Liquid chromatography-mass spectrometry (LC-MS) has become an important analytical on-line technique, capable of producing large amounts of data with high selectivity and sensitivity. Optimal use of the sophisticated instrumentation can be attained if the analytical chemists are guided to perform the proper experiments and to extract the useful information from the acquired data. In this thesis, strategies and methods concerning these two issues are presented. LC-MS method development will benefit from fundamental understanding of the processes involved. An experimental procedure was designed to determine the coefficients in a model for the electrospray process. By relating these coefficients to the experimental conditions, the influence on signal level and sensitivity for presence of matrix compounds was studied. For the optimization of LC-MS methods, strategies based on empirical modelling were worked out. Comparisons were made between artificial neural network (ANN) modelling and linear modelling tools, and a genetic algorithm was implemented to explore the ANN models. Visual interpretation and multivariate analysis of LC-MS data is hampered by background signals and noise, and a digital filter for background suppression and signal-to-noise improvement was developed. It is also important to indicate the presence of overlapping peaks, and a strategy for the assessment of peak purity was therefore worked out. These methods and several established methods were implemented in an add-on program (LC-MS Toolbox 1.0) for information extraction of LC-MS data. Ultimately, the data produced with LC-MS can be separated into the mass spectra, the elution profiles and the concentrations of the analytes, e.g. with PARAFAC modelling. The trilinear data structure assumed may, however, be distorted by variations in the LC conditions causing retention time shifts. An improved algorithm for time warping that can compensate for some of these deviations was worked out, and its performance as a pre-processing tool for PARAFAC was examined.

In this thesis the entropy production rate of diabatic distillation columns and a SO2 converter were minimised. This is the same as maximising the second law energy efficiency of the systems. The development of chemical industry can be made more sustainable by knowing this minimum. We found that the entropy production rate of distillation could be reduced up to 50%. In order to achieve this reduction, heat exchangers were added on each tray. The characteristics of an optimum distillation column were presented. Furthermore, the entropy production rate of a SO2 converter was reduced with 16.7% by altering the heights of catalytic beds, transfer areas of heat exchangers, and temperature differences over heat exchangers. These reductions show that there is still a large improvement potential in chemical industry. By applying the improved operations the world oil production can be reduced in the order of magnitude of 1%. A similar reduction in the emission of the greenhouse gas CO2 can be expected. For deriving the entropy production rate in a systematic manner the theory of irreversible thermodynamics was useful. A simpler and a more complicated equation for the entropy production rate of distillation were derived. The simpler equation used only one force-flux product. It was suitable for minimisation of the entropy production rate of columns with the assumption of equilibrium between the outlets on each tray. The more complicated equation was able to describe satisfactorily the entropy production rate of an experimental column that separated the non-ideal mixture water-ethanol. It was next used to derive an extended set of transport equations for distillation, that includes the interface and the Soret effect (or thermal diffusion). Finally, irreversible thermodynamics was used to describe the contributions to the entropy production rate of heat transfer in heat exchangers. This contribution had a significant impact on the results of the minimisations. A method that can provide the chemical industry the thermodynamically optimum operation of distillation columns and reactors was constructed and exemplified. Once the system and its boundaries are determined, the objective function with its constraints and variables are set up. Several suitable minimisation procedures exist. Finally, the design of the thermodynamically optimum system is obtained from the state of minimum entropy production rate.

