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Spectrochim Acta A Mol Biomol Spectrosc. 2017 Oct 5;185:111-124. doi: 10.1016/j.saa.2017.05.035. Epub 2017 May 19.

Photo-physical and structural studies of some synthesized arylazoquinoline dyes.

Author information

1
Department of Chemistry, Faculty of Science, University of Guilan, Rasht, Iran; Department of Chemistry, University Campus 2, University of Guilan, Rasht, Iran. Electronic address: aggilani@guilan.ac.ir.
2
Department of Chemistry, Faculty of Science, University of Guilan, Rasht, Iran; Department of Chemistry, University Campus 2, University of Guilan, Rasht, Iran.
3
Department of Chemistry, Faculty of Science, Lahijan Branch, Islamic Azad University, Lahijan, Iran.
4
Bioinformatics Research Center, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran.

Abstract

This study presents the spectral and structure characteristics of seven azoquinoline dyes with different substituents and their new methylated counterparts for the first time, where some compounds are newly synthesized. The solvatochromic, tautomeric, halochromic, and dichroic behavior of the compounds were studied by electronic spectroscopy in various media. The different types of media were ordinary, multifunctional, and ordered liquids. The experiments were extended to include under acidic or basic conditions. The orientational behavior of the azo dye-doped liquid crystals was studied, and it was established that the azo form is the main species in high polar anisotropic media. The multi-parameter polarity scales were used to correlate the spectral data. Influence of acid and base on the absorption spectra of the dyes was also examined. Ionization constants for these dyes were determined in ethanol-water media. As a result, at the high dye concentrations, the intermolecular hydrogen bonding is more stable than the intra-molecular hydrogen bond, and therefore, the azo form is the main species in concentrated solutions. In order to provide more details, time-dependent density functional theory (TD-DFT) calculations were carried out for the representative models.

KEYWORDS:

Azo-hydrazone tautomerism; Dichroism; Halochromism; Solvatochromism; TD-DFT calculation

PMID:
28551448
DOI:
10.1016/j.saa.2017.05.035

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