City Research Online

Abstract

The basic concepts of Photochemisty and the phenomena of colour are outlined.

The chemical nature of wool is briefly described and a review of its photochemistry presented. For convenience the photochemical reactions are separated into two main categories which are free radical reactions and processes leading to the photoyellowing of wool. The photochemistry of Fluorescent Brightening Agents (FBA's) is discussed with reference to oxidative and reductive reactions. Processes leading to the prevention of wool photoyellowing are outlined.

A reactive FBA has been synthesised and coupled with various polyamines. These adducts were found to be a complex mixture when analysed by HPLC. Nevertheless they were applied to wool by a standard exhaustion method and crosslinked with formaldehyde and a thiourea/formaldehye (TUF) precondensate. These adducts were not as fluorescent as a commercial FWA due to the presence of the amine groups. Extraction experiments showed that more FBA was bound to the wool after crosslinking with formaldehyde and TUF than uncrosslinked FBA. Use of high thiourea concentrations in the TUF treatment gave the wool good lightfastness even though the fluorophore was destroyed.

A reactive azo dye was synthesised and reacted with diethylenetriamine. This adduct was applied to wool at 60 C and 100 C and crosslinked with formaldehyde, TUF and phosphorous reducing agents. When applied and crosslinked at the lower temperature of 60 C the dye was almost completely extracted with organic solvents. However, when the dye was applied and crosslinked at 100 C only 50% was removed by extraction with the same organic solvents. In the presence of reducing agents the dye photodegradation was accelerated.

N-Formylkynurenine and several N-formylated indoles and aromatic amines were synthesised and their photochemistry studied. Simple N-formyl indoles and amines were readily decarbonylated at 254 and 300 nm irradiation. Compounds with a ketone carbonyl conjugated to the chromophore underwent decarbonylation when irradiated at 254 nm but only degraded to give unidentified products on 300 nm irradiation. Oxygen and water did not affect the reaction rate which followed first order kinetics. A reaction mechanism which fits the experimental observations is proposed.

The use of azlactones as coloured compounds has been investigated. Thus three different classes have been synthesised with respect to the aromatic substituents. The classes are donor - acceptor, polycyclic and organometallic azlactones. Their spectroscopic properties have been studied and the transitions leading to the long wavelength Uv / Vis absorption assigned. It is possible to explain why some azlactones are fluorescent and others are not. Reaction with nucleophiles such as amines, thiols and water leading to ring opened, products and other heterocycles are described. The changes in photophysical properties are discussed and compared to the parent compounds. A fluorescent azlactone containing an isothiocyanate reactive group was found to be unsuitable to label proteins because of undesired side reactions. A series of heterocycles was used to dye polyester. The solid state fluorescence spectra were compared to the solution spectra. The light fastness of the dyes were discussed with reference to their structures.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > QD Chemistry
Departments:	Doctoral Theses School of Science & Technology School of Science & Technology > School of Science & Technology Doctoral Theses

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