Azo-8-hydroxyquinoline dyes: The synthesis, characterizations and determination of tautomeric properties of some new phenyl- and heteroarylazo-8-hydroxyquinolines
作者:Aytül Saylam、Zeynel Seferoğlu、Nermin Ertan
DOI:10.1016/j.molliq.2014.02.027
日期:2014.7
Two series of new heterocyclic and carbocyclic disperse azo dyes based on 8-hydroxyquinoline were prepared and characterized by FT-IR, H-1 NMR, mass spectroscopic techniques and elemental analysis. Their solvatochromic properties in different solvents were investigated and their absorption spectra were strongly solvent dependent The acid and base effects on this equilibrium were also examined. In addition, the colors of dyes were discussed with respect to the nature of the carbocyclic and heterocyclic rings and substituent therein. To determine the tautomeric forms of the prepared dyes in solid state, X-ray data for 5-(5-methylthiazol-2-yldiazenyl)-8-hydroxyquinoline were recorded. The X-ray results showed that the dye exists as an azo tautomer in the solid state. (C) 2014 Elsevier B.V. All rights reserved.
Solvatochromism, tautomerism and dichroism of some azoquinoline dyes in liquids and liquid crystals
Absorption and emission spectra of three hetarylazoquinoline compounds with different substituents were examined in liquids and liquid crystalline solvents for the first time. The spectral features of the hetarylazoquinoline dyes were explained according to azo/hydrazone tautomerism in conjunction with the solvatochromic characteristic of the preferred tautomer. The nature and extent of solute-solvent interactions were described using Kamlet-Taft and Katritzky multiparameter polarity scales. It was observed that solvatochromic azo/hydrazone tautomerism depend on multiple solute-solvent interactions, in particular on specific interactions and the solvent ability to transport the hydrogen atom through the media. In addition, it was concluded that anisotropic hosts prevent shift of the tautomeric equilibrium toward the hydrazone form. (C) 2011 Elsevier Ltd. All rights reserved.
Preparation of RS-Substituted 1-(Thiazo-2-ylazo)-naphthalenes by Nucleophilic Substitution of Chlorine with Mercaptans
作者:Xiuling Yu、Peter Metz、Horst Hartmann
DOI:10.1002/ejoc.201801656
日期:2019.2.14
A series of differently mercapto substituted 2‐(naphthalene‐1‐yl)azothiazoles are formed by reaction of mercaptans with chloro‐substituted 2‐(naphthalene‐1‐yl)azothiazoles in the presence of bases in the course of some simultaneously running parallel and consecutive reactions.