Enantiomerically pure amines and alcohols are particularly important synthons for the preparation of pharmaceuticals and agrochemicals. Notwithstanding the advances that have been achieved in asymmetric synthesis, resolution of racemates is probably the most current approach for the preparation of pure enantiomers. On the other hand, resolution processes suffer from disadvantages of low yields caused by the loss of at least 50% of the undesired isomer. Among the attractive methods for avoiding the drawbacks of resolution processes is inversion of configuration of the unwanted isomer. Although there are several existing methodologies for inversion and stereoselective transformations of chiral alcohols, corresponding methods for inversion of chiral amines has received less attention. The main objective of the project “Stereoselective transformations of chiral amines” was therefore to develop effective methods for inversion and stereoselective transformations of chiral amines. This thesis discuss the utility of three nucleophilic substitution methods in stereoselective transformations of chiral amines. The first investigation towards this goal was carried out using cyclic aryldisulfonylimide leaving group. Substitution of a chiral amine via N,Nnaphthalene- 1,2-disulfonylimide intermediate gave azide and alcohol products with 60-73% inversion of configuration, which was 20-25% lower compared to the previously studied relative disulfonylimides. Displacement of this group using aroxide anions afforded chiral aryl ethers with 70-87% inversion of stereochemistry. Chiral analysis of the ether products required synthesis of authentic reference compounds. This was achieved via benzyne route and by nucleophilic substitution on the derivatives of chiral alcohols. The benzyne route gave chiral phenyl ether from enantiopure alcohols with complete retention of configuration while the trifluoroacetate derivatives of chiral alcohols produced chiral aryl ethers with complete inversion of stereochemistry. The 2,4,6-triphenylpyridinium cations were the next intermediates investigated in this study. These derivatives were synthesized from 2,4,6-triphenylpyrylium tetrafluoroborate in 84-90% yields using procedures described by Katritzky. Nucleophilic substitution on pyridinium salts of aliphatic chiral amines using azide and hydroxide anions gave products with 96 to 100% inversion of configuration. The utility of diazonium salts for inversion of chiral amines was also investigated in the present study. This method was only focused on stereoselective transformations of α-amino acids as diazotization-dediazoniation of other aliphatic amines is of little interest for organic synthesis. Diazotization of L-alanine and L-phenylalanine ethyl esters hydrochlorides using alkyl nitrites in aprotic solvents, in the presence of azide anion, yielded optically active chloro substituents as the only products, instead of the intended azide compounds. Attempts to avoid counterion substitution by using ammonium tosylate to replace the ammonium chlorides was not useful and a tosyl product was isolated instead. Proposals to rectify this problem have been suggested. These include the use of much more inert counterions such as tetrafluoroborate or replacing the hydrochlorides with hydroazides. An alternative which could deliver the nucleophile in an intramolecular fashion has also been postulated. Investigations of these hypotheses are currently conducted. Parallel to diazotization reactions was an investigation on inversion of α-amino acids via N,N-disulfonylimides and 2,4,6-triphenylpyridinium cation leaving groups. Studies with N,N-disulfonylimide derivatives showed that this leaving group is not useful for inversion of α-amino acids. Nucleophilic substitution on the 2,4,6-triphenylpyridinium salts of amino acids afforded partial racemized substitution products. The drawback in the utility of the pyridinium salts has been identified and efforts are underway to remove this impediment.

<p>Ozone is used in many applications in the industry as an oxidising agent for example for bleaching and sterilisation. The decomposition of ozone in aqueous solutions is complex, and is affected by many properties such as, pH, temperature and substances present in the water. Additives can either accelerate the decomposition rate of ozone or have a stabilising effect of the ozone decay. By controlling the decomposition of ozone it is possible to increase the oxidative capacity of ozone.</p><p>In this work the chemistry of acidic aqueous ozone is studied and ways to stabilise the decomposition of ozone in such solutions. The main work emphasizes the possibility to use surfactants in order to develop a new type of cleaning systems for the sterilisation of medical equipment.</p>

