Synthesis of Some New Heterocyclic Azo Dyes Derived from 2-amino-3-cyano-4.6- diarylpyridines and Investigation of its Absorption Spectra and Stability using the DFT

Introduction: In continuation of our interest in 2-amino-3-cyano-4.6-diarylpyridines reactions in various fields of organic chemistry which were previously used for the synthesis of many heterocyclic compounds and where dyes generally have many applications especially when benzene or anthraquinone azo dyes are replaced with heterocyclic azo dyes so new derivatives of heterocyclic azo dyes derived from 2-amino-3-cyano- 4.6-diarylpyridines were prepared. Materials and Methods: The IR spectra (KBr), NMR, elemental microanalyses and mass spectra, were performed at different faculties of science in Egypt. Absorption spectra were recorded on Unicam SP 750 in DMF and acetone using 1x 10^-5 mol l^-1 of dye concentration. Optimization was performed using density functional theory (DFT) and time dependent-DFT by applying Becke’s three-parameter hybrid exchange functional with Lee– Yang–Parr gradient-corrected correlation (B3LYP functional). The chemical reagents used in the synthesis were purchased from Fluka, Sigma and Aldrich. Results and Discussion: The structure of the preparing Heterocyclic azo dyes is proven using spectroscopic tools and elemental analysis, and investigation of its absorption spectra indicate the effect of both solvent and substituent on absorption maximum. DFT calculations were performed on some of the selected dyes. Conclusion: Structures of newly synthesized heterocyclic azo dyes were confirmed using elemental analysis, IR, ¹H-NMR, ¹³C-NMR and mass spectral data. DFT theory was used in explaining the electronic properties of some selected dyes, where the energy gap can help in understanding the reactivity behaviour and stability of these compounds. Absorption spectra indicate the effect of both solvent and substituent on absorption maximum.