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  • 201. Bäckvall, Jan-E.
    et al.
    Andersson, Pher
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Stereocontrolled Oxaspirocyclization of Conjugated Dienes via Palladium Catalysis1991In: J. Org. Chem. Soc, Vol. 56, no 7, p. 2274-2276Article in journal (Refereed)
  • 202. Bäckvall, Jan-E.
    et al.
    Andersson, Pher
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Vågberg, Jan O.
    Stereocontrolled Lactonization Reactions via Palladium-Catalysis1989In: Tetrahedron Letters, Vol. 30, no 1, p. 137-140Article in journal (Refereed)
  • 203. Bäckvall, Jan-E.
    et al.
    Nilsson, Ylva
    Andersson, Pher
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Gatti, Roberto
    Wu, Jinchang
    Carbon-Carbon Bond Formation in Palladium(II)-Catalyzed Intramolecular 1,4-Oxidation of Conjugated Dienes1994In: Tetrahedron Letters, Vol. 35, no 31, p. 5713-5716Article in journal (Refereed)
  • 204.
    Bäckvall, Jan-Erling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Organic Chemistry.
    Andersson, Pher
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Organic Chemistry.
    Stone, Guy
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Organic Chemistry.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Organic Chemistry.
    Syntheses of (±)-α- and (±)- γ- Lycorane via a Stereocontrolled Organopalladium Route1991In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 56, no 9, p. 2988-2993Article in journal (Refereed)
    Abstract [en]

    Total syntheses of (+/-)-alpha-and (+/-)-gamma-lycorane are described. The key steps in the syntheses are the stereocontrolled palladium-catalyzed intramolecular 1,4-chloroamidation of 12 to 13 and the subsequent anti-stereoselective copper-catalyzed S(N)2' reaction of allylic chloride 13 with [3,4-(methylenedioxy)phenyl]magnesium bromide to give 14. Hexahydroindole 14 has the required relative stereochemistry between carbons 3a, 7, and 7a for alpha-lycorane (1a) and was transformed to the latter via 15 and 16. The epimeric gamma-lycorane (2) was obtained by performing the Bischler-Napieralski cyclization on 14, which led to a highly stereoselective isomerization to give exclusively 17. Compound 17 was subsequently transformed to 2. The overall yield from ester 8 to (+/-)-alpha- and (+/-)-gamma-lycorane was 40 and 36%, respectively.

  • 205.
    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.

  • 206.
    Bökman, C Fredrik
    et al.
    Clinical Chemistry Laboratory, Falun Central Hospital.
    Bylund, Dan
    Department of Natural Sciences, Mid Sweden University.
    Markides, Karin E
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Sjöberg, Per J. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Relating chromatographic retention and electrophoretic mobility to the ion distribution within electrosprayed droplets.2006In: Journal of the American Society for Mass Spectrometry, ISSN 1044-0305, E-ISSN 1879-1123, Vol. 17, no 3, p. 318-24Article in journal (Refereed)
    Abstract [en]

    Ions that are observed in a mass spectrum obtained with electrospray mass spectrometry can be assumed to originate preferentially from ions that have a high distribution to the surface of the charged droplets. In this study, a relation between chromatographic retention and electrophoretic mobility to the ion distribution (derived from measured signal intensities in mass spectra and electrospray current) within electrosprayed droplets for a series of tetraalkylammonium ions, ranging from tetramethyl to tetrapentyl, is presented. Chromatographic retention in a reversed-phase system was taken as a measure of the analyte's surface activity, which was found to have a large influence on the ion distribution within electrosprayed droplets. In addition, different transport mechanisms such as electrophoretic migration and diffusion can influence the surface partitioning coefficient. The viscosity of the solvent system is affected by the methanol content and will influence both diffusion and ion mobility. However, as diffusion and ion mobility are proportional to each other, we have, in this study, chosen to focus on the ion mobility parameter. It was found that the influence of ion mobility relative to surface activity on the droplet surface partitioning of analyte ions decreases with increasing methanol content. This effect is most probably coupled to the decrease in droplet size caused by the decreased surface tension at increasing methanol content. The same observation was made upon increasing the ionic strength of the solvent system, which is also known to give rise to a decreased initial droplet size. The observed effect of ionic strength on the droplet surface partitioning of analyte ions could also be explained by the fact that at higher ionic strength, a larger number of ions are initially closer to the droplet surface and, thus, the contribution of ionic transport from the bulk liquid to the liquid/air surface interface (jet and droplet surface), attributable to migration or diffusion will decrease.

