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Electronic structure and solvatochromism of merocyanines based on N,N-diethylthiobarbituric acid

Paper ID Volume ID Publish Year Pages File Format Full-Text
28398 44074 2007 11 PDF Available
Title
Electronic structure and solvatochromism of merocyanines based on N,N-diethylthiobarbituric acid
Abstract

A series of merocyanines based on N,N-diethylthiobarbituric acid containing heterocycles of various electron-donating properties have been synthesized. With the aim of studying the dependence of their electronic structure on the main structural factors (i.e. change of the terminal groups and the length of polymethine chain), and also on the solvation, their solvatochromism has been investigated in a wide range of solvents with different polarity. Moreover, their electronic structure has been studied by NMR spectroscopy and quantum-chemical calculations. It has been found a rather significant influence of the polymethine chain length on the electronic structure of merocyanines in solvents in which the condition close to the ideal polymethine state is not achieved. By analysis of the UV/vis absorption spectra in non-polar n-hexane and low-polar toluene the important role of solvation for achievement of the cyanine limit is also shown. Only for dyes with the strong electron-donating group – the benzimidazole end group – a uniformity of bond orders in the chromophore is achieved even in n-hexane with minimum participation of the solvent. These conclusions are confirmed by the data of 1H and 13C NMR spectroscopy. Attempts of correlations of the data observed with the results of quantum-chemical calculations appeared unsatisfactory, which seems to be connected to both, the lack of suitable calculation methods, and the neglect of the solvent influence.

Keywords
Donor–acceptor systems; Merocyanines; NMR spectroscopy; Solvatochromism; Electronic structure
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Electronic structure and solvatochromism of merocyanines based on N,N-diethylthiobarbituric acid
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 188, Issues 2–3, 20 May 2007, Pages 207–217
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us