Structure elucidation of charge delocalised carotenoid mono- and dications by NMR and VIS/NIR spectroscopy. Studies of the nucleophilic reactions of these cations. Studies of the β,β-carotene-iodine complex. Isolation and anmalysis of new carotenoid glucoside esters from extremophilic bacteria.

The research described in this thesis is directed toward the efficient, enantioselective synthesis of chiral products that have useful functionality. This goal was pursued through catalytic asymmetric hydrogenation, a reaction class that selectively introduces one or two stereocenters into a molecule in an atom-efficient step. This reaction uses a small amount (often <1 mol%) of a chiral catalyst to impart stereoselectivity to the product formed. Though catalytic asymmetric hydrogenation is not a new reaction type, there remain many substrate classes for which it is ineffective. The present thesis describes efforts to extend the reaction to some of these substrates classes. Some of the products synthesized in these studies may eventually find use as building blocks for the production of chiral pharmaceuticals, agrochemicals, or flavouring or colouring agents. However, the primary and immediate aim of this thesis was to develop and demonstrate new catalysts that are rapid and effective in the asymmetric hydrogenation of a broad range of compounds. Paper I describes the design and construction of two new, related chiral iridium compounds that are catalysts for asymmetric hydrogenation. They each contain an N,P-donating phosphinooxazoline ligand that is held together by a rigid bicyclic unit. One of these iridium compounds catalyzed the asymmetric hydrogenation of acyclic aryl imines, often with very good enantioselectivities. This is particularly notable because acyclic imines are difficult to reduce with useful enantioselectivity. The second catalyst was useful for the asymmetric hydrogenation of two aryl olefins. In Paper II, the class of catalysts introduced into Paper I is expanded to include many more related compounds, and these are also applied to the asymmetric hydrogenation of prochiral imines and olefins. By studying a range of related catalysts that differ in a single attribute, we were able to probe how different parts of the catalyst affect the yield and selectivity of the hydrogenation reactions. Whereas iridium catalysts had been applied to the asymmetric hydrogenation of imines and largely unfunctionalized olefins prior to this work (with varied degrees of success), they had not been used to reduce fluoroolefins. Their hydrogenation, which is discussed in Paper III, was complicated by concomitant defluorination to yield non-halogenated alkanes. To combat this problem, several iridium-based hydrogenation catalysts were applied to the reaction. Two catalysts stood out for their ability to produce chiral fluoroalkanes in good enantioselectivity while minimizing the defluorination reaction, and one of these bore a phosphinooxazoline ligand of the type described in Papers I and II. Enol phosphinates are another class of olefins that had not previously been subjected to iridium-catalyzed asymmetric hydrogenation. They do, however, constitute an attractive substrate class, because the product chiral alkyl phosphinates can be transformed into chiral alcohols or chiral phosphines with no erosion of enantiopurity. Iridium complexes of the phosphinooxazoline ligands described in Papers I and II were extremely effective catalysts for the asymmetric hydrogenation of enol phosphinates. They produced alkyl phosphinates from di- and trisubstituted enol phosphinate, β-ketoester-derived enol phosphinates, and even purely alkyl-substituted enol phopshinates, in very high yields and enantioselectivities.

Demands for zero greenhouse-gas emission vehicles have sharpened with today’s increased focus on global warming. Hydrogen storage is a key technology for the implementation of hydrogen powered vehicles. Metal hydrides can claim higher energy densities than alternative hydrogen storage materials, but a remaining challenge is to find a metal hydride which satisfies all current demands on practical usability. Several metals store large amounts of hydrogen by forming a metal hydride, e.g., Mg, Ti and Al. The main problems are the weight of the material and the reaction energy between the metal and hydrogen. Magnesium has a high storage capacity (7.6 wt.% hydrogen) in forming MgH2; this is a slow reaction, but can be accelerated either by minimizing the diffusion length within the hydride or by changing the diffusion properties. Light-metal hydrides have been studied in this thesis with the goal of finding new hydrogen storage compounds and of gaining a better understanding of the parameters which determine their storage properties. Various magnesium-containing compounds have been investigated. These systems represent different ways to address the problems which arise in exploiting magnesium based materials. The compounds were synthesized in sealed tantalum tubes, and investigated by in situ synchrotron radiation X-ray powder diffraction, neutron powder diffraction, isothermal measurements, thermal desorption spectroscopy and electron microscopy. It is demonstrated that hydrogen storage properties can be improved by alloying magnesium with yttrium or scandium. Mg-Y-compounds decompose in hydrogen to form MgH2 nano-structures. Hydrogen desorption kinetics are improved compared to pure MgH2. The influence of adding a third element, gallium or zinc has also been studied; it is shown that gallium improves hydrogen desorption from YH2. ScAl1-xMgx is presented here for the first time as a hydrogen storage material. It absorbs hydrogen by forming ScH2 and Al(Mg) in a fully reversible reaction. It is shown that the hydrogen desorption temperature of ScH2 is reduced by more than 400 °C by alloying with aluminium and magnesium.

