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  • 1.
    Abbrent, Sabina
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Lithium ion interactions in polymer gel electrolytes: Effect on structure, dynamics and morphology2000Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Polymer electrolytes are an essential part of the modern all-solid lithium battery. Several properties, such as mechanical and thermal stability, good ionic conductivity and compatibility with other materials used in the battery are necessary for a successful material.

    This thesis is focused on the ionic interactions in two electrolyte systems, based on a cross-linked polyethylene oxide (nona(ethylene oxide)dimethacrylate) or a fluorinated copolymer (polyvinylidene fluoride-hexafluoropropylene). Changes of thermal properties and morphology of and coordination in the electrolyte on addition of a lithium salt (LiTFSI) and different types and concentrations of solvents are studied. These properties are shown to control the ionic conductivity of the resulting material, influencing the conductivity mechanism.

    The presumably inert polyvinylidene fluoride is shown to undergo large structural changes, where polar conformations of the polymer backbone appear on salt addition, inducing a different crystalline phase. The lithium cation in the polyethylene oxide based electrolyte can coordinate either to the polymer chain or to the solvent. In for example systems containing propylene carbonate, the lithium ion binds more strongly to the polymer than to the solvent. This is in contrast to the systems with dimethyl sulphoxide where the ion prefers the solvent. This variation in coordination also strongly affects the mobility of the cation, reflected both in diffusion constants and in conductivity data.

    A combination of techniques was necessary to use for a deeper understanding of these complex materials. Coordination has been studied by FTIR and high resolution NMR, dynamics by NMR diffusion measurements and impedance spectroscopy, and morphology by diffraction techniques and DSC.

  • 2.
    Aggeryd, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    Bestämning av Substitutionsgraden hos Natrium-karboxymetylcellulosa, CMC: En tillämpning av den utvidgade Henderson-Hasselbalchs ekvation och simplex-optimering för bestämning av ekvivalensvolymer vid potentiometrisk titrering1984Licentiate thesis, monograph (Other academic)
  • 3.
    Alexander, James N.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Novel detection schemes and high resolution separations in microcolumn liquid separations1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Three micro detectors were developed and studied using micro-liquidchromatography (micro-LC). An evaporative light scattering detector (ELSD) nebulizer was developed for use with flow rates ranging from 0.5 to 10 µL/min. The parameters that affect analyte response were investigated and the most influential were capillary tip position and nebulization gas flow rate. One unique advantage of thismicro detector is that it can be operated at ambient conditions which allows for the analysis of semi-volatile compounds.

    A radio activity monitor (RAM) flow cell was developed for use at 3 µL/min and was designed for coupling to mass spectrometry (MS). The parameters that affect analyte response and band broadening were studied. Reducing the solid scintillant particle size to 9 µm and efficiently packing the solid cells allowed for direct coupling to MS without compromising the chromatographic separation.

    A nano-electrospray ionization (BSI) source for MS was developed and coupled to nano-LC and capillary electrophoresis (CE). This source incorporated a 50 µm i.d. stainless steel tip that was coupled to the separation capillary. At flow rates of 100 nL/min a stable electrospray was achieved.

    A multi-use separations system was developed for isocratic and gradient elution micro-LC, capillary electrochromatography (CEC), and pressure CEC (PEC). The details of the system and studies on peak area and retention time repeatability are reported. Comparisons are made between nano-LC and CEC. On average, column efficiency is 57% greater for CEC compared to nano-LC using the same nanocolumn.

  • 4.
    Alfredsson, Maria
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Polar molecules in crystalline and surface environments: From first principles1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    With the knowledge of the composition and structure of a chemical system, be it a molecule, a two-dimensional surface or a three-dimensional crystal, it is now possible to predict the specific properties of the compound under consideration via computational studies. Molecular and periodic Hartree-Fock and DFT calculations have been used as a tool to study polar molecules and how their properties respond to the molecular environment in a crystal or on an ionic surface. The investigation covers a range of molecules (HF, HC1, HCN, H2O, OH-, OH., N2, CO and LiF) with different net charges, dipole moments and polarisibility, and a range of crystals and crystalline surfaces: hydrogen-bonded, ionic and ferroelectric.

    The step-wise build up of the molecular properties (geometries, energies, dipole moments, vibrational frequencies etc.) has been investigated. It was found that sorne molecular properties converge quickly towards the crystal value, others more slowly. Molecules adsorbed on a solid surface were studied as a function of adsorptionenergy, substrate and surface coverage. For the ionic surfaces studied here it was found that the properties of the chemi- and physisorbed molecules are as sensitive to the surface coverage as to the adsorption of the ad-molecule to the surface. The vibrational frequency shift of the ad-molecule has been given special attention.

    Finally the spontaneous polarisation in two ferroelectric crystals was calculated within the Berry-phase approach.

  • 5.
    Amirkhani, Ardeshir
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Development of Techniques and Methods for the Quantitative Analysis of Endogenous Substances by Microcolumn Liquid Chromatography Coupled to Mass Spectrometry2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Liquid chromatography-mass spectrometry (LC-MS) is a powerful technique for the analysis of endogenous compounds. The introduction of electrospray ionization (ESI) as an interface between LC and MS has contributed strongly to a trend towards miniaturization of LC, due to the possibility to perform ESI at low flow rates. In this thesis, several aspects regarding the design of miniaturized LC systems and electrospray emitters were investigated. In addition miniaturized LC-ESI-MS have been used for the qualitative and quantitative analysis of endogenous polar compounds, peptides and protein digests.

    The performance of miniaturized LC-MS was compared using different electrospray emitter configurations. The results indicated that the efficiency of the LC system is rather independent of the configuration of the emitter.

    The lifetime of gold-coated fused silica electrospray emitters based on vapor deposited adhesion layers of titanium were investigated. The long lifetime of the emitter facilitates the use in LC-MS experiments, exemplified LC-MS by analysis of neuropeptides.

    The ESI voltage is shown to interfere with liquid chromatographic separations performed in packed porous graphitic carbon capillary column. This interference is ascribed to the presence of an electric field over the conductive column in absence of a ground point between the column and the ESI emitter.

    The solid supported enhanced microdialysis for analysis of neuropeptides were compared with conventional microdialysis. The difference between the two methodologies were evaluated by LC-MS analysis of the microdialysates. The solid supported method gave in general higher relative recoveries.

    Finally, a method of standard addition was developed to determine total level of tryptophan and two of its metabolites in human plasma by capillary LC-ESI tandem mass spectrometry. The method was applied in a clinical study of multiple scleroses patients treated with cytokines (IFN Beta 1a, 1b). The results show that the intervention effects the tryptophan metabolism.

    List of papers
    1. Comparison between different sheathless electrospray emitter configurations regarding the performance of nanoscale liquid chromatography time-of-flight mass spectrometry analysis
    Open this publication in new window or tab >>Comparison between different sheathless electrospray emitter configurations regarding the performance of nanoscale liquid chromatography time-of-flight mass spectrometry analysis
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    2004 (English)In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1033, no 2, p. 257-266Article in journal (Refereed) Published
    Abstract [en]

    Four different sheathless electrospray ionization (ESI) configurations were investigated for a nano liquid chromatography (LC) system. The studied configurations were: a column with an integrated emitter, with the ESI potential applied before or after the column, and a column with separate emitter, with the ESI voltage applied at a union before the emitter or at the emitter tip. The results indicates that the efficiency of the LC system is rather independent of the configuration when using 95 μm i.d. columns, acetic mobile phase and standard peptides as a sample. Introduction of post column dead volume seems not to be a critical issue at least with flow rates down to 600 nl/min.