<p>This licentiate thesis comprises two parallel studies dealing with water-based flexographic inks on PE-coated liquid packaging board. The commercial waterbased inks that were used in both studies vary in type of pigment and acrylatepolymer vehicle, and in pigment/vehicle mixing proportions. One vehicle is solely based on emulsion polymer, another contains solution polymer, and the third is a 50/50 blend of these two. The first study presents results from characterisation of a matrix of these water-based inks with respect to their rheology, surface tension and wetting of PE-coated board. The rheological properties were measured over a wide range of shear rates relevant to various stages in the printing process. All inks represent shear thinning fluids, forming thixotropic structures. The plastic viscosity and yield stress are shown to increase strongly with content of solution polymers (at comparable solids contents). Measurements of static surface tension and drop spreading, on untreated as well as corona treated board, clearly display differences in interfacial properties for the vehicles. An increasing amount of solution polymer give lower surface tension values, while the equilibrium contact angles increase. The validity of a simple model for expressing the ink drop spreading dynamics was tested and could be applied to spreading on treated board. The rheology, surface tension and wetting properties are also shown to depend on the pigment type (cyan or black) in the ink and on the pigment/vehicle mixing proportion.</p><p>In the second study, the print performance of this matrix of inks on the PE-coated board was evaluated. Changes in the ink formulation are shown to have significant influence on the ink amount transferred to the board and the print quality parameters. The 50/50 intermediate vehicle consistently gave the highest ink amounts, although the highest print density generally was obtained with the vehicle containing most solution polymer. High contents of solution polymer also resulted in more uniform prints and high print gloss. Mottling was most severe with the vehicle containing solely emulsion polymers. The transferred wet ink amount is demonstrated to correlate well with the plastic viscosity and static surface tension of the ink.</p>

<p>A technique to alter the morphology of the inner surface of fused silica capillaries has been developed. The internal surface area is enlarged by means of nano-wires of silica, which are grown from the capillary walls. The growth is initiated by the decomposition of the etchant precursor 2-chloro-1,1,2–trifluoroethylmethyl ether at elevated temperature and pressure. It is suggested that the formation of the nano-wires is a process where hydrogen fluoride is continuously consumed and re-liberated. The amorphous bulk silica wall is dissolved, vaporized and finally condensed, yielding a directional re-formation of silica into nano-wire structures. The unidirectional growth of the nano-wires seems to follow the well-known vapor-liquid-solid (VLS) mechanism since characteristic attributes of the VLS mechanism can be observed in the modified capillaries, such as spherical particles terminating each nano-wire. An alternative procedure was developed based on non-isothermal etching which enabled nano-wire outgrowth in fused silica capillaries with internal diameters exceeding 5 µm. The etched and modified capillaries are expected to be suitable for fluidic applications where a higher surface-to-volume ratio is beneficial, such as open tubular liquid chromatography as well as solid-phase micro-reactors and catalysis including enzymatic reactions. </p><p>The last part of the thesis describes new techniques developed for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. A set of novel matrices based on polymers/oligomers of benzodioxins and thiophenes has been introduced. Using this approach, which has been given the name Polymer-Assisted Laser Desorption/Ionization (PALDI), the low m/z-range of the mass spectrum, from 180 to 1.000 Da, could be used without the abundant chemical noise which normally disturbs such MALDI-MS spectra. Some of the PALDI matrices also showed excellent behavior in the analysis of low molecular weight polymers. A methodology based on non-linear regression of cumulative frequency distributions in polymers has been developed to compare and evaluate different matrix/polymer/cation agent sample combinations for MALDI and PALDl-MS analyses of low molecular weight polymers. </p>

