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Title: The use of NMR spectroscopy with in situ laser irradiation for the study of azo dye photoisomerisation
Author: Tait, Katrina Marion
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2005
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Cis-trans photoisomerisation of 4 simple disperse azo dyes and a series of reactive azo dyes has been studied by 1H nuclear magnetic resonance (NMR) spectroscopy, with an in situ laser irradiation of the sample. The laser irradiation was coupled into the sample within the NMR magnet via an optical fibre. This enabled the first 1H NMR measurements to be made of the transient cis isomers of 4-(4-nitrophenylazo)aniline, (Disperse Orange 3), and 4-[N-ethyl-N-(2-hydroxyethyl)amino]-4’-nitroazobenzene, (Disperse Red 1). Typical NMR methods including 1H 1D, 1H-1H 2D COSY and 1H-1H 2D EXSY/NOESY, were used to assign 1H resonances of the trans and cis isomers. Ab initio calculations were used to predict the chemical shifts of cis and trans isomers of the disperse dyes, in good agreement, with the experimental results, and to rationalise the chemical shift changes observed on isomerisation. The technique of NMR with in situ laser irradiation has enabled the examination of the kinetics of cis-trans isomerisation of the series of reactive dyes, showing that the technique has great potential for correlating structure with light fastness properties of dyes. The high resolution of NMR yields unambiguous kinetic information that is currently unobtainable due to the limitations of traditional methods. Calculated minimum energy structures of both cis and trans isomers of a selection of the reactive dyes serve to rationalise experimentally determined kinetics.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available