    Keywords
    Electrospray ionization, Band broadening, Principal component analysis, Instrumentation, Peptides
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-91889 (URN)10.1016/j.chroma.2004.01.063 (DOI)
    Available from: 2004-05-25 Created: 2004-05-25 Last updated: 2017-12-14Bibliographically approved
    2. Gold-coated fused-silica sheathless electrospray emitters based on vapor-deposited titanium adhesion layers
    Open this publication in new window or tab >>Gold-coated fused-silica sheathless electrospray emitters based on vapor-deposited titanium adhesion layers
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    2003 In: Rapid Communication Mass Spectrometry, Vol. 17, no 14, p. 1535-1540Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-91337 (URN)
    Available from: 2004-01-30 Created: 2004-01-30Bibliographically approved
    3. Interference of the electrospray voltage on chromatographic separations using porous graphitic carbon columns
    Open this publication in new window or tab >>Interference of the electrospray voltage on chromatographic separations using porous graphitic carbon columns
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    2004 (English)In: Journal of Mass Spectrometry, ISSN 1076-5174, E-ISSN 1096-9888, Vol. 39, no 2, p. 216-222Article in journal (Refereed) Published
    Abstract [en]

    The electrospray ionization (ESI) voltage is shown to interfere with liquid chromatographic separations performed with packed porous graphitic carbon (PGC) capillary columns. This interference is ascribed to the presence of an electric field over the conductive column in the absence of an earth point between the column and the ESI emitter. The current evolved alters the chromatographic behavior of the catecholamine metabolite 3-O-methyl-DOPA significantly, as both peak splitting and a dramatic decrease in the retention time were observed. Furthermore, the response from the mass spectrometer was decreased by 33% at the same time. A related compound, tyrosine, exhibited decreased retention times but no peak splitting, whereas no shifts in the retention times (or peak splitting) were seen for the less retained dopamine and noradrenaline. When the current through the PGC column was eliminated by the use of an earth point between the column and the ESI emitter, the chromatographic behavior of the column was found to return slowly to normal after hours of equilibration with 60 : 40 (v/v) methanol-ammonium formate buffer of pH 2.9. The behavior of the PGC column with and without the earth point was found to be highly reproducible during a period of 1 month. We propose that the effect of the ESI voltage on the chromatographic behavior of the PGC column is due to associated redox reactions affecting both the PGC particles and the analytes. It is concluded that (for analytical reasons), care should be taken to ensure that no current is flowing through the chromatographic system when interfacing PGC columns, and conducting parts in general, to ESI mass spectrometry.

    Keywords
    catecholamine, dopamine, electrochemistry, porous graphitic carbon, electrospray, mass spectrometry, liquid chromatography
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-91888 (URN)10.1002/jms.589 (DOI)
    Available from: 2004-05-25 Created: 2004-05-25 Last updated: 2017-12-14Bibliographically approved
    4. A feasibility study of solid supported enhanced microdialysis
    Open this publication in new window or tab >>A feasibility study of solid supported enhanced microdialysis
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    2004 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 76, no 6, p. 1678-1682Article in journal (Refereed) Published
    Abstract [en]

    For the first time, a solid supported enhanced microdialysis methodology for analysis of neuropeptides is described. The microdialysis samples were, in this study, subsequently collected in fractions, dissolved from the solid particles, dried, and resolved in a formic acid buffer in order to make them suitable for capillary liquid chromatography-mass spectrometry. Different microdialysis flow profiles were evaluated where air-gapped continuous flow was considered most suitable for the solid supported microdialysis mode. Six endogenous neuropeptides were initially used to investigate the feasibility of this enhanced microdialysis methodology. The improved relative recovery obtained from the solid supported enhanced microdialysis was varying from no effect to 10 times higher as compared to ordinary microdialysis. The most efficient enrichment was obtained for luteinizing hormone releasing hormone, which was the largest but also the most hydrophilic of the peptides. In contrast, no significant difference in recovery was observed for Leu-enkephalin being the smallest and the most hydrophobic peptide tested. These results indicate an increased flux and selective uptake of hydrophilic peptides across the membrane and enrichment on the particles in solid supported microdialysis.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-93181 (URN)10.1021/ac035305l (DOI)15018567 (PubMedID)
    Available from: 2005-05-10 Created: 2005-05-10 Last updated: 2017-12-14Bibliographically approved
    5. Quantitation of tryptophan, kynurenine and kynurenic acid in human plasma by capillary liquid chromatography - electrospray
    Open this publication in new window or tab >>Quantitation of tryptophan, kynurenine and kynurenic acid in human plasma by capillary liquid chromatography - electrospray
    2002 In: Journal of Chromatography B, Vol. 780, no 2, p. 381-387Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-91340 (URN)
    Available from: 2004-01-30 Created: 2004-01-30 Last updated: 2011-03-21
    6. Beta-interferon effects the tryptophan metabolism in the plasma of multiple sclerosis patients
    Open this publication in new window or tab >>Beta-interferon effects the tryptophan metabolism in the plasma of multiple sclerosis patients
    Show others...
    Manuscript (Other academic)
    Identifiers
    urn:nbn:se:uu:diva-91341 (URN)
    Available from: 2004-01-30 Created: 2004-01-30 Last updated: 2011-03-21
  • 6.
    Amirkhani, Ardeshir
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Rajda, Cecilia
    Arvidsson, Björn
    Bencsik, Krisztina
    Boda, Krisztina
    Seres, Erika
    Markides, Karin E.
    Vecsei, Laszlo
    Bergquist, Jonas
    Beta-interferon effects the tryptophan metabolism in the plasma of multiple sclerosis patientsManuscript (Other academic)
  • 7.
    Andersson, Anna S.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Lithium iron phosphates as cathode materials in lithium batteries2000Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Iron-based oxides are perhaps the only realistic cathode materials for electric and electric-hybrid vehicle applications. Two types of lithium iron phosphate, LiFePO4 andR-Li3Fe2(PO4)3, have been investigated for use within the lithium/lithium-ion polymer batteryconcept. The main techniques exploited have been: electrochemical cycling; X-ray andneutron diffraction - to study structural changes of the host material during lithiuminsertion/extraction; Mössbauer spectroscopy - to probe changes in the local structure of theFe atoms.

    Lithium extraction/insertion for LiFePO4, (olivine-type structure) has been followed by acombination of in situ X-ray diffraction and in situ Mössbauer spectroscopy. QuantitativeRietveld analysis of diffraction data has given good agreement with electrochemical andMössbauer spectroscopy data: ca. 20% of the LiFePO4 phase remains after charging. Possiblemechanisms to describe the capacity loss are proposed. High-temperature cycling (at 40oC and60oC) has shown the specific capacity to be markedly enhanced at higher temperatures.

    In situ Mössbauer spectroscopy has also been used to study the insertion of lithium into R-Li3Fe2(PO4)3. The two non-equivalent Fe3+ ions cannot be distinguished, whereas two typesof Fe2+ site appear on lithium insertion. Lithium appears to enter a site closer to one of theFe atoms. Elevated-temperature cycling shows the temperature dependence of R-Li3Fe2(PO4)3to be less marked than for the LiFePO4 system.

    The magnetic properties of R-Li3Fe2(PO4)3 have been investigated for the first time: a para- to antiferromagnetic transition is seen at 28 ~ K. Neutron powder diffraction shows that the Fe magnetic dipoles lie close to the ab-plane and are ferromagnetically aligned within an Fesheet perpendicular to the c-axis, but are antiferromagnetically coupled to adjacent sheets.

