Synthesis, structure and solvatochromic properties of novel dyes derived from 4-(4-nitrophenyl)-3-cyano-2-pyridone

Abstract

A series of ten new 5-arylazo-6-hydroxy-4-(4-nitrophenyl)-3-cyano-2- pyridone dyes was synthesized using a classical reaction for the synthesis of azo compounds. The structure of the dyes was confirmed by melting point, elemental analysis, UV-vis, FT-IR, 1H NMR and 13C NMR spectroscopic techniques. The absorption spectra were recorded in twenty solvents of different properties in the range of 300-700 nm. In order to describe the spectral changes and the solute-solvent interactions, multiparameter Kamlet-Taft and Catalan solvent scales were used. The Catalan solvent scales are found to be the most suitable for describing the solvatochromic behavior of the synthesized dyes. The effect of the substituents on the azo-hydrazone tautomeric equilibrium was analyzed using the simple Hammett equation. For the synthesized dyes, the Hammett polar susceptibility constant (ρ) was correlated through multiple regression using appropriate solvent parameters. © 2014 Elsevier B.V.