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Diazotisation and aso=coupling reactions have been studied and the results are reported. A kinetic study of the acid catalysed diazotisation of various aniline derivatives has been made. The substrates considered were 2,4-dinitro-aniline, 4-nitroaniline, sulphanilaraide (aniline-4-sulphonamide) and sulphanilic acid (aniline-4-sulphonic acid). A new pK(_a) value of l.4 is reported for sulphanilamide. A study of the diazotisation of sulphanilic acid and sulphanilamide in the presence of Cl¯, Br¯, SCN¯, and SC(NH(_2))(_2) shows that the general catalytic trend Cl¯ < Br¯, SCN¯ < SC(NH(_2))(_2) is followed; whereas for the corresporaing nitrosating agents the general reactivity trend NOCl > NOBr >; NOSCN >NOS(^+)C(NH(_2))(_2) is followed. No catalysis was observed in the case of 2,4=dinitroaniline and this has-been interpreted in terms of a rapid reversible nitrosation in which the rate of the denitrosation step is greater than the rate of decomposition of the intermediate nitrosammonium ion. The bimolecular rate constants obtained for sulphanilic acid and sulphanilamide approach the diffusion controlled limit for this process in the case of NOCl and NOBr, Also reported is a study of the diazotisation of two heteroaromatic amines: 2-amino-5-nitrothiazole and 3-amino-l,2,4-triazoleo Catalysis by acid and the nucleophiles Cl¯ and SCN¯ has been observed. The catalytic and reactivity trends described above have been noted for reaction of these heteroaroraaticso The Pk(_a) value for 2-amino—5-nitrothiazole has-been determined and agrees well with the literature values. In addition to the above studies of diazotisation mechanisms, results are reported of a study of the leaving abilities of various electrofugal leaving groups X during ipso=coupling of 4=nitroaniline with 4-X,N- dimethylanilineso The sequence of leaving abilities has been determined by product yield studies. Rate constants for attack of ArN(^+)(_2) have also been determined. It is suggested that a substrate molecule (X-Ar-NMe(_2)) acts as a base in removing the group X from the Wheland intermediate.

Metal and metal oxides are widely used in industry, and to optimize their performance their surfaces are commonly functionalized by the formation of thin films. Self-assembled monolayers (SAMs) are deposited on metals or metal oxides either from solution or by gas deposition. Thiols with polar terminal groups are utilized for creating the responsive surfaces which can interact electrostatically with other adsorbates. Surface charge effects wetting and adhesion, and many other surface properties. Polar terminal groups in thiols could be used to modify these factors. Mixed SAMs can provide more flexible surfaces, and could change the resulting surface properties under the influence of factors such as pH, temperature, and photo-illumination. Therefore, in order to control these phenomena by mixed polar-terminated thiols, it is necessary to understand the composition and conformation of the mixed SAMs and their response to these factors. In this work, mixtures of thiols with carboxylic and amino terminal groups were studied. Carboxylic and amino terminal groups of thiol interact with each other via hydrogen bonding in solution and form a complex. Complexes adsorb to the surface in non-conventional orientations. Unmixed SAMs from each type, either carboxylic terminated thiols or amino terminated thiols are in standing up orientation while SAMs from complexes are in an axially in-plane orientation. Selenol is an alternative to replace thiols for particular applications such as contact with biological matter which has a better compatibility with selenol than sulfur. However, the    Se-C bond is weaker than the S-C bond which limits the application of selenol. Understanding the selenol adsorption mechanism on gold surfaces could shed some light on Se-C cleavage and so is investigated in this work. Se-C cleavage happens in the low coverage areas on the step since atoms at steps have lower coordination making them more reactive than atoms on the terraces.  Another area where the self-assembly of molecules is of importance is for dye sensitized solar cells, which are based on the adsorption of the dye onto metal oxides surfaces such as TiO2.The interface between the SAM of dye and the substrate is an important factor to consider when designing dyes and surfaces in dye sensitized solar cells (DSSCs). The quality of the self-assembled monolayers of the dye on the TiO2 surface has a critical influence on the efficiency of the DSSCs.  Creation of just a monolayer of dye on the surface could lead to an efficient current of photo-excited electrons to the TiO2 and degeneration of the dye by redox. This work, T-PAC dye showed island growth with some ad-layer that is not in contact with the surface, whereas the MP13 dye adsorption is laminar growth.  Cuprite (Cu2O) is the initial and most common corrosion product for copper under atmospheric conditions. Copper could be a good replacement for noble metal as catalysts for methanol dehydrogenation. Knowledge about the structure of Cu2O(100) and Cu2O(111) surfaces could be used to obtain a deeper understanding of methanol dehydrogenation mechanisms with respect to adsorption sites on the surfaces. In this work, a detailed study was done of Cu2O(100) surface which revealed the possible surface structures as the result of different preparation conditions. Studies of the structure of Cu2O(100) and Cu2O(111) surfaces show that Cu2O(100) has a comparatively stable surface and reduces surface reactivity. As a consequence, dehydrogenation of methanol is more efficient on the Cu2O(111) surface. The hydrogen produced from methanol dehydrogenation is stored in oxygen adatom sites on both surfaces. / <p>QC 20161107</p>

Currently, functional materials are attracting considerable attention in the effort to solve some tough challenges the world is faced with. Thermochromic (TC) materials have the potential to make buildings more energy efficient because of their ability to change color (i.e black to white) at specific temperatures. Using this property, TC materials can reflect solar radiation in the summer, to keep a building cool during daytime hours, and absorb solar radiation in the winter to keep the building warm when their color is dark. Very often, to increase their durability, thermochromic materials are encapsulated. In this work, a new process has been developed to encapsulate low temperature TC materials with silicon dioxide. The encapsulated TC material has been characterized by several methods to determine its performance, such as SEM and TEM to determine the SiO2 shell structural properties, TGA and DSC to test its thermal properties. The as developed SiO2 encapsulated thermochromic materials demonstrated the color transition at around 31oC.