  • 8.
    Andersson, Mikael
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Analytisk kemi.
    Characterisation of the chemical and functional stability of chromatography media2000Licentiate thesis, monograph (Other scientific)
  • 9.
    Andersson, Örjan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Two Modified 2,3-Diamino-naphthalenes for Spectro-fluorimetric Determination of Selenium in Biological Samples1995Licentiate thesis, monograph (Other academic)
  • 10.
    Antoni, Gunnar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    Omura, H
    Ikemoto, M
    Moulder, R
    Watanabe, Y
    Långström, B
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Enzyme catalysed synthesis of L-(4-11C) aspartate and L-(5-11C) glutamate2001In: J. Labbelled Compd. Radiopharm.Article in journal (Other academic)
  • 11.
    Aranyos, Viviane
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Dyes and their adsorption onto nanocrystalline TiO2 electrodes: Synthesis, characterisation and applications2000Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The syntheses of two type of dyes (phthalocyanine and ruthenium tris-bipyridyl) are presented here. Their characterisation involves the use of cyclic voltammetry, NMR- and UV-visible spectroscopy. Once adsorbed on nanocrystalline TiO2 electrodes, their electrochemical, spectroelectrochemical and photoelectrochemical properties were investigated.

    In the first part, the syntheses of aryl-substituted phthalocyanines are described. The key intermediate, an aryl-substituted phthalonitrile, was prepared by a Pd(0)-catalysed Stille-coupling. The physical properties of tetra-(2,5-dirnetoxyphenyl)phthalocyanine (1a), tetraphenylphthalocyanine (1b) are discussed, An interesting display behaviour was characterised by spectroelectrochemistry in the case of 1b. Considering the system, unexpectedly high efficiencies of the resulting solar cells are observed for both dyes.

    The second part deals with two types of ruthenium tris-bipyridyl complexes. Syntheses of three carboxylated heteroleptic ruthenium complexes [Ru(bpy)2(bpy-R)](PF6)2 (bpy-R, R= (COOLi)n, n= 1, 2, 4) were synthesised for a study of the influence of the number of carboxylic groups on solar cell efficiencies. A lateral electron transfer mechanism for the dyes adsorbed on TiO2, is observed. Homoleptic and heteroleptic ruthenium complexes possessing the polymerisable groups vinyl, methoxyphenyl or thiophene were prepared for an investigation of the substituent effect on the dye-monolayer in the solar cell, both by electrochemistry and absorption spectroscopy. The methoxyphenyl-substituted complexes showed good polymerisation behaviour both at negative and at positive potentials. They also showed good resistance towards water when adsorbed onto TiO2 electrodes.

  • 12.
    Axén, Andreas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Bispidine derivatives as molecular tools for studies of (-Allyl)palladium complexes: Ligand synthesis and analythical cpplications1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Determination of structural and stereochemical features of reaction intermediates in transition metal catalysed reactions is of central interest. Bispidine derivatives as ligands in (π-allyl)palladium complexes in combination with 1H NMR spectroscopy are shown to be useful tools for revealing structural characteristics of these reaction intermediates. As a support for the conclusions drawn from NMR investigations, X-ray crystallography and calculated structures were used.

    Complexes of bispidine derivatives with varying substitution pattern and different pre-formed bis[(η3-allyl)palladium chloride] complexes were formed. The resulting complexes were analysed with 1H NMR spectroscopy, especially regarding the inter-ligand NOEs and the chemical shift effects due to anisotropic effects. It is shown that a large steric interaction between the aromatic systems of N,N'-diphenylated bispidine derivatives and various (π-allyl)palladium systems can be obtained. This steric interaction can be used for hindering rotation around C-C single bonds in (π-allyl)palladium ligands.

    Furthermore, the nearness of the aromatic systems and the (π-allyl)palladium ligand give rise to anisotropic effects that, after quantification, can give information about the structure in such complexes. The inter-ligand NOEs can, in the case of a N,N-diphenyl substituted bispidine derivative, be used for assignment of relative configuration in a set of acyclic (π-allyl)palladium ligands. With a bispidine derivative carrying chiral substituents, the inter-ligand NOEs were used for assignment of absolute configuration of (π-allyl)palladium ligands.

  • 13.
    Baudin, Micael
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Dynamics of metal oxides surfaces and the connection to reactivity2000Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Many interesting chemical and physical phenomena which take place on surfaces of metaloxides rely on the material's ability to repeatedly alter the electronic surface structure. Formost metal oxides this functionality is connected to the degree of non-stoichiometry andthe presence of structural defects. In many catalytic applications, for example, the metaloxide surfaces display optimal performance at rather high temperatures, and it is thereforeessential to include thermal distortions in any investigation of the mechanisms behind thefunctionality. It can be expected that dynamical changes in the surface structure will drastically alter the electronic structure, and thereby also the catalytic characteristics of thesurface.

    For metal oxide surfaces, experimental as well as theoretical data on surface dynamics(at non-zero temperatures) are virtually non-existent. The very few MD simulation studiesthat exist in the literature have exclusively dealt with the effect of temperature on stability,structure and ordering.

    This thesis describes molecular dynamics simulations and subsequent quantum-chemicalcalculations of metal oxide surfaces, and how the surface properties vary with temperature,crystal face and depth from the surface for three structurally different materials. The surfaces studied are the low-index faces of MgO, α-Al2O3(0001), undoped and dopedlow-index CeO2 surfaces, and the α-Al2O3(0001,010)/CeO2(011,011) interface. The emphasis lieson dynamic quantities, and the ionic motion is analysed in terms of mean-square displacements, ion migrations, instantaneous ionic displacements, as well as vibrational densities-of-states. Other properties discussed include surface energies, interplanar relaxations, and pairdistribution functions. The thesis also discusses the implication of short-time atomic-leveldynamical changes on reactivity.

  • 14.
    Berg, Helena
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    The rational design of lithium insertion materials for battery applications1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The transition-metal oxide spine1 LiMn2O4 is a promising cathode material for high-capacity lithium-ion batteries. Structure-property relationships pertaining to the electrochemical cycling behaviour of LiMn2O4 have been studied. The techniques exploited have been in situ X-ray and neutron diffraction, in combination with quantum-mechanical band-structure calculations. The results obtained lay the ground for an improved basis for designing new insertion materials.

    Substitution of Mn by Ni in LiMn2O4 and by Li in Li1+xMn2-xO4 give qualitatively different results: Ni is found to replace Mn directly, while Li takes up entirely new sites not observed earlier. Band-structure calculations have been used to better understand the crystallographically observed x-dependence of the Li1+xMn2-xO4 structure, and the underlying mechanisms of lithium-ion extraction/insertion.

    Quantitative observation of charge passed through the cell has also been related to the amount of lithium extracted to indicate possible sources of irreversible capacity loss, and how synthesis technique can influence cell performance.

    The LiMn2O4 structure has also been studied by neutron diffraction after treatment in strong-acid solutions, where Li ® H ion-exchange has been observed to take place. This process has strong implications for the dissolution of Mn2+ ions from the cathode into the electrolyte, especially at elevated temperatures, and the related corrosion process occurring at the cathode surface.

  • 15.
    Bergens, Arne
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Determination of Aromatic Amines and Nitro Compounds by Voltammetry and Amperometric Detection in Liquid Chromatography1991Licentiate thesis, monograph (Other academic)
  • 16.
    Berger, Rolf
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Materials Chemistry, Inorganic Chemistry. Oorganisk kemi.
    Bucur, Romulus V.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Materials Chemistry, Inorganic Chemistry. Oorganisk kemi.
    Diffusion in Copper Sulphides: An experimental study of chalcocite, chalcopyrite and bornite1996Report (Other scientific)
    Abstract [en]

    Diffusion measurements on three copper-containing sulphides have been performed by an electrochemical potentiometric method. -- The diffusion coefficient for chalcocite is in good agreement with values found previously, and a reasonable agreement is also found for chalcopyrite and bornite when our data are compared with values acquired at much higher temperatures with a different technique. The activation energies are remarkably similar for the three sulphides, considering that their relative errors are of a 10% magnitude, which indicates that the bonding strengths and the diffusion mechanisms are similar.