  • 207.
    Bökman, C.Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry. Analytisk kemi.
    Zettersten, Camilla
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry. Analytisk kemi.
    Sjöberg, Per J.R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry. Analytisk kemi.
    Nyholm, Leif
    A Setup for the Coupling of a Thin-Layer Electrochemical Flow Cell to Electrospray Mass Spectrometry2004In: Analytical Chemistry, Vol. 76, no 7, p. 2017-2024Article in journal (Refereed)
    Abstract [en]

    A novel setup for the coupling of commercially available thin-layer cell to electrospray mass spectrometry (ESI-MS) which allows the elctrochemical reactions at the counter electrode to be straightforwardly separated from the flow into the mass spectrometer has been developed. In this way interferences from reaction products formed at the counter electrode can be minimized. This reduces the risk of changes in the mass spectra as a result of electrochemical reactions in the solution. The described setup also enables the working electrode to be positioned close to the electrospray (ESI) emitter without the need for a grounding point or a long transfer line between the electrochemical cell and the electrospray emitter. By decoupling the electrochemical reactions in the flow cell and those in the electrospray emitter, improved facilities for studies of electrochemical reactions are obtained through a better control of the potential of the working electrode. The setup has been used to study the oxidation of a drug (Olsalazine), which previously has been found to involve chemical follow-up reactions. It is also demonstrated that uncharged thiols can be detected in ESI-MS after spontaneous adsorption on a gold working electrode, followed by oxidative desorption to yield sulfinates or sulfonates. This adsorption and potential-controlled desorption has been used for the preconcentration of micromolar concentrations of 1-hexanethiol as well as for desalting of solutions containing micromolar concentrations of thiols. The results indicate that the present on-line coupling of an electrochemical cell to ESI-MS provides promising possibilities for sample preconcentration, matrix exchange (including desalting), and ionization of neutral compounds, such as thiols.

  • 208.
    Büttner, Frank
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I. Organisk kemi.
    Erdélyi, Máté
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I. Organisk kemi.
    Arvidsson, Per
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I. Organisk kemi.
    cyclo(ß-Asp-ß3-hVal-ß3-hLys)-Solid-Phase Synthesis and Solution Structure of a Water Soluble ß-Tripeptide2004In: Helvetica Chimica Acta, Vol. 87, p. 2735-2741Article in journal (Refereed)
  • 209. Büttner, Frank
    et al.
    Norgren, Anna S.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry, Organic Chemistry.
    Zhang, Suode
    Prabpai, Samran
    Kongsaeree, Palangpon
    Arvidsson, Per I.
    Cyclic β-tetra- and pentapeptides: Synthesis through on-resin cyclization and conformational studies by X-ray, NMR and CD spectroscopy and theoretical calculations2005In: Chemistry--A European Journal, ISSN 0947-6539, Vol. 11, no 21, p. 6145-6158Article in journal (Refereed)
  • 210.
    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)
  • 211.
    Carlsson J, Bohl Kullberg E, Capala J, Sjöberg S, Edwards K, Gedda L.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Ligands liposomes and boron neutron capture therapy2003In: Journal of Neuro-Oncology, no 62, p. 47-59Article in journal (Other scientific)
  • 212.
    Carlsson, Jörgen
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology.
    Bohl Kullberg, Erika
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology. Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Capala, Jacek
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology.
    Sjöberg, Stefan
    Edwards, Katarina
    Department of Physical Chemistry.
    Gedda, Lars
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology.
    Ligand liposomes and boron neutron capture therapy2003In: Journal of Neuro-Oncology, Vol. 62, p. 47-Article in journal (Refereed)
  • 213.
    Casher, D.L
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Tsuji, H
    Katkevics, Sano A
    Katkevics, M
    Toshimitsu, A
    Tamao, K
    Kubota, M
    Kobayashi, T
    Ottosson, C.H
    David, D
    Michl, J.
    The Disilane Chromophore: Photoelectron an dElectronic Spectra of Hexaalkyldisilanes and 1, (n+,)-Disila[n.n.n]propellanes2003In: J Phys Chem A, no 107, p. 3559-3566Article in journal (Other scientific)
  • 214.
    Chajara, Khalil
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry II. Organisk kemi.
    Ottosson, Henrik
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry II. Organisk kemi.
    An improved pathway to 6,6-disubstituted fulvenes2004In: Tetrahedron Letters, no 45, p. 6741-6744Article in journal (Refereed)
    Abstract [en]

