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Vapour pressures over the temperature range 293-405 K, have been measured, for some metal beta-diketonates, using the Knudsen effusion technique. Heats of sublimation have been derived from the vapour pressure/temperature data, by means of the Clausius-Clapeyron relationship, for the following complexes: Be(acac)2 DeltaHsub. = 94 +/- 1kJ.mol-1 Hacac = acetylacetone. A1 (acac)3 DeltaHsub. = 120 +/- 3 kJ.mol-1. Cr(acac)3 DeltaHsub. = 123 +/- 3 kJ.mol-1. Be (tfacac)2 DeltaHsub. = 88 +/- 4 kJ.mol-1 Htfacac = trifluoro-acetylacetone. A1 (tfacac)3 DeltaHsub. = 108 +/- 2 kJ.mol-1. Be(dpm)2 DeltaHsub. = 102 +/- 3 kJ.mol-1 Hdpm=dipivaloylmethane. al(dpm)3 DeltaHsub. =119 +/- kJ.mol-1 These results have been correlated with various properties of the metal complexes, including stereochemistry, crystal packing, molecular polarity and steric effects. The design of the Knudsen effusion apparatus was decided on after a detailed analysis of theoretical and practical aspects of the technique. Heats of solution at 298.15K for Be(acac)2, Be(tfacac)2, Be(dpm)2, Al(acac)3, Al(tfacac)3, Al(dpm)3, Cr(acac)3, Fe(acac)3, Co(acac)3 in carbontetrachloride; Be(acac)2, Be(tfacac)2, Be(dpm)2, Al(tfacac)3, Al(dpm)3 in benzene and Be(acac)2, Be(tfacac)2, A1(tfacac)3 in chloroform have been measured using the LKB-8700 Solution Calorimeter. Heats of solvation were derived from heats of sublimation and solution for the following complexes: [table] Solvation energies have been interpreted in terms of interaction characteristics of both solvents and complexes. The higher solvation energies in chloroform with respect to the other solvents can be attributed to some form of hydrogen bonding.

A statistical thermodynamic treatment has been successfully applied to several uni-univalent and uni-bivalent anion exchange reactions, with, in the latter case, an empirical correction factor to allow for the effects of non-uniformity of cross-linking in the exchanger. From the plots of ln K[c] against the equivalent fraction exchanged values of o, the interaction energy associated with placing two B[z-] ions on adjacent sites, and K[T], the thermodynamic equilibrium constant and hence the standard free energy of exchange, DeltaG°, have been calculated. The standard enthalpies of exchange have been obtained both by an accurate calorimetric method and by application of the van't Hoff isochore. The good agreement shown between these two methods provides additional support for the theoretical approach. For some uni-univalent reactions, where data was available, linear correlations have been obtained between DeltaG°, the standard free energy of exchange, and S[ho], the partial molar entropy of hydration and, to a lesser extent, DeltaG°, the free energy of hydration of the ions. The selectivities for several univalent organic acid anions have been explained on the basis of interactions between the carbon chains and the external and exchanger aqueous phases and for some bivalent organic acid anions partly on the basis of the differences in charge separation. The interaction energy, o, is independent of temperature, but is dependent on external electrolyte concentration. It is also related to the water content of the exchanger and, more particularly, to the ratio of the water content divided by the crystal radius of the ion concerned. A method for predicting values of o and DeltaG° has been introduced and found to be useful in assessing the accuracy of the results obtained. The effect of changes in cross-linking on the foregoing phenomena has also been studied.

Complex networks of protein-ligand interactions underpin cellular function and communication. Disease can arise from disruption of these networks through the alteration of protein-ligand interaction affinities, for example by protein mutation or ligand modification. Understanding the mechanisms and principles that define affinity is therefore critical to both understanding and engineering biomolecular interactions, e.g. optimising drug molecules to interact effectively with their biomolecular targets. Thermodynamics reveals that affinity can be expressed in terms of the Gibbs free energy change upon interaction. In turn, this is composed of enthalpic and entropic terms, which can be thought of loosely as arising from structural and dynamic factors respectively. Though enthalpic terms can be estimated to a reasonable degree using structural data, a better understanding of entropic contributions from dynamic processes is required. The mouse major urinary protein (MUP) has been successfully established as a model system to investigate the thermodynamics of protein-ligand interactions. This work uses MUP, and employs a wide range of biophysical techniques, to develop our understanding of the dynamic factors in the thermodynamics of protein-ligand interactions. Four factors are addressed. Protein solvation is addressed by investigating proposed entropic solvation of the MUP binding pocket, and the possibility of engineering a new binding profile through manipulation of sidechains and solvation in the binding pocket. Ligand conformational entropy is addressed by performing the first systematic assessment of the widely predicted, yet inconsistently observed, benefits of removing and restricting ligand bonds. The greatest entropic loss upon binding, that of ligand rotational and translational entropy, is addressed by assessing MD predictions of significant residual translation and rotational motion of IBMP bound to MUP. This is achieved by using a combination of NMR techniques. Finally, protein dynamics are addressed by undertaking a preliminary investigation of a potentially promising novel technique for probing site-specific changes in protein dynamics upon ligand binding.

The current thesis presents a numerical study of steady and unsteady turbulent reacting flows. The flow is calculated using Finite Volume based parabolic and elliptic flow solvers. A transported probability density function (pdf) approach, closed at the joint-scalar level,is used for the inclusion of the thermochemistry. A common characteristic of all the studied cases are the strong finite rate chemistry effects which govern the flow. Two experimentally well documented turbulent lifted flames were computed in order to explore the detailed thermochemical flow structure and to reduce uncertainties associated with the chemical kinetics. The effect of the applied detailed chemistry and its subsequent simplification on the calculated thermochemical structure was also quantified. The two cases feature fuel jets of methane or hydrogen issuing into a vitiated, high temperature coflow. Molecular mixing is closed using the modified Curl's mixing model and two algebraic closures are considered for the closure of the mixing frequency. More complex flow patterns are considered through the calculation of bluff body stabilised flames. These flames feature a recirculation region and a neck zone of high strain rates, where significant levels of local extinction are found. The transported pdf method captures the local extinction and can predict the pollutant formation with high accuracy. The standard mixing frequency closure leads to over-prediction of local extinction, while an algebraic extension leads to improved predictions. When the flame is close to global extinction, strong instabilities occur, which lead to questions regarding the use of a two-dimensional approach. For this reason, a three-dimensional computational tool was developed and validated using both presumed and transported pdf methods for the representation of the thermochemistry.

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