  • 17.
    Berglöf, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Supercritical Fluid Extraction (SFE) in Environmental Analysis1996Licentiate thesis, monograph (Other academic)
  • 18.
    Bergquist, J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    From MALDI-TOF MS to Two Dimensional CE-FTICR-MS of Proteins in Spinal Fluid2002In: Molecular Testing in Laboratory Medicine, 2002, p. 171-172Chapter in book (Other academic)
  • 19.
    Bergquist, J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    From molecule to man - using electrospray Fourier Transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) in proteomics2003In: ISMAS Silver Jubilee Symposium on Mass Spectrometry, 2003Chapter in book (Other academic)
  • 20.
    Bergson, G., Matsson, O.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Daniel Strömholm, The Svedberg och isotoperna2001In: Acta Academica Regiae Scientiarum Upsaliensis, ISSN ISBN 91-85832-14-6, Vol. 21, p. 53-60Article in journal (Other scientific)
  • 21.
    Bergstad, Katarina
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Molecular oxygen and hydrogen peroxide as mild oxidants in catalytic oxidations: Applications to palladium and osmium catalysis1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis the use of molecular oxygen and hydrogen peroxide as mild oxidants in transition metal-catalyzed oxidations of organic substrates is discussed. The thesis is divided into three parts.

    In the first part the use of heteropolyacids as robust oxygen-activating agents for aerobic reoxidation of zerovalent palladium is described. This aerobic reoxidation system has been applied to two different palladium-catalyzed reactions, the allylic oxidation of cyclohexene and the 1,4-oxidation of conjugated dienes. It was demonstrated that the presence of a benzoquinone, which can act both as an electron-transfer mediator and a coordinating ligand in the intermediate palladium π-allyl complex, is of importance for efficient reactions.

    In the second part, studies of systems for mild oxidations of tertiary amines to amine N-oxides are described. It was found that a fully reduced N1,N5- dialkylblocked flavin catalyzes the H2O2 oxidation of tertiary amines, giving the amine N-oxides in good yields in fast reactions. The reduced flavin acts as a precursor of the active catalyst, which is generated in the presence of air. Co(salophen), another investigated potential catalyst, was found to form a 1:2 complex with N-methylmorpholine N-oxide (NMO). This catalyst-product complex may inhibit the amine oxidations.

    The final part deals with in situ generation of NMO from N-methylmotpholine (NMM) in the osmium-catalyzed dihydroxylation of olefins. In a model study it was demonstrated that mCPBA in the presence of catalytic amounts of NMM is an efficient reoxidant for osmium(VI) in the dihydroxylation. Further investigations showed that H2O2 is an excellent oxidant in osmium-catalyzed dihydroxylations where NMM and a flavin are employed as cocatalysts. Different cis diols were synthesized in good yields by this procedure.

  • 22.
    Bergström, Sara
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Analytisk kemi.
    Development of Integrated Micro-Analytical Systems2003Licentiate thesis, monograph (Other scientific)
  • 23.
    Bergström, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Integrated Micro-Analytical Tools for Life Science2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Advances in life science require knowledge of active molecules in complex biological systems. These molecules are often only present for a certain time and at limited concentrations. Integrated micro-analytical tools for sampling, separation and mass spectrometric (MS) detection would meet these requests and are therefore continuously gaining interest. An on-line coupling of analytical functions provides shorter analysis time and less manual sample handling. In this thesis, improved compatibility of microdialysis sampling and multidimensional separations coupled to MS detection are developed and discussed.

    Microdialysis was used in vitro for determination of the non-protein bound fraction of the drug ropivacaine. The sampling unit was coupled on-line to capillary column liquid chromatography (LC) followed by ultraviolet or MS detection. For MS detection, the system was extended with a desalting step and an addition of internal standard. A method for MS screening of microdialysates, collected in vivo, was also developed. The method involved sampling and measurements of the chemical pattern of molecules that generally are ignored in clinical investigations. Chemometric tools were used to extract the relevant information and to compare samples from stimulated and control tissues.

    Complex samples often require separation in more than one dimension. On-line interfaces for sample transfer between LC and capillary electrophoresis (CE) were developed in soft poly(dimethylsiloxane) (PDMS). MS detection in the LC-CE system was optimised on frequent sampling of the CE peak or on high resolution in mass spectra using time-of-flight (TOF)MS or Fourier transform ion cyclotron resonance (FTICR)MS, respectively. Aspects on electrode positioning in the LC-CE interface led to development of an on-column CE electrode. A successful method for deactivation of the PDMS surface using a polyamine polymer was also developed. The systems were evaluated using peptides and proteins, molecules that are gaining increased attention in bioscience, and consequently also in chemical analysis.

    List of papers
    1. Determination of the free concentration of ropivacaine in plasma by packed capillary liquid chromatography: A comparison of ultrafiltration and microdialysis as sample preparation methods
    Open this publication in new window or tab >>Determination of the free concentration of ropivacaine in plasma by packed capillary liquid chromatography: A comparison of ultrafiltration and microdialysis as sample preparation methods
    2001 (English)In: Journal of Microcolumn Separations, ISSN 1040-7685, E-ISSN 1520-667X, Vol. 13, no 5, p. 197-201Article in journal (Refereed) Published
    Abstract [en]

    In this study, ultrafiltration and microdialysis have been compared as sample preparation methods to separate the free fraction of ropivacaine from the protein bound in 150 μL plasma. A liquid chromatographic system with packed capillary columns (0.2 mm internal diameter) was used to enhance sensitivity when analyzing the small sample volumes obtained after the ultrafiltration and the microdialysis. The microdialysis was performed with probes of our own construction, and to save analysis time, the microdialysis sampling was coupled on-line to the liquid chromatographic system. The reduction of back pressure in the microdialysis outlet tube and in the injector was found to be essential. The free fraction obtained with each method was equivalent: both gave a free fraction of 6%.

    Keywords
    microdialysis, ultrafiltration, free fraction, ropivacaine, capillary liquid chromatography
    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-93670 (URN)10.1002/mcs.1042 (DOI)
    Available from: 2005-10-28 Created: 2005-10-28 Last updated: 2017-12-14Bibliographically approved
    2. On-line coupling of microdialysis to packed capillary column liquid chromatography-tandem mass spectrometry demonstrated by measurement of free concentrations of ropivacaine and metabolite from spiked plasma samples
    Open this publication in new window or tab >>On-line coupling of microdialysis to packed capillary column liquid chromatography-tandem mass spectrometry demonstrated by measurement of free concentrations of ropivacaine and metabolite from spiked plasma samples
    2002 (English)In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 775, no 1, p. 79-87Article in journal (Refereed) Published
    Abstract [en]

    An on-line coupling of microdialysis to a packed capillary column switching liquid chromatographic system (0.2 mm I.D.) and mass spectrometric detection was developed. The microdialysates were collected in the loop of the first of three valves, coupled in direct series. A deuterated internal standard was added on-line by the middle valve and the third valve operated both a pre-column, for desalting of the physiological buffer used in the sampling procedure, and a separation column. The on-line system was used to study free concentrations of ropivacaine and its metabolite (PPX) in human plasma samples. The analytes were detected by electrospray ionization in a tandem mass spectrometer operating in multiple reaction monitoring mode. The free fractions of ropivacaine (200 nM total concentration) and PPX (20 nM total concentration) in spiked plasma samples were 12±3 and 47±5% (±standard deviation for day-to-day variations, n=3), respectively.

