Part 1: Synthesis and visible absorption spectra of some new monoazo dyes derived from ethyl 2-amino-4-(4′-substitutedphenyl)thiophenes

Abstract

Series of monoazo dyes from some ethyl 2-amino-4-(4′-substitutedphenyl) thiophenes were prepared and characterized. The structure of the substances was confirmed by FT-IR, 1H NMR and mass spectroscopic techniques. The relationship among the structure of the dyes, their absorption characteristics and the solvatochromic and halochromic behaviors of the dyes were investigated. Introduction of electron-accepting substituent into the diazo moiety results in large bathochromic shifts in all solvents used. The dyes exhibited positive solvatochromism and their solvatochromic properties were discussed in relation to tautomerism.