Studies in the photochemistry of dyed proteins and other related systems

Baxter, George (1957) Studies in the photochemistry of dyed proteins and other related systems. PhD thesis, University of Glasgow.

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The literature on the light fastness of dyes is first reviewed. In the first part of the present investigation previous work upon the influence of the substrate on the nature of the fading reaction has been followed up; in this, a series of water-insoluble benzene-azo-2-naphthol dyes, substituted in the benzene nucleus meta- and para- to the azo group has been introduced into cast collodion films and faded. The results are discussed, taking account of the sign of the gradient obtained from the curve of relative fading rate versus the Hammett 6- value of the substituent group in the dye. The results agree with those previously reported, and in addition, show much less random error. The main source of error appears to be the non-uniform physical state of the dyes in the substrates. The influence of the physical state of the dye has next been investigated, with reference to a theoretical model system, developed on the basis of observations made upon the fading of certain water-insoluble dyes in markedly different states of dispersion in solid substrates. The model system has been applied to tests on water-insoluble dyes and allows logical explanation to be given for all observed effects. Its application has been extended to the case of water-soluble dyes on solid substrates and it would seem from the data obtained that these dyes are also present in the fibre as discrete, sub-microscopic particles or aggregates, the size and nature of which are dependent upon the physical characteristics of the dye:substrate system. In the final section of the work the influence of the surface activity of dyes upon their light fastness has been studied, alterations in the surface activity being produced by changes in the size and form of the hydrophobic residues and the position of the ionic groups in the dyes. It has been concluded that the position of these groups in the dye molecule can affect the light fastness, by virtue of its influence upon the physical form which the dye assumes when the substrate is dried out. This suggestion is supported by the agreement shown with the predictions of the theoretical model for heterogeneous dye systems. In particular, dissymmetric dye molecules, which are believed to form monolayers most readily, have been observed to give relatively rapid fading.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: C H Giles
Keywords: Physical chemistry
Date of Award: 1957
Depositing User: Enlighten Team
Unique ID: glathesis:1957-73567
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56

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