    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-93671 (URN)10.1016/S1570-0232(02)00280-5 (DOI)
    Available from: 2005-10-28 Created: 2005-10-28 Last updated: 2017-12-14Bibliographically approved
    3. Screening of microdialysates using on-line desalting and mass spectrometric detection
    Open this publication in new window or tab >>Screening of microdialysates using on-line desalting and mass spectrometric detection
    Show others...
    In: J. Chromatogr. AArticle in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-93672 (URN)
    Available from: 2005-10-28 Created: 2005-10-28Bibliographically approved
    4. On-column polymer-imbedded graphite inlet electrode for capillary electrophoresis coupled on-line with flow injection analysis in a poly(dimethylsiloxane) interface
    Open this publication in new window or tab >>On-column polymer-imbedded graphite inlet electrode for capillary electrophoresis coupled on-line with flow injection analysis in a poly(dimethylsiloxane) interface
    Show others...
    2003 (English)In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 24, no 11, p. 1723-1729Article in journal (Refereed) Published
    Abstract [en]

    A method for coupling an electrophoretic driven separation to a liquid flow, using conventional fused-silica capillaries and a soft polymeric interface is presented. A novel design of the electrode providing high voltage to the electrophoretic separation was also developed. The electrode consisted of a conductive polyimide/graphite imbedded coating immobilized onto the capillary electrophoresis (CE) column inlet. This integrated electrode gave the same separation performance as a commonly used platinum electrode. The on-column electrode also showed good electrochemical stability in chronoamperometric experiments. In addition, with this electrode design, the electrode position relative to the inlet end of the CE column will always be constant and well defined. The on-line flow injection analysis (FIA)-CE system was used with electrospray ionization (ESI)-time of flight (TOF)-mass spectrometry detection. The preparation of the PDMS (poly(dimethylsiloxane)) interface for FIA-CE is described in detail and used for initial tests of the on-column polymer-imbedded graphite inlet electrode. In this interface, a pressure-driven liquid flow, a make up CE electrolyte and a CE column inlet meet in a two-level cross (95 μm ID) in the PDMS structure, enabling independent flow characterization.

    Keywords
    Capillary electrophoresis, Flow injection, Hyphenation, On-column electrode, Poly(dimethylsiloxane)
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-94267 (URN)10.1002/elps.200305362 (DOI)
    Available from: 2006-04-07 Created: 2006-04-07 Last updated: 2017-12-14Bibliographically approved
    5. Development of a poly(dimethylsiloxane) interface for on-line capillary column liquid chromatography-capillary electrophoresis coupled to sheathless electrospray ionization time-of-flight mass spectrometry
    Open this publication in new window or tab >>Development of a poly(dimethylsiloxane) interface for on-line capillary column liquid chromatography-capillary electrophoresis coupled to sheathless electrospray ionization time-of-flight mass spectrometry
    2003 In: Anal. Chem., ISSN 0003-2700, Vol. 75, no 20, p. 5461-5467Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-93674 (URN)
    Available from: 2005-10-28 Created: 2005-10-28Bibliographically approved
    6. Polyamine deactivation of integrated poly(dimethylsiloxane) structures investigated by radionuclide imaging and capillary electrophoresis experiments
    Open this publication in new window or tab >>Polyamine deactivation of integrated poly(dimethylsiloxane) structures investigated by radionuclide imaging and capillary electrophoresis experiments
    Show others...
    2005 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 77, no 3, p. 938-942Article in journal (Refereed) Published
    Abstract [en]

    The poly(dimethylsiloxane) (PDMS) material provides a number of advantageous features, such as flexibility, elasticity, and transparency, making it useful in integrated analytical systems. Hard fused-silica capillary structures and soft PDMS channels can easily be combined by a tight fit, which offers many alternatives for structure combinations. PDMS and fused silica are in different ways prone to adsorption of low levels of organic compounds. The need for modification of the inner wall surface of PDMS channels may often be necessary, and in this paper, we describe an easy and effective method using the amine-containing polymer PolyE-323 to deactivate both fused-silica and PDMS surfaces. The adsorption of selected peptides to untreated surfaces was compared to PolyE-323-modified surfaces, using both radionuclide imaging and capillary electrophoresis experiments. The polyamine modification displayed a substantially reduced adsorption of three hydrophobic test peptides compared to the native PDMS surface. Filling and storage of aqueous solution were also possible in PolyE-323-modified PDMS channels. In addition, hybrid microstructures of fused silica and PDMS could simultaneously be deactivated in one simple coating procedure.

    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-93675 (URN)10.1021/ac0492618 (DOI)
    Available from: 2005-10-28 Created: 2005-10-28 Last updated: 2017-12-14Bibliographically approved
    7. A simplified multidimensional approach for analysis of complex biological samples: on-line LC-CE-MS
    Open this publication in new window or tab >>A simplified multidimensional approach for analysis of complex biological samples: on-line LC-CE-MS
    Show others...
    2006 (English)In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 131, no 7, p. 791-798Article in journal (Refereed) Published
    Abstract [en]

    Information on protein expression, disease biomarkers or surrogate markers and genetic disorders can nowadays be achieved from analysis of complex biological samples by liquid separation coupled to mass spectrometric (MS) detection. This paper describes fast multidimensional separation by on-line liquid chromatography (LC) and capillary electrophoresis (CE), followed by electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FTICR) MS detection. This detector provides ultrahigh resolution of the detected ions, mass accuracy at the ppm-level and high sensitivity. Most of the challenge of this system lies in the development of a new interface for the on-line coupling of LC to CE. The interface developed in poly(dimethylsiloxane) provides a RSD for injection repeatability of <3.5% and surface control for unspecific binding by deactivation with a cationic polymer, PolyE-323. We have evaluated the interface, as well as the overall system, with respect to robustness and deconvolution ability. Sequence coverage for bovine serum albumin (BSA) of 93% showed a high recovery of sample in the different transfer steps through the system. The detection limit for identification is 277 ng mL−1 (or 280 nM) on average for peptides. In the future, we expect LC-CE-MS to be a novel strategy for elucidating the chemistry of biological matrices.

    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-80932 (URN)10.1039/b601660j (DOI)
    Available from: 2006-06-29 Created: 2006-06-29 Last updated: 2017-12-14Bibliographically approved
    8. Poly(dimethylsiloxane)-Based Microchip for Two-Dimensional Solid-Phase Extraction-Capillary Electrophoresis with an Integrated Electrospray Emitter Tip
    Open this publication in new window or tab >>Poly(dimethylsiloxane)-Based Microchip for Two-Dimensional Solid-Phase Extraction-Capillary Electrophoresis with an Integrated Electrospray Emitter Tip
    Show others...
    2005 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 77, no 16, p. 5356-5363Article in journal (Refereed) Published
    Abstract [en]

    A microchip in poly(dimethylsiloxane) (PDMS) for in-line solid-phase extraction-capillary electrophoresis-electrospray ionization-time-of-flight mass spectrometry (SPE-CE-ESI-TOF-MS) has been developed and evaluated. The chip was fabricated in a novel one-step procedure where mixed PDMS was cast over steel wires in a mold. The removed wires defined 50-um cylindrical channels. Fused-silica capillaries were inserted into the structure in a tight fit connection. The inner walls of the inserted fused-silica capillaries and the PDMS microchip channels were modified with a positively charged polymer, PolyE-323. The chip was fabricated in a two-level cross design. The channel at the lower level was packed with 5-um hyper-cross-linked polystyrene beads acting as a SPE medium used for desalting. The upper level channel acted as a CE channel and ended in an integrated emitter tip coated with conducting graphite powder to facilitate the electrical contact for sheathless ESI. An overpressure continuously provided fresh CE electrolyte independently of the flows in the different levels. Further studies were carried out in order to investigate the electrophoretic and flow rate properties of the chip. Finally, six-peptide mixtures, in different concentrations, dissolved in physiological salt solution was injected, desalted, separated, and sprayed into the mass spectrometer for analysis with a limit of detection in femtomole levels.