Molecular mimics of PS II, which consist of a photosensitizer linked to electron acceptors/donors, are attractive candidates for the conversion of solar energy into chemical energy. Several different classes of sensitizers have been studied and among these, ruthenium(II) polypyridyl complexes continue to attract major attention. The first part of this thesis presents the photophysical properties, stereochemistry, and general synthesis of ruthenium(II) polypyridyl complexes based on 2,2´-bipyridyl and 2,2´:6´,2´´-terpyridyl ligands. The second part deals with ruthenium(II) polypyridyl complexes linked to electron acceptors (benzoquinone, naphthalene diimide) and electron donors (phenothiazine, tyrosine, manganese complexes). Functionalized 2,2´-bipyridines and 2,2´:6´,2´´-terpyridines were synthesized and used in the stepwise assembly of the chromophore-quencher complexes. These were fully characterized and the redox properties were studied by cyclic and differential pulse voltammetry. The intramolecular charge-separated states formed after light excitation of the ruthenium(II) unit were observed by time-resolved absorption and EPR spectroscopy. In the third part of this thesis, the synthesis and photophysical properties of a novel class of bistridentate ruthenium(II) polypyridyl complexes based on bipyridyl-pyridyl methane ligamds are discussed. The solution structures of the homoleptic and heteroleptic complexes were studied by 2D NMR techniques. The X-ray structure of one of the homoleptic complexes has been solved. The effect on the excited state lifetime for these ruthenium(II) complexes compared to the parent [Ru(tpy)2]2+ is discussed. Finally, in one of the heteroleptic complexes an interesting reversible linkage iomerization was observed that could be induced either electrochemically or chemically.

Diss. (sammanfattning) Linköping : Univ., 2004. / Härtill 6 uppsatser.

<p>In this thesis, quantum chemical methods have been used to shed light on the reaction mechanisms of several dinuclear zinc enzymes. The enzymes studied are involved in the hydrolysis of phosphates, amides, and carboxylic esters, namely RNase Z, Dihydroorotase (DHO), and N-acyl homoserine lactone hydrolase (AHL lactonase). The density functional method B3LYP, together with quite large active site models, was used to investigate these enzymatic reactions. Several plausible proposed mechanisms, involving protonation states of important active site residues (DHO), substrate orientations (AHL lactonase), have been considered. The calculated energetics can be used to assess the feasibility of the suggested reaction mechanisms. Based on the calculations and also on other related dinuclear zinc enzymes studied previously, some general mechanistic features have been uncovered.</p><p>For all three enzymes, the nucleophilicity of the bridging hydroxide is shown to be sufficient to perform the nucleophilic attack on the substrates. During the attack, the negative charge is transferred from the bridging hydroxide to the substrate oxygen (P=O or C=O). For phosphate hydrolysis, an in line attack have been suggested for RNase Z. In addition, the two zinc ions in RNase Z are directly involved in stabilizing the negative charge in the penta-coordinated transition states. For carbonyl substrates, only one zinc ion participates in the oxygen anion stabilization in the transition states and the tetrahedral intermediates. Furthermore, the enzymes always use the zinc ion with less negatively-charged ligands to play such role.</p><p>All the substrates investigated have poor leaving groups. Therefore, either the zinc ions or some active site residues help the cleavage of the scissile bond. For RNase Z, a Glu-His diad was suggested to protonate the leaving group. For DHO, an Asp residue was shown to transfer a proton from the bridging hydroxide to the leaving group nitrogen. For AHL lactonase, a zinc ion was also observed to stabilize the leaving oxygen anion.</p>

<p>The present thesis deals with the investigation of some perovskite related complex cobaltates. The phases Sr₂Co_2-xGa_xO₅ (0.3 ≤ x ≤ 0.7), Sr₂Co_2-xAl_xO₅ (0.3 ≤ x ≤ 0.5), Sr_1-xBi_xCoO_3-y (0.1 ≤ x ≤ 0.2), Sr_0.75Y_0.25Co_1-xGaxO_2.625 (0.125 ≤ x ≤ 0.375) and Sr_0.75Y_0.25Co_1-xFexO_2.625+δ (0.125 ≤ x ≤ 0.625) were synthesised and characterised. All these compounds crystallises with similar structures, they are all composed by altering layers of octahedra and tetrahedra although in the two former, the tetrahedra are organised in chains (the Brownmillerite structure), while in the latter three the tetrahedra arranges as segregated Co₄O₁₂units (the 314 type structure). The techniques X-ray and neutron diffraction, transmission electron microscopy, thermal analysis and magnetic measurements were used to track structural and important physical properties.</p>