide application areas in biological and medical studies [9] are all desirable characteristics of azo dyes. Various experimental and theoretical studies on the structure, tautomeric behavior, dyeing properties, and vibrational analysis of azo dyes [10,11,12,13,14,15,16,17,18,19] and their metal complexes [20,21,22] have been done. Due to their chemical significance and spectroscopic properties, hetarylazo dyes were studied extensively by spectroscopic and theoretical methods. Absorption spectra based on the DFT-optimized structures were obtained by the timedependent density functional theory (TD-DFT/B3LYP) level with the 6-31G(d,p) basis set

Experimental

Results and Discussion

Conclusions