This PhD is in the intersect between teenagers (as users of IT), social interaction (as an activity), and mood (as a driver for concern). It considers teenagers’ moods through an interactive colour sharing social product. It builds on studies of colour and colour preference with adults and on the effect of colour on mood and behaviour from interior design and architecture. The aim is to investigate the extent to which, and the context in which, certain colours reflect teenagers’ mood and feelings whilst also studying the behaviours of teenagers in communicating their moods with their friends.

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6-Bromo-, 7-bromo-, 8-bromo- and 6,8-dibromo- 2,2-dimethylchromenes have been synthesised. The 6-bromoand 8-bromo-derivatives were prepared by Claisen rearrangement of aryl propargyl ethers, derived from phenols and 3-chloro-3-methylbut-1-yne. 7-Bromo- and 6,8-dibromo-2,2-dimethylchromenes were obtained by dehydration of the corresponding chroman-4-ols, available from the chroman-4-ones. Addition of bromine to the chromenes gave the corresponding 3,4-dibromochromans which were hydrolysed with aqueous acetone to yield the 3-bromochroman-4-ols. These chromanols were also obtained directly from the chromenes by reaction with N-bromosuccinimide in moist dimethyl sulphoxide. The bromohydrins were oxidised to 3-bromochroman-4-ones and conversion to the chroman-4-ones was achieved by subsequent reaction with benzo±n. The same chroman-4-ones have been synthesised by the condensation of the appropriate brominated 2-hydroxyacetophenories with acetone in the presence of pyrrolidine. Róduction of the chroman-4-ones using sodium borohydride afforded the chroman-4-ols. The bromohydrins have been converted to the corresponding 3,4-epoxychromans and ring opening reactions with lithium aluminium hydride, hydrobromic acid and methanol were studied. Dehydration of the 3-bromochroman- 4-ols yielded the 3-bromochromenes. The isomeric 4-bromochromenes resulted from treatment of the -- - 3,4-dibromochromans with sodium methoxide. Routes to 2,2-dimethylchroman-4-ones based on the Fries rearrangement of phenyl 3-methylbut-2-enoates and the reaction between a phenol and 3-methylbut-2-enoic acid have been examined. In many instances, the isomeric 3,4-dihydro-4,4-dimethylcoumarins were formed either as sole products or admixed with chromanones. Treatment of 4-bromo- 1 6-bromo-, 7-bromo- and 8-bromo-2 ,2-dimethylchromenes with n-butyl-lithium followed by Michler's ketone has given a series of dyes related to Malachite Green, h'.it incorporating an oxygen heterocyclic function. The 6- and 7-bromochromenes gave longitudinally conjugated dyes, whereas transversely conjugated dyes resulted from the 4- and 8-bromochromenes.

Thermochromic materials undergo temperature-dependent colour changes. Although there are several origins of thermochromism, two distinct types of thermochromism are common in thermochromic mixtures. Melt-lightened thermochromism occurs when the colour density of a mixture decreases with increasing temperature, and is usually associated with colour loss upon mixture melting. Melt-darkened thermochromism occurs when the colour density of a mixture increases with increasing temperature, and is usually associated conversion from a decoloured solid state to a coloured melt. Three-component thermochromic systems generally consist of a leuco dye (minor component), a phenolic colour developer (intermediate component), and a high melting-point organic solvent (dominant component). In these systems, the colouring behaviour is controlled by competing binary interactions, with the dye:developer interaction responsible for colour formation and the developer:solvent interaction responsible for colour erasure. In the present study, three-component mixtures composed of CVL (dye), long-chain alkyl gallates (phenolic developer), and long-chain alkyl alcohols (long-chain solvent) were examined. The thermochromic behaviour (i.e., melt-lightened vs. melt-darkened thermochromism) of these mixtures was examined as a function of the matching of the alkyl chain length of the gallate developer and alcohol solvent. When the alkyl chain lengths were well matched, the developer:solvent interaction dominated in the solid state and melt-darkened thermochromism was observed. When the alkyl chain lengths were poorly matched, the dye:developer interaction dominated in the solid state, and melt-lightened thermochromism was observed. The colour density of the molten state was determined by the developer:dye molar ratio, with high molar ratios yielding coloured melts and low molar ratios yielding decoloured melts. Additional studies employing chemically dissimilar developers and solvents (e.g., bisphenol A with 1-hexadecanol) yielded mixtures that displayed optimal melt-lightened thermochromism. The high solid-state colour density due to weak developer:solvent interactions provides further evidence that competing binary interactions are responsible for the colouring behaviour observed for three-component thermochromic systems. Ternary thermochromic phase diagrams were used to define compositional regions of optimal thermochromic behaviour (i.e., high colour contrast), providing a useful experimental tool for the rapid identification of ideal sample compositions. Additionally, an examination of the properties of thermally erasable ink-jet printer inks was carried out during the present study. / An assessment of the thermochromic behaviour of three-component chemical systems comprising a colour-changing leuco dye, an electron-accepting phenolic developer, and a long-chain alkyl alcohol solid solvent.