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There is great interest within the physics and chemistry communities in the properties of ultracold molecules. Electromagnetic fields can be used to create, trap, and modify the collisional dynamics of ultracold molecules, and thus the properties of ultracold molecules in electromagnetic fields is of growing importance. This thesis examines some of the effects of externally applied electromagnetic fields on ultracold molecules. Initially, magnetic Feshbach resonances in combined electric and magnetic fields are examined in the collisions of He($^1S$)+SO($^3\Sigma^-$). Through detailed quantum scattering calculations, it is then shown that the sympathetic cooling of NH($^3\Sigma^-$) molecules with Mg atoms has a good prospect of success, a first for a neutral molecular system. Detailed quantum scattering calculations are performed for a wide range of collision energies and magnetic field strengths and it is found that the ratio of elastic to inelastic collisions is large for temperatures below 10 mK, and increases as the collision energy and magnetic field strength decrease. The near threshold collision properties of Mg+NH have been examined using a multichannel quantum defect theory approach. A new type of conical intersection, that is a function of applied electromagnetic fields only, is also demonstrated. For states of opposite parity, brought into degeneracy with a magnetic field, the degeneracy can be resolved by the addition of an electric field, forming a conical intersection. A suitable arrangement of fields could thus be used to create a conical intersection in laboratory coordinates within an ultracold trapped gas. For a Bose-Einstein condensate, in the mean-field approximation, the resultant geometric phase effect induces stable states of persistent superfluid flow that are characterized by half-integer quantized angular momentum.

A series of 14-crown-4 derivatives bearing amide substituents have been prepared in order to develop ionophores selective for lithium. Complexation with lithium ions was monitored using ( 13)C and IR spectroscopy and liquid membrane electrodes prepared and evaluated using a fixed interference method. The highest selectivities with respect to sodium ions were obtained for di-n-butylamide-oNPOE and a di-n-benzylamide-oNPOE derivatives; log( POT)(_ Li,Na) = -2.92 and -2.93 respectively. A series of amide and amide-ester N-functionalised coronands based upon [12]-N202 , [15]-N203 and [18]-N204 parent macrocycles has been prepared. Complexation of certain alkali and alkaline-earth cations was monitored by ( 13)C NMR and IR specteoscopy, enthalpies of complexation measured in methanolic solution using micro-calorimetry and stability constants measured in aqueous media by potentiometric methods. Strong complexation of Ca2+ in aqueous media was observed with good selectivity over Na+ and K+. Lower free energies of binding for Ha cations were displayed by the tertiary amide derivative (of [12]N(_2)O(_2)), than by its secondary analogue, despite displaying higher enthalpies of complexation. Thus the lower free energies result from significantly lower entropies of complexation. Two sets of oxa-amide and oxa-ester tripodal ligands have been prepared and solvent membranes fabricated. The effects of the nature of the plasticiser, bis (butylpentyl)adipate (BBPA) verses o -nitrophenyl octyl ether (oNPOE), the ligand structure and the ionic strength of the analyte solution on the electrode response to la and Ila cations were studied. The performance of the oxa-amides was superior to that of the oxa-esters particularly at higher ionic strengths, however super-Nernstian responses were observed with the more charge-dense ions in the presence of chloride and/or with the less polar plasticiser BBPA. Measurements of intracellular sodium concentration could be effected with a sensor based upon bis (N,N',N"-tributyl)-4,4',4"-propylidintris(3-oxabutanamide) and oNPOE for which -log KPOT = 2.64 and -log KPOT =3.0, whilst bis (N,N',N"-tributyl)Na,K Na,Mg-2,2',2"-phenylmethylidintris(3-oxabutamide) and oNPOE functioned as a calcium sensor, displaying excellent selectivity over Mg. -log KPOT= 4.3.Ca,MgAdditionally a triamide based upon a cyclohexane triol skeleton was prepared, a membrane fabricated and its performance assessed as a sodium sensor.

This thesis is concerned with the thermal treatment of lignocellulosic biomass using ionic liquids for the purpose of comminution via dissolution, for fractionating the biological composite and for obtaining aqueous solutions of carbohydrate monomers from the pulp via enzymatic hydrolysis. A major focus was the relationship between the choice of the anion and the effectiveness of the treatment. The synthesis of a range of 1-butyl-3-methylimidazolium ionic liquids with strongly hydrogen-bond basic anions was accomplished. Selected, process-relevant physicochemical properties were measured, such as the Kamlet-Taft solvent polarity, hygroscopicity and thermal stability. It was shown that 1-butyl-3-methylimidazolium acetate is not stable at 120°C, while other ionic liquids e.g. 1-butyl-3-methylimidazolium hydrogen sulfate exhibit very good long-term thermal stability. It was shown that hydrogen-bond basic 1-butyl-3-methylimidazolium ionic liquids attract more than stoichiometric quantities of water when exposed to air, suggesting that ionic liquid pretreatment under anhydrous conditions is difficult to achieve. Dissolution of air-dried wood chips in 1-butyl-3-methylimidazolium ionic liquids was attempted. It was shown that the large particle size and the moisture contained in the biomass hamper complete dissolution. The hydrogen-bond basicity of the ionic liquid, described by the Kamlet-Taft parameter ß, was correlated with the ability to expand as well as partially and anisotropically dissolve wood chips. Pretreatment of lignocellulosic biomass with 1-butyl-3- methylimidazolium methyl sulfate, 1-butyl-3-methylimidazolium hydrogen sulfate and 1-butyl-3-methylimidazolium methanesulfonate was explored and high saccharification yields were reported. It was found that successful application of methyl sulfate and hydrogen sulfate ionic liquids requires addition of water and that comparatively high water contents are tolerated. Fractionation of lignocellulose into an insoluble cellulose fraction, a solubilised hemicellulose fraction and a lignin containing precipitate was achieved. The influence of water content, pretreatment time and biomass type on the enzymatic saccharification yield and the extent of hemicellulose solubilisation, hydrolysis and dehydration were examined.

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