    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-74074 (URN)10.1021/ac050495g (DOI)16097780 (PubMedID)
    Available from: 2005-08-26 Created: 2005-08-26 Last updated: 2017-12-14Bibliographically approved
  • 24.
    Bergström, Örjan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Lithium-ion insertion in a V6O13 cathode1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The transition metal oxide V6O13 is a promising cathode material for high-capacity lithium-polymer batteries in conjunction with a lithium-metal anode. The electro-chemical behaviour of V6O13 has its origin in the ability of the vanadium ions to change their-oxidation states, combined with the open nature of its crystal structure which allows lithium ions to diffuse through it. When incorporated into the cathode, the material passes through a series of lithiated phases as the battery is discharged. Inthis thesis, structure-property relationships of these lithiated phases have been studied. The techniques used have been in situ X-ray powder diffraction and single-crystal X-ray diffraction on electrochemically lithiated samples, in combination with electrochemical cycling.

    Five different lithiated phases were identified : LixV6O13 for x = 0.5, 1.0, 2.0, 3.0 and 6.0 at potentials 2.78, 2.68, 2.52, 2.45 and 2.00V vs. Li/Li+, respectively. The structures of the x = 0, 2.0 and 3.0 phases have been investigated using single-crystal techniques; deformation electron density refinement has been performed for the x=0 and 2.0 phases. The reduction (from V5+ to V4+) of one of the threeindependent vanadium atoms (V2) in the asymmetric unit can be identified with some degree of certainty as Li2V6O13 is formed. On this basis, a proposal is made for the complete sequence of vanadium oxidation-state changes for the entire lithium insertion process.

  • 25.
    Berlin, S.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Ericsson, C
    Engman, L
    Construction of Tetrahydrofuran-3-ones from Readily Available Organochalcogen Precursors via Radical Carbonylation/Reductive Cyclization2002Article in journal (Other scientific)
  • 26.
    Berlin, Stefan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Construction of Five-Membered Heterocycles via Radical Cyclization2001Licentiate thesis, monograph (Other scientific)
  • 27.
    Berlin, Stefan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Construction of Five-Membered Heterocyclic Compounds via Radical Cyclization2003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes how radical cyclization chemistry can be applied for the construction of heterocyclic compounds.

    In the first part, a series of electron deficient α-phenylselenenylalkenes were prepared via a PhSeCl-addition/HCl-elimination sequence. Allyl- and propargylamines readily underwent conjugate addition to these species to produce pyrrolidines or dihydropyrrol derivatives, after triethylborane initiated reductive radical cyclization in the presence of tris(trimethylsilyl)silane.

    The second part describes a convergent synthesis of the pineal hormone melatonin. The indole nucleus is secured via a tris(trimethylsilyl)silane mediated 5-exo radical cyclization. The protocol provides convenient and simple access to compounds useful for studies of biological activity and structure activity relationships.

    The third part describes construction of substituted tetrahydrofuran-3-ones and pyrrolidin-3-ones. Regioselective ring-opening of epoxides or aziridines with benzeneselenolate/tellurolate, followed by Michael addition to electron deficient alkynes afforded the corresponding O/N-vinylated compounds. The tetrahydrofuran-3-ones and pyrrolidin-3-ones were secured via radical carbonylation/reductive cyclization using pressurized carbon monoxide (80 atm).

    The fourth part is concerned with the effect of an N-protecting group on the cyclization of 2-substituted-3-aza-5-hexenyl radicals. Relative energies for reactants and transition states were determined using density functional calculations. Reactant and transition state conformers leading to cis-product were lower in energy than those leading to trans-product. The results can be explained by the unfavorable 1,2-strain present in chair-equatorial and boat-equatorial conformers.

    List of papers
    1. A Radical Cyclization Route to Pyrrolidines Based on Conjugate Addition to Electron Deficient Phenylselenenylalkenes
    Open this publication in new window or tab >>A Radical Cyclization Route to Pyrrolidines Based on Conjugate Addition to Electron Deficient Phenylselenenylalkenes
    2000 In: Tetrahedron Letters, Vol. 41, no 19, p. 3701-3704Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-90418 (URN)
    Available from: 2003-05-12 Created: 2003-05-12Bibliographically approved
    2. Efficient Route to the Pineal Hormone Melatonin by Radical-Based Indole Synthesis
    Open this publication in new window or tab >>Efficient Route to the Pineal Hormone Melatonin by Radical-Based Indole Synthesis
    2003 (English)In: Synthetic Communications, ISSN 0039-7911, E-ISSN 1532-2432, Vol. 33, no 20, p. 3631-3641Article in journal (Refereed) Published
    Abstract [en]

    The hormone melatonin, which is known to have a range of important biological effects, has been prepared in a high-yielding route that features formation of the indole nucleus by radical cyclization. Mediation of the radical cyclization by tristrimethylsilylsilane (TTMSS) is more efficient than by N-ethylpiperidine hypophosphite.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-90419 (URN)10.1081/SCC-120024751 (DOI)
    Available from: 2003-05-12 Created: 2003-05-12 Last updated: 2017-12-14Bibliographically approved
    3. Construction of Tetrahydrofuran-3-ones from Readily Available Organochalcogen Precursors via Radical Carbonylation/Reductive Cyclization
    Open this publication in new window or tab >>Construction of Tetrahydrofuran-3-ones from Readily Available Organochalcogen Precursors via Radical Carbonylation/Reductive Cyclization
    2002 In: Organic Letters, Vol. 4, p. 3-6Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-90420 (URN)
    Available from: 2003-05-12 Created: 2003-05-12Bibliographically approved
    4. Radical Carbonylation/Reductive Cyclization for the Construction of Tetrahydrofuran-3-ones and Pyrrolidin3-0nes
    Open this publication in new window or tab >>Radical Carbonylation/Reductive Cyclization for the Construction of Tetrahydrofuran-3-ones and Pyrrolidin3-0nes
    In: Journal of Organic ChemistryArticle in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-90421 (URN)
    Available from: 2003-05-12 Created: 2003-05-12Bibliographically approved
    5. On the origin of cis selectivity in the cyclization of N-protected 2-substituted 3-aza-5-hexenyl radicals: a density functional study
    Open this publication in new window or tab >>On the origin of cis selectivity in the cyclization of N-protected 2-substituted 3-aza-5-hexenyl radicals: a density functional study
    Show others...
    2004 (English)In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 69, no 5, p. 1487-1491Article in journal (Refereed) Published
    Abstract [en]

    Cyclization of the N-dimethylphosphinoyl-2-methyl-3-aza-5-hexenyl radical has been studied at the UB3LYP/6-31+G(d)//UB3LYP/6-31G(d) hybrid density functional level. The corresponding radical precursor has been synthesized and found to give cis/trans ratios of up to 10/1 in reductive radical cyclizations. The relative energies of reactant and transition state conformers were determined. In discord with the Beckwith-Houk model, it has been found that chair-axial transition states, which lead to cis products, are lowest in energy, rationalizing the observed experimental diastereoselectivity.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-90422 (URN)10.1021/jo030294h (DOI)14987001 (PubMedID)
    Available from: 2003-05-12 Created: 2003-05-12 Last updated: 2017-12-14Bibliographically approved
  • 28.
    Bertilsson, Sophie
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Asymmetric Formation and Isomerization of Three-Membered Rings: Catalyst Development and Evaluation2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Enantiopure α-amino acid derivatives were prepared using a protocol which allows for highly controlled regio- and chemoselectivity in the hydrogenation/ hydrogenolysis of aza-Diels-Alder adducts. One of the resulting α-amino esters, (1S,3R,4R)-2-azabicyclo[2.2.1]heptane-3-carboxylic acid ethyl ester, was utilized further as a catalyst precursor.