    Pentafulvenes with alkyl and/or aryl substituents at the exocyclic position are formed rapidly in high yields through reaction of crystalline sodium cyclopentadienide directly with the appropriate ketones.

  • 215.
    Cheng, Aiping
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Syntheses of 11C and 76Br labeled compounds via organostannanes using the Stille cross-coupling reaction and oxidative bromination2001Licentiate thesis, monograph (Other scientific)
  • 216.
    Cosquer, Guirec Y., Wang J., Naeslund C., Adams D.M., Ji W., Zhuo J-C., Anisuzzaman A.K.M.,Sjöberg S., Barth R.F., Eriksson S., Tjarks W.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Synthesis and biological evaluation of carboranyl thymidines for BNTC2001In: 221st MEDI-151, p. 151-Article in journal (Other scientific)
    Abstract [en]

    221 st MEDI-151

  • 217.
    Dahlin, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    Microscale Tools for Sample Preparation, Separation and Detection of Neuropeptides2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The analysis of low abundant biological molecules is often challenging due to their chemical properties, low concentration and limited sample volumes. Neuropeptides are one group of molecules that fits these criteria. Neuropeptides also play an important role in biological functions, which makes them extra interesting to analyze. A classic chemical analysis involves sampling, sample preparation, separation and detection. In this thesis, an enhanced solid supported microdialysis method was developed and used as a combined sampling- and preparation technique. In general, significantly increased extraction efficiency was obtained for all studied peptides. To be able to control the small sample volumes and to minimize the loss of neuropeptides because of unwanted adsorption onto surfaces, the subsequent analysis steps were miniaturized to a micro total analysis system (µ-TAS), which allowed sample pre-treatment, injection, separation, manipulation and detection.

    In order to incorporate these analysis functions to a microchip, a novel microfabrication protocol was developed. This method facilitated three-dimensional structures to be fabricated without the need of clean room facilities.

    The sample pre-treatment step was carried out by solid phase extraction from beads packed in the microchip. Femtomole levels of neuropeptides were detected from samples possessing the same properties as microdialysates. The developed injection system made it possible to conduct injections from a liquid chromatographic separation into a capillary electrophoresis channel, which facilitated for advanced multidimensional separations. An electrochemical sample manipulation system was also developed. In the last part, different electrospray emitter tip designs made directly from the edge of the microchip substrate were developed and evaluated. The emitters were proven to be comparable with conventional, capillary based emitters in stability, durability and dynamic flow range. Although additional developments remain, the analysis steps described in this thesis open a door to an integrated, on-line µ-TAS for neuropeptides analysis in complex biological samples.

    List of papers
    1. 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
    2. 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
    3. 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
    4. On-line coupling of a microelectrode array equipped poly(dimethylsiloxane) microchip with an integrated graphite electrospray tip to electrospray mass spectrometry
    Open this publication in new window or tab >>On-line coupling of a microelectrode array equipped poly(dimethylsiloxane) microchip with an integrated graphite electrospray tip to electrospray mass spectrometry
    Show others...
    In: Article in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-93184 (URN)
    Available from: 2005-05-10 Created: 2005-05-10 Last updated: 2011-03-21
    5. Sheathless electrospray from polymer microchips
    Open this publication in new window or tab >>Sheathless electrospray from polymer microchips
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    2003 In: Analytical Chemistry, Vol. 75, no 15, p. 3934-3940Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-93185 (URN)
    Available from: 2005-05-10 Created: 2005-05-10 Last updated: 2011-03-21
    6. Capillary electrophoresis coupled to mass spectrometry from a polymer modified poly(dimethylsiloxane) microchip with an integrated graphite electrospray tip
    Open this publication in new window or tab >>Capillary electrophoresis coupled to mass spectrometry from a polymer modified poly(dimethylsiloxane) microchip with an integrated graphite electrospray tip
    Show others...
    2005 (English)In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 130, no 2, p. 193-199Article in journal (Refereed) Published
    Abstract [en]