Relaxation models are developed using numerical solutions of the Stochastic Liouville Equation of motion. Simplified descriptions such as the stochastic master equation is described in the context of fluorescence depolarisation experiments. Redfield theory is used in order to describe NMR relaxation in bicontinuous phases. The stochastic fluctuations in the relaxation models are accounted for using Brownian Dynamics simulation technique. A novel approach to quantitatively analyse fluorescence depolarisation experiments and to determine intramolecular distances is presented. A new Brownian Dynamics simulation technique is developed in order to characterize translational diffusion along the water lipid interface of bicontinuous cubic phases.

This thesis describes the synthesis and radiohalogenation of compounds of potential use for tumor targeting. The first section describes the synthesis and radioiodination of DNA intercalating compounds. The compounds are derivatives of 9-aminoacridine, and the anthracyclins daunorubicin and doxorubicin. The precursor compounds were labeled with 125I (T1/2 = 60 days), which is an Auger emitting nuclide. 125I decaying in the close vicinity of DNA is known to have a much higher cell killing effect than 125I decaying in the cytoplasm and some of the labeled compounds prepared in this thesis are currently being tested for use in targeted radionuclide therapy for cancer. The second section describes the radiobromination of closo-carboranes by subjecting the corresponding iodinated compounds to palladium-catalyzed halogen exchange using [76Br]bromide. The 76Br isotope (T1/2 = 16.2 h) is a positron emitting nuclide that is suitable for PET studies. Via the halogen exchange reaction good to excellent radiochemical yields of radiobrominated closo-carboranes were obtained. The results of the present study may prove to be applicable to pharmacokinetic studies of carboranes and their derivatives. The third and final section describes the indirect radiobromination of the trastuzumab anti-HER2 monoclonal antibody and of the anti-HER2 Affibody by means of an “one-pot” procedure using N-succinimidyl-5-(tributylstannyl)-3-pyridinecarboxylate (SPC) and ((4-hydroxyphenyl)ethyl))maleimide (HPEM), respectively. It was found that SPC and HPEM can be efficiently radiobrominated and thereafter coupled to the antibody and Affibody, respectively. The labeled proteins retained their capacity to bind specifically to HER2 expressing SKOV-3 cells in vitro. Application of this method to 76Br might enable the use of PET in the detection of HER2 expression in breast, ovarian, and urinary bladder carcinomas.

Polymer electrolytes are widely used as ion transport media in vital applications such as energy storage devices and electrochemical displays. To further develop these materials, it is important to understand their ionic conductivity mechanisms. It has long been thought that ionic conduction in a polymer electrolyte occurs in the amorphous phase, while the crystalline phase is insulating. However, this picture has recently been challenged by the discovery of the crystalline system LiXF6∙PEO6 (X=P, As or Sb) which exhibits higher conductivity than its amorphous counterpart. Their structures comprise interlocking hemi-helical PEO-chain pairs containing Li+ ions and separating them from the XF6- anions. The first Molecular Dynamics (MD) simulation study of the LiPF6∙PEO6 system is presented in this thesis. Although its conductivity is too low for most applications at ambient temperature, it can be enhanced by iso- and aliovalent anion doping. It is shown that the diffraction-determined structure is well reproduced on simulating the system using an infinite PEO-chain model. The Li-Oet coordination number here becomes 6 instead of 5; minor changes also occur in the polymer backbone configuration. The crystallographic asymmetric unit and diffraction profiles are also reproduced. On simulating a shorter-chain system (n=22), more resembling the real material, the structure retains its double hemi-helices, but the polymer adopts a more relaxed conformation, facilitating the formation of Li+-PF6- pairs. Infinite-chain simulation shows the ionic conduction to be dominated by anion motion, in contrast to earlier NMR results. The effects of doping are also reproduced. Shortening the polymer chain-length has the effect of raising the transport number for lithium, thereby bring it into better agreement with experiment. It can be concluded that it is critical to take polymer chain-length and chain-termination into account when modelling ionic conductivity mechanisms in crystalline polymer electrolytes.