    Significant improvements were achieved in the asymmetric lithium amide-mediated epoxide rearrangement reaction. An efficient catalytic system was developed, based on 5 mol% of (1S,3R,4R)-3-(amino)methyl-2-azabicyclo[2.2.1]heptanes and stoichiometric amounts of lithium diisopropylamide (LDA). With pyrrolidine or (2R,5R)-dimethylpyrrolidine as the amine moiety, the isomerization into allylic alcohols was accomplished for 5–7-membered cycloalkene oxides and (Z)-octene oxide with yields of >90% and enantioselectivities up to 99% ee. The studies indicate that the active catalyst species is a monomer, which is in equilibrium with inactive aggregates. The addition of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) led to a reaction rate acceleration. In the catalytic reaction, where there is a competing LDA-mediated rearrangement, the presence of DBU also improved the enantioselectivity.

    Furthermore, the asymmetric addition of carbenes and nitrenes to olefins was investigated. N,N'- and N,O-oxazolines were evaluated as ligands in the Cu-catalyzed aziridination of alkenes. Two of the oxazolines formed highly active catalysts (90% yield). However, the enantioselectivity was moderate (≤34% ee). Another catalyst, tetrakis-[(1S,3R,4R)-2-(p-tert-butylbenzene)sulphonyl-2-azabicyclo[2.2.1]heptane-3-carboxylate]dirhodium(II) was prepared and successfully applied in the reaction of styrenes and cyclic enol ethers with phenyl- and vinyldiazoacetates, affording cyclopropanes in up to 95% yield and 92% ee. In contrast to earlier observations, the best results were obtained with electron-rich olefins.

  • 29.
    Besev M, Engman L,
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Diastereocontrol by Hydroxyl Auxiliary in the Synthesis of Pyrrolidines via Radical Cyclization2002In: Org. Lett., no 4, p. 3023-Article in journal (Other scientific)
  • 30.
    Besev, Magnus
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Pyrrolidines via Radical Cyclization2000Licentiate thesis, monograph (Other scientific)
  • 31.
    Beşev, Magnus
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry, Organic Chemistry.
    Radical Cyclization Approaches to Pyrrolidines2002Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Five-membered rings are readily prepared by 5-exo-trig radical cyclization. This thesis is concerned with novel methodology for pyrrolidine synthesis. We have synthesised selenium containing radical precursors from aziridines and α-phenylseleno ketones, and cyclized them to 2,4- and 3,4-disubstituted pyrrolidines. A few examples of 5-exo-dig cyclization were also demonstrated. In another study we investigated the capacity of the nitrogen protecting group to direct diastereoselectivity in the formation of 2,4-disubstituted pyrrolidines. The diphenylphosphinoyl protecting group directed cyclization to occur in a highly cis-selective manner. When cyclizations were performed at 17 oC, cis/trans-ratios as high as 24/1 were obtained. In contrast, cyclization of the unprotected pyrrolidine precursor afforded the trans-diastereomer as the major product (cis/trans = 1/3.3 – 1/20). We also examined the use of a hydroxyl auxiliary for controlling diastereoselectivity in radical cyclization. The required selenium containing radical precursors were synthesised from 2-cyanoaziridines by addition of organometallic reagents, reduction of the resulting aziridine ketone, and benzeneselenol ring-opening of the aziridine. Cyclization at 17 oC produced 2,4-disubstituted pyrrolidines substantially enriched in the trans-isomer (cis/trans = 1/9 – 1/12). Novel radical cyclization approaches to thiazolines and pyrrolines were also tried.

    The thesis also describes attempts to improve the Hassner aziridine synthesis by employing stannous chloride as a functional group tolerant reducing agent.

  • 32.
    Björefors, Fredrik
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Fundamental investigations and applications of microelectrode based detections in flowing solutions1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The influence of diffusional, migrational and convective mass transport at microelectrodes employed for voltammetric and amperometric detection in flowing solutions has been investigated. Special attention was paid to the influence of convection on the IR drop in organic solvents and on the transport of reaction products between individual electrode bands of microarray electrodes. A flow injection system was also designed to study the stability of mercury films coated on microelectrodes for the purpose of stripping analysis.

    Increased influence of convection, obtained by altering the flow rate or by changing the position of the microelectrode in a wall-tube flow cell, at low support ratios in organic solvents was found to result in decreased currents as a consequence of the inability to maintain a sufficient amount of ions at the vicinity of the microelectrode surface. Successful determinations of the water content in butter and margarine could be performed in an acetone based flow injection system, provided that the detection potential was chosen to accommodate the different support ratios in the injected solutions.

    The degree of redox cycling at interdigitated microarray electrodes was found to increase if the flow rate was reduced from 20 to 2 µl/min. Even at these low flow rates, the degree of redox cycling in stationary solutions was, however, always larger compared to the values obtained under the influence of convection. A microarray electrode was also employed to improve the selectivity in the detection of poorly separated species in capillary electrophoresis.

    By employing a flow injection system, it was found that the stability of mercury films plated on platinum and carbon fibre microelectrodes could be improved as potential control could be maintained during solution exchange and between individual experiments. Stripping voltammetric determinations of nickel at nM concentrations and of copper in a low ionic strength solution was demonstrated in the flow injection system.

  • 33. Björkman, M.
    et al.
    Långström, B
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Functionalization of 11C-labeled olefins via a Heck couplin reaction.2000In: Journal of the Chemical Society-Perkin Transactions, ISSN 1470-4358, Vol. 1, no 18, p. 3031-34Article in journal (Other scientific)
  • 34.
    Björkman, Margareta
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Palladium-promoted synthesis of compounds labelled with ¹¹C: Synthesis of ¹¹C-labelled prostacyclin and prostaglandin analogues2000Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Palladium-promoted reactions have been employed for the synthesis of compounds labelled with 11C (t½ = 20.3 min). The precursor [11C]methyl iodide was used in palladium-promoted cross-coupling reactions with organostannanes. With this method, large molecules with several functional groups, that is prostacyclin analogues, have been synthesised in up to 54 % decay-corrected radiochemical yield, calculated from [11C]methyl iodide. However, since this method did not afford reproducible yields, a second method where copper(I) was used as a co-catalyst with palladium, was developed. In the second method, a lower reaction temperature could be used and more reproducible yields were obtained. Employing this method, a prostaglandin analogue was synthesised in 34 % decay-corrected radiochemical yield calculated from [11C]methyl iodide. The total synthesis time was 30 min and the radiochemical purity was higher than 95 %. The specific radioactivity of the compounds obtained with these two methods was approximately 100 GBq/μmol.

    11C-Labelled aliphatic and aromatic alkenes were synthesised from [11C]methyl iodide in a Wittig olefination reaction using a published method. The 11C-labelled alkenes were reacted with five aromatic halidein Heck coupling reactions, producing five [11C]stilbene analogues in 34-40 % decay-corrected radiochemical yield. The radiochemical purity was higher than 95 % and the total synthesis timwas 40 min.

    11C-Labelled alkenes were also synthesised from 11C-labelled aldehydes. The 11C-labelled aldehydes were obtained from [11C]carbon monoxide in a palladium-mediated formylation of aryl iodides in 51-87 % radiochemical yield, determined by analytical LC and corrected for trappinefficiency. A range of palladium catalysts and hydride reagents were investigated. The labelled aldehydes were used in a subsequent Wittig olefination reaction where various Wittig salts were employed tsynthesise a variety of alkenes. The radiochemical yields were 30-76 %, determined by analytical LC.