    Hybrid capillary-poly(dimethysiloxane) (PDMS) microchips with integrated electrospray ionization (ESI) tips were directly fabricated by casting PDMS in a mould. The shapes of the emitter tips were drilled into the mould, which produced highly reproducible three-dimensional tips. Due to the fabrication method of the microfluidic devices, no sealing was necessary and it was possible to produce a perfect channel modified by PolyE-323, an aliphatic polyamine coating agent. A variety of different coating procedures were also evaluated for the outside of the emitter tip. Dusting graphite on a thin unpolymerised PDMS layer followed by polymerisation was proven to be the most suitable procedure. The emitter tips showed excellent electrochemical properties and durabilities. The coating of the emitter was eventually passivated, but not lost, and could be regenerated by electrochemical means. The excellent electrochemical stability was further confirmed in long term electrospray experiments, in which the emitter sprayed continuously for more than 180 h. The PolyE-323 was found suitable for systems that integrate rigid fused silica and soft PDMS technology, since it simply could be applied successfully to both materials. The spray stability was confirmed from the recording of a total ion chromatogram in which the electrospray current exhibited a relative standard deviation of 3.9% for a 30 min run. CE-ESI-MS separations of peptides were carried out within 2 min using the hybrid PDMS chip resulting in similar efficiencies as for fused silica capillaries of the same length and thus with no measurable band broadening effects, originating from the PDMS emitter.

    National Category
    Analytical Chemistry Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-93084 (URN)10.1039/b414592e (DOI)15665973 (PubMedID)
    Available from: 2005-05-03 Created: 2005-05-03 Last updated: 2017-12-14Bibliographically approved
    7. Sample pretreatment on a microchip with an integrated electrospray emitter
    Open this publication in new window or tab >>Sample pretreatment on a microchip with an integrated electrospray emitter
    Show others...
    2006 (English)In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 27, no 11, p. 2075-2082Article in journal (Refereed) Published
    Keywords
    Electrospray emitter, Microchip, PDMS, Sample pretreatment
    National Category
    Chemical Sciences Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-95129 (URN)10.1002/elps.200500763 (DOI)
    Available from: 2006-11-17 Created: 2006-11-17 Last updated: 2017-12-14Bibliographically approved
  • 218.
    Dahlin, Andreas P.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Bergström, Sara K.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Andrén, Per E.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, MMS, Medical Mass Spectrometry.
    Markides, Karin E.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Poly(dimethylsiloxane)-Based Microchip for Two-Dimensional Solid-Phase Extraction-Capillary Electrophoresis with an Integrated Electrospray Emitter Tip2005In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 77, no 16, p. 5356-5363Article in journal (Refereed)
    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.

  • 219.
    Danielsson, R.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Bylund, D.
    Markides, K.E.
    Matched filtering with background suppression for improved quality of base peak chromatograms and mass spectra in liquid chromatography - mass spectrometry2002In: Analytica Chimica Acta, no 454, p. 167-184Article in journal (Refereed)
  • 220.
    Danielsson, Rolf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Bäckström, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Ullsten, Sara
    Rapid multivariate analysis of LC/GC/CE data (single or multiple channel detection) without prior peak alignment2006In: Chemometrics and Intelligent Laboratory Systems, ISSN 0169-7439, E-ISSN 1873-3239, Vol. 84, no 1-2, p. 33-39Article in journal (Refereed)
    Abstract [en]

    One- or two-dimensional data obtained with LC/GC/CE and single or multiple channel detection (MS, UV/VIS) are often used as 'fingerprints' in order to characterize complex samples. The relation between samples is then explored by multivariate data analysis (PCA, hierarchical clustering), but inevitable more or less random variation in separation conditions obstructs the analysis. Several methods for peak alignment have been developed, with more or less increase of time and efforts for computations. In this work another approach is presented, based on a correlation measure less sensitive for variations in retention/migration time. The merits of the method as a fast initial data exploration tool are demonstrated for a case study of urine profiling with CE/MS.