Adsorption of organic molecules at a surface of titanium dioxide (101) anatase is studied using quantum-chemical density functional theory. Anatase can be used in solar cells. For the clean anatase surface the band gap is so large that only UV-light can excite electrons. Different groups with conjugated systems are attached to obtain a more suitable band gap. Phenol was attached in different positions to a cluster of anatase and geometry optimized using the B3LYP-functional. The geometry that was energetically most favorable was used to put in phenylmethanol, phenylethanol, naphthol, 2-phenanthrol, 1-pyrol and 2-perylol. To give a more realistic model of phenol at anatase, a study of a two- dimensional periodic anatase surface was also made. Molecular orbitals were calculated to study the overlap between HOMO and LUMO orbitals. The calculation shows that phenol will remain as a molecule and will not dissociate. The band gap gets smaller when molecules are attached at the cluster and with 2-perylol it reaches the energy of visible light. The molecular orbitals for HOMO, LUMO and LUMO of the adsorbed molecule were investigated. HOMO was localized at the molecule, LUMO at the cluster and LUMO of the adsorbed molecule move closer to the energy of LUMO when the number of rings increases.

No description available.

We have studied fundamental aspects of photo-induced dissociation kinetics and dynamics in several phenyl halides. By combining femtosecond pump-probe measurements with ab initio calculations we are able to account for several observations. In mixed phenyl halides, the dissociation kinetics is found to be dependent on the nature, the number, and the position of the substituents, and also on the excitation wavelength. A surprisingly large reduction in the dissociation time constant, compared to that of bromobenzene (~30 ps), is observed when having two or more fluorine atoms. For example, in bromopentafluorobenzene a subpicosecond time constant is obtained. This can be explained by a significant lowering of the repulsive potential energy curves (PEC) along the C-Br bond. However, several of the experimental results cannot be accounted for by one-dimensional PECs. Therefore, we suggest a refined model for the dissociation, in which the excited states of the same spin multiplicity are coupled by employing multidimensional potential energy surfaces. This model has been explicitly evaluated by quantum dynamics simulations in the case of 3-BrFPh, and it seems to be capable of capturing the main features in the measured kinetics. Thereby we are also able to clarify the role of spin-orbit coupling in these molecules.

In this thesis research on synthesis, microstructure and properties of carbide-based coatings is reported. These coatings are electrically conducting, and can be tailored for high hardness, low friction and wear, along with load-adaptive behaviour. Tailoring these properties is achieved by controlling the relative phase content of the material. Coatings have been synthesised by dc magnetron sputtering, and their structures have been characterised, mainly by X-ray photoelectron spectroscopy and X-ray diffraction. It has been shown that nanocomposites comprising of a nanocrystalline transition metal carbide (nc-MeCx, Me = Ti, Nb or V) and an amorphous carbon (a-C) matrix can result in low contact resistance in electrical contacts. Such materials also exhibit low friction and high resistance to wear, making them especially suitable for application in sliding contacts. The lowest contact resistance is attained for small amounts of the amorphous carbon phase. It has been shown that specific bonding structures are present in the interface between nc-TiCx and the a-C phases in the nanocomposite.  It was found in particular that Ti3d and C2p states are involved, and that considerable charge transfer occurs across the interface, thereby influencing the structure of the carbide. Further design possibilities were demonstrated for TiCx-based nanocomposites by alloying them with weakly carbide-forming metals, i.e., Me = Ni, Cu or Pt.  Metastable supersaturated solid solution carbides, (T1-xMex)Cy, were identified to result from this alloying process. The destabilisation of the TiCx-phase leads to changes in the phase distribution in the deposited nanocomposites, thus providing further control over the amount of carbon phase formed. Additional design possibilities became available through the decomposition of the metastable (Ti1-xMex)Cy phase through an appropriate choice of annealing conditions, yielding either more carbon phase or a new metallic phase involving Me. This alloying concept was also studied theoretically for all 3d transition metals using DFT techniques. It has also been demonstrated that Ar-ion etching (commonly used in the analysis of carbide based nanocomposites) can seriously influence the result of the analysis, especially for materials containing metastable phases. This implies that more sophisticated methods, or considerable care are needed in making these analyses, and that many of the earlier published results could well be in error.