  • 35.
    Blomquist, G.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Engler, H.
    Wall, A.
    Sandell, J.
    Koivisto, P.
    Långström, B.
    Reference tissue methods in analyzing brain uptake of PIB with PET2003In: EANM, Amsterdam, 2003Conference paper (Other scientific)
  • 36.
    Bohl E, Carlsson J, Edwards K, Sjöberg S, Gedda L
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    SLT-particles for twostep targeting in boron neutron capture therapy2001In: Frontiers in neutron capture therapy, p. 1069-1075Article in journal (Other scientific)
  • 37.
    Bohl Kullberg E, Carlsson J, Edwards K, Capala J, Sjöberg S, Gedda L.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Introductory Experiments On Ligand Liposomes as Delivery Agents for Boron Neutron Capture Therapy2003In: International Journal of Oncology, no 23, p. 461-467Article in journal (Other scientific)
  • 38.
    Borbath, I
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Gregoire, V
    Bergström, M
    Laryea, D
    Långström, B
    P.S,
    Use of 5-[(76)Br]bromo-2'-fluoro-2'.deoxyuridine as a ligand for tumour proliferation: validation in an animal tumour model2002In: Eur. J. Nucl. Med. Mol. Imaging, Vol. 1, no 29, p. 19-27Article in journal (Other scientific)
  • 39. Brandt, P
    et al.
    Andersson, P G
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Exploring the chemistry of 3-substituted 2-azanorbornyls in asymmetric catalysis.2000In: Synlett, ISSN 0936-5214, no 8, p. 1092-1106Article in journal (Other scientific)
  • 40.
    Brandt P, Hedberg C, Andersson P.G
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    New Mechanistic Insights into the Ir-(phosphano-oxazoline) Catalysed Hydrogenation of Unfunctinalized Olefines: A DFT and Kinetic Study2003In: Chem. Eur. J., no 9, p. 339-Article in journal (Other scientific)
  • 41.
    Bratt K, Sunnerheim K, Bryngelsson S, Fagerlund A, Engman L, Andersson R.E, Dimberg L.H
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Avenanthramides in Oats (Avena sativa L.) and Structure-Antioxidant Activity Relationships2003In: J. Agric. Food Chem, no 51, p. 594-Article in journal (Other scientific)
  • 42.
    Bratt, K
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Sunnerheim, K
    Bryngelsson, S
    Fagerlund, A
    Engman, L
    Häll, Dimberg L.
    Avenanthramides in Oats: Structure - Antioxidant Activity Relationsip2003In: J. Agric Food Chem., no 51, p. 594-600Article in journal (Other scientific)
  • 43.
    Bratt K, Sunnerheim K., Nordenhem H., Nordlander G., Långström B.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Pine Weevil (Hylobius abietis) Antifeedants from Lodgepole Pine (Pinus contorta)2001Article in journal (Other scientific)
  • 44.
    Bratt, Katharina
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Secondary plant metabolites as defence against herbivores and oxidative stress: Synthesis, isolation and biological evaluation2000Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis the isolation, synthesis and biological evaluation of natural defense compounds against herbivores or oxidative stress is discussed.

    The first part concerns the metabolites of platyphylloside ((5S)-5-hydroxy-1,7-bis-(4-hydroxyphenyl)-3-heptanone-5-O-β-D-glucopyranoside), a phenolic glucoside found in birch (Betula pendula) that possess digestibility inhibiting activity in herbivores. The structure-activity relationship of platyphylloside analogues were investigated regarding to stereochemistry and substitution pattern on the aromatic rings. The metabolites formed in vitro in rumen fluid were synthesized and the active metabolite determined as (R)-centrolobol (1,7-bis-(4-hydroxyphenyl)-3-heptanol). Treatment of mice and rats with rac-centrolobol did not effect either food intake or body weight. Effect of platyphylloside in moose was also investigated, and the results indicate that there was an in vivo digestibility reducing activity.

    The second part concerns naturally occurring antioxidants. Avenanthramides is a class of phenolic antioxidants found in oat (Avena sativa). Avenanthramides derived from either anthranilic acid or 5-hydroxyanthranilic acid were evaluated for their antioxidative capacity and quantified in oat extracts. Avenanthramides derived from 5-hydroxyanthranilic acid possessed higher activity than those from anthranilic acid. The order of reactivity depending on substitution pattern on the phenolic moiety was found to be 4-hydroxy < 4-hydroxy-3-methoxy < 3,5-dimethoxy-4-hydroxy and 3,4-dihydroxy. A synthesis towards antioxidative compounds such as 4-deoxycarbazomycin was developed.

    The third part concerns the isolation of compounds from Lodgepole pine (Pinus contorta) with antifeedant activity against pine weevil (Hylobius abietis). Two compounds possessing high activity were isolated and identified.

  • 45. Bregadze, V I.
    et al.
    Sivaev, I.
    Bruskin, A.
    Sjöberg, S.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Nesterov, V.
    Antipin, M.
    Synthesis of Schiff bases and monoalkylamino derivatives of closododecaborae(2-) anion2000In: Contemporary Boron ChemistryArticle in journal (Other scientific)
  • 46.
    Bregadze V, Sivaev I, Sjöberg S
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Synthesis of Functional Derivatives of Cobalt Bis(1,2-dicarolide) Anion for BNCT.2002In: Research and Development in Neutron Capture Therapy, p. 13-17Article in journal (Other scientific)
  • 47.
    Bylund, Dan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Chemometric Tools for Enhanced Performance in Liquid Chromatography-Mass Spectrometry2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    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.

  • 48.
    Bäckström, Daniel
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Allard, Erik
    Danielsson, Rolf
    Sjöberg, Per
    Bergquist, Jonas
    Comparing CE-MS fingerprints of urine samples, obtained after intake of coffee, tea or waterManuscript (Other academic)
  • 49.
    Bökman, C. Fredrik
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry, Analytical Chemistry.
    Analytical Aspects of Atmospheric Pressure Ionisation in Mass Spectrometry2002Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The actual signal recorded with an analytical instrument is not always a true reflection of the analysed sample. In this thesis a further insight of the atmospheric pressure ionisation processes electrospray (ESI) and atmospheric pressure chemical ionisation (APCI) has been endeavoured, to provide a deeper understanding of and ways to minimize this bias.

    A response model for ESI has been modified and used to study the influence of solvent composition on the observed mass spectrometric signal. The response model divides the response into an analyte partitioning coefficient and an instrumental response factor. A number of experimental parameters influencing the response were investigated including spray position relative to the orifice, spray potential, nebulizer and curtain gas flow rates, ionic strength and organic content of the sprayed solution. The history of the generated droplets turned out to be of significant importance to both the partitioning coefficients and the instrumental response factor. Furthermore, it was found that the total ionic strength and not only the electrolyte concentration will influence the instrumental response factor.

    In addition, based on the importance of hydrophobicity and electrophoretic mobility, a model was proposed for the ion distribution within the electrosprayed droplets.

    The coupling of an electrochemical (EC) cell to a mass spectrometric (MS) system has been evaluated. The coupling of the EC cell to the MS was made to decouple the cell from the high voltage circuit of the ESI. The feasibility for analyte ionisation, sample pre-concentration and solvent exchange as well as studying redox reaction products was shown.

  • 50.
    Carlsson, Annika
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Spectroscopy and Pattern Recognition as Alternative Methods to Biological Assays1995Licentiate thesis, monograph (Other academic)
123456 1 - 50 of 277
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