  • 221.
    Diesen, Jarle Sidney
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Organic Chemistry.
    Asymmetric Hydrogenations of Imines, Vinyl Fluorides, Enol Phosphinates and Other Alkenes Using N,P-Ligated Iridium Complexes2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The research described in this thesis is directed toward the efficient, enantioselective synthesis of chiral products that have useful functionality. This goal was pursued through catalytic asymmetric hydrogenation, a reaction class that selectively introduces one or two stereocenters into a molecule in an atom-efficient step. This reaction uses a small amount (often <1 mol%) of a chiral catalyst to impart stereoselectivity to the product formed. Though catalytic asymmetric hydrogenation is not a new reaction type, there remain many substrate classes for which it is ineffective. The present thesis describes efforts to extend the reaction to some of these substrates classes. Some of the products synthesized in these studies may eventually find use as building blocks for the production of chiral pharmaceuticals, agrochemicals, or flavouring or colouring agents. However, the primary and immediate aim of this thesis was to develop and demonstrate new catalysts that are rapid and effective in the asymmetric hydrogenation of a broad range of compounds.

    Paper I describes the design and construction of two new, related chiral iridium compounds that are catalysts for asymmetric hydrogenation. They each contain an N,P-donating phosphinooxazoline ligand that is held together by a rigid bicyclic unit. One of these iridium compounds catalyzed the asymmetric hydrogenation of acyclic aryl imines, often with very good enantioselectivities. This is particularly notable because acyclic imines are difficult to reduce with useful enantioselectivity. The second catalyst was useful for the asymmetric hydrogenation of two aryl olefins. In Paper II, the class of catalysts introduced into Paper I is expanded to include many more related compounds, and these are also applied to the asymmetric hydrogenation of prochiral imines and olefins. By studying a range of related catalysts that differ in a single attribute, we were able to probe how different parts of the catalyst affect the yield and selectivity of the hydrogenation reactions.

    Whereas iridium catalysts had been applied to the asymmetric hydrogenation of imines and largely unfunctionalized olefins prior to this work (with varied degrees of success), they had not been used to reduce fluoroolefins. Their hydrogenation, which is discussed in Paper III, was complicated by concomitant defluorination to yield non-halogenated alkanes. To combat this problem, several iridium-based hydrogenation catalysts were applied to the reaction. Two catalysts stood out for their ability to produce chiral fluoroalkanes in good enantioselectivity while minimizing the defluorination reaction, and one of these bore a phosphinooxazoline ligand of the type described in Papers I and II.

    Enol phosphinates are another class of olefins that had not previously been subjected to iridium-catalyzed asymmetric hydrogenation. They do, however, constitute an attractive substrate class, because the product chiral alkyl phosphinates can be transformed into chiral alcohols or chiral phosphines with no erosion of enantiopurity. Iridium complexes of the phosphinooxazoline ligands described in Papers I and II were extremely effective catalysts for the asymmetric hydrogenation of enol phosphinates. They produced alkyl phosphinates from di- and trisubstituted enol phosphinate, β-ketoester-derived enol phosphinates, and even purely alkyl-substituted enol phopshinates, in very high yields and enantioselectivities.

    List of papers
    1. Application of Phosphine-Oxazoline Ligands in Ir-Catalyzed Asymmetric Hydrogenation of Acyclic Aromatic N-Arylimines
    Open this publication in new window or tab >>Application of Phosphine-Oxazoline Ligands in Ir-Catalyzed Asymmetric Hydrogenation of Acyclic Aromatic N-Arylimines
    2004 In: Organic Letters, Vol. 6, no 21, p. 3825-3827Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-97350 (URN)
    Available from: 2008-05-13 Created: 2008-05-13Bibliographically approved
    2. Hydrogenation of Imines and Olefins Using Phosphine-Oxazoline Iridium Complexes as Catalysts
    Open this publication in new window or tab >>Hydrogenation of Imines and Olefins Using Phosphine-Oxazoline Iridium Complexes as Catalysts
    2006 In: Chemistry-A European Journal, Vol. 12, no 8, p. 2318-2328Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-97351 (URN)
    Available from: 2008-05-13 Created: 2008-05-13Bibliographically approved
    3. Iridium-Catalyzed Asymmetric Hydrogenation of Fluorinated Olefins Using N,P-Ligands: A struggle with hydrogenolysis and selectivity
    Open this publication in new window or tab >>Iridium-Catalyzed Asymmetric Hydrogenation of Fluorinated Olefins Using N,P-Ligands: A struggle with hydrogenolysis and selectivity
    2007 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 129, no 15, p. 4536-4537Article in journal (Refereed) Published
    Abstract [en]

    To broaden the substrate scope of asymmetric iridium-catalyzed hydrogenation, fluorine-functionalized olefins were synthesized and hydrogenated with iridium complexes. Preliminary results showed high levels of fluorine elimination together with low selectivity. The loss of vinylic fluorine at first seemed difficult to handle, but further studies revealed that a catalyst with an azanorbornyl scaffold in the ligand gave more promising results. With this in mind, a new ligand was developed. This gave among the best results published to date for fluorine asymmetric hydrogenation, yielding high conversion and very high ee's with very little fluorine elimination. Further increasing the selectivity, the trials also revealed that tetrasubstituted fluorine-containing olefins can be hydrogenated with high ee's, despite that this class of compounds has usually shown low reactivity in this reaction type.

    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-97352 (URN)10.1021/ja0686763 (DOI)000245739700016 ()17375924 (PubMedID)
    Available from: 2008-05-13 Created: 2008-05-13 Last updated: 2017-12-14Bibliographically approved
    4. Asymmetric Hydrogenation of Di and Trisubstituted Enol Phosphinates with N,P-Ligated Iridium Complexes
    Open this publication in new window or tab >>Asymmetric Hydrogenation of Di and Trisubstituted Enol Phosphinates with N,P-Ligated Iridium Complexes
    2008 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 130, no 16, p. 5595-5599Article in journal (Refereed) Published
    Abstract [en]

    The iridium-catalyzed asymmetric hydrogenation of various di- and trisubstituted enol phosphinates has been studied. Excellent enantioselectivities (up to >99% ee) and full conversion were observed for a range of substrates with both aromatic and aliphatic side chains. Enol phosphinates are structural analogues of enol acetates, and the hydrogenated alkyl phosphinate products can easily be transformed into the corresponding alcohols with conservation of stereochemistry. We have also hydrogenated, in excellent ee, several purely alkyl-substituted enol phosphinates, producing chiral alcohols that are difficult to obtain highly enantioselectively from ketone hydrogenations.

    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-97722 (URN)10.1021/ja711372c (DOI)000255041400050 ()
    Available from: 2008-11-11 Created: 2008-11-11 Last updated: 2017-12-14Bibliographically approved
  • 222. Dobrovolsky, Vasily N.
    et al.
    Bowyer, John F.
    Pabarcus, Michael K.
    Heflich, Robert H.
    Williams, Lee D.
    Doerge, Daniel R.
    Arvidsson, Björn
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Analytisk kemi.
    Bergquist, Jonas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Analytisk kemi.
    Casida, John E.
    Effect of arylformamidase (kynurenine formamidase) gene inactivation in mice on enzymatic activity, kynurenine pathway metabolites and phenotype2005In: Biochimica et Biophysica Acta, no 1724, p. 163-172Article in journal (Refereed)
    Abstract [en]

    The gene coding for arylformamidase (Afmid, also known as kynurenine formamidase) was inactivated in mice through the removal of a shared bidirectional promoter region regulating expression of the Afmid and thymidine kinase (Tk) genes. Afmid/Tk-deficient mice are known to develop sclerosis of glomeruli and to have an abnormal immune system. Afmid-catalyzed hydrolysis of N-formyl-kynurenine is a key step in tryptophan metabolism and biosynthesis of kynurenine-derived products including kynurenic acid, quinolinic acid, nicotinamide, NAD, and NADP. A disruption of these pathways is implicated in neurotoxicity and immunotoxicity. In wild-type (WT) mice, Afmid-specific activity (as measured by formyl-kynurenine hydrolysis) was 2-fold higher in the liver than in the kidney. Formyl-kynurenine hydrolysis was reduced by ~50% in mice heterozygous (HZ) for Afmid/Tk and almost completely eliminated in Afmid/Tk knockout (KO) mice. However, there was 13% residual formyl-kynurenine hydrolysis in the kidney of KO mice, suggesting the existence of a formamidase other than Afmid. Liver and kidney levels of nicotinamide plus NAD/NADP remained the same in WT, HZ and KO mice. Plasma concentrations of formyl-kynurenine, kynurenine, and kynurenic acid were elevated in KO mice (but not HZ mice) relative to WT mice, further suggesting that there must be enzymes other than Afmid (possibly in the kidney) capable of metabolizing formyl-kynurenine into kynurenine. Gradual kidney deterioration and subsequent failure in KO mice is consisten with high levels of tissue-specific Afmid expression in the kidney of WT but not KO mice. On this basis, the most significant function of the kynurenine pathway and Afmid in mice may be in eliminating toxic metabolites and to a lesser extent in providing intermediates for other processes.

  • 223.
    Drevin, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Determination of Ligand Concentration in Liquid Chromatography Media for Protein Purification1994Licentiate thesis, monograph (Other academic)
  • 224. Dybala-Defratyka, Agnieszka
    et al.
    Rostkowski, Michal
    Matsson, Olle
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry II. Organisk kemi.
    Westaway, Kenneth C.
    Paneth, Piotr
    A New Interpretation of Chlorine Leaving Group Kinetic Isotope Effects; A Theoretical Approach2004In: J. Org. Chem., Vol. 69, p. 4900-4905Article in journal (Refereed)
    Abstract [en]

    The chlorine leaving group kinetic isotope effects (KIEs) for the SN2 reactions between methyl chloride and a wide range of anionic, neutral, and radical anion nucleophiles were calculated in the gas phase and, in several cases, using a continuum solvent model. In contrast to the expected linear dependence of the chlorine KIEs on the Ca-CI bond order in the transition state, the KIEs fell in a very small range (1.0056-1.0091), even though the Ca-CI transition state bond orders varied widely from approximately 0.32 to 0.78, a range from reactant-like to very product-like. This renders chlorine KIEs, and possibly other leaving-group KIEs, less useful for studies of reaction mechanisms than commonly assumed. A partial explanation for this unexpected relationship between the Ca-CI transition state bond order and the magnitude of the chlorine KIE is presented.

  • 225.
    Edgren, E.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Enblad, P.
    Grenvik, Å.
    Lilja, A.
    Valind, S.
    Wiklund, L.
    Hedstrand, U.
    Stjernström, H.
    Persson, L., Pontén, U.
    Långström, B.
    Cerebral blood flow and metabolism after cardiopulmonary resucitation. A pathophysiologic and prognostic positron emission tomography pilot study.2003In: Resuscitation, Vol. 57, no 228, p. 161-170Article in journal (Refereed)
  • 226.
    Edström, K
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Herranen, M
    Thermal stability of the HOPG/liquid electrolyte interphase studied by in situ electrochemical atomic force microscopy2000In: JOURNAL OF THE ELECTROCHEMICAL SOCIETY, ISSN 0013-4651, Vol. 147, no 10, p. 3628-3632Article in journal (Refereed)
    Abstract [en]

    In situ atomic force microscopy (AFM) was used to follow temperature-dependent morphological changes at a highly oriented pyrolytic graphite (HOPG)/electrolyte interface. Cyclic voltammetry was performed on an HOPG crystal covered with an electrolyte [1 M

  • 227.
    Eilers, Gerriet
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Molecular Approaches to Photochemical Solar Energy Conversion: Towards Synthetic Catalysts for Water Oxidation and Proton Reduction2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A molecular system capable of photoinduced water splitting is an attractive approach to solar energy conversion. This thesis deals with the functional characterization of molecular building blocks for the three principal functions of such a molecular system: Photoinduced accumulative charge separation, catalytic water oxidation, and catalytic proton reduction.

    Systems combining a ruthenium-trisbipyridine photosensitizer with multi-electron donors in form of dinuclear ruthenium or manganese complexes were investigated in view of the rate constants of electron transfer and excited state quenching. The kinetics were studied in the different oxidation states of the donor unit by combination of electrochemistry and time resolved spectroscopy. The rapid excited state quenching by the multi-electron donors points to the importance of redox intermediates for efficient accumulative photooxidation of the terminal donor.

    The redox behavior of manganese complexes as mimics of the water oxidizing catalyst in the natural photosynthetic reaction center was studied by electrochemical and spectroscopic methods. For a dinuclear manganese complex ligand exchange reactions were studied in view of their importance for the accumulative oxidation of the complex and its reactivity towards water. With the binding of substrate water, multiple oxidation in a narrow potential range and concomitant deprotonation of the bound water it was demonstrated that the manganese complex is capable of mimicking multiple aspects of photosynthetic water oxidation.

    A dinuclear iron complex was investigated as biomimetic proton reduction catalyst. The complex structurally mimics the active site of the iron-only hydrogenase enzyme and was designed to hold a proton on the bridging ligand and a hydride on the iron centers. Thermodynamics and kinetics of the protonation reactions and the electrochemical behavior of the different protonation states were studied in view of their potential catalytic performance.

    List of papers
    1. Iron hydrogenase active site mimic holding a proton and a hydride
    Open this publication in new window or tab >>Iron hydrogenase active site mimic holding a proton and a hydride
    Show others...
    2006 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 5, p. 520-522Article in journal (Refereed) Published
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-95871 (URN)
    Available from: 2007-05-04 Created: 2007-05-04 Last updated: 2017-12-14
    2. Ligand versus metal protonation of an iron hydrogenase active site mimic
    Open this publication in new window or tab >>Ligand versus metal protonation of an iron hydrogenase active site mimic
    Show others...
    2007 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 13, no 25, p. 7075-7084Article in journal (Refereed) Published
    Abstract [en]

    The protonation behavior of the iron hydrogenase active-site mimic [Fe2(u-adt)(CO)4(PMe3)2] (1; adt=N-benzyl-azadithiolate) has been investigated by spectroscopic, electrochemical, and computational methods. The combination of an adt bridge and electron-donating phosphine ligands allows protonation of either the adt nitrogen to give [Fe2(μ-Hadt)(CO)4(PMe3)2]+ ([1H]+), the Fe-Fe bond to give [Fe2-(μ-adt)(μ-H)(CO)4(PMe3)2]+ ([1Hy]+), or both sites simultaneously to give [Fe2(μ-Hadt)(μ-H)(CO)4(PMe3)2]2+ ([1HHy]2+). Complex 1 and its protonation products have been characterized in acetonitrile solution by IR, 1H, and 31PNMR spectroscopy. The solution structures of all protonation states feature a basal/basal orientation of the phosphine ligands, which contrasts with the basal/apical structure of 1 in the solid state. Density functional calculations have been performed on all protonation states and a comparison between calculated and experimental spectra confirms the structural assignments. The ligand protonated complex [1H]+ (pKa =12) is the initial, metastable protonation product while the hydride [1Hy]+ (pKa=15) is the thermodynamically stable singly protonated form. Tautomerization of cation [1H]+ to [1Hy]+ does not occur spontaneously. However, it can be catalyzed by HCl (k=2.2M-1s-1), which results in the selective formation of cation [1Hy]+. The protonations of the two basic sites have strong mutual effects on their basicities such that the hydride (pKa=8) and the ammonium proton (pKa=5) of the doubly protonated cationic complex [1HHy]2+ are considerably more acidic than in the singly protonated analogues. The formation of dication [1HHy]2+ from cation [1H]+ is exceptionally slow with perchloric or trifluoromethanesulfonic acid (k= 0.15 M-1s-1), while the dication is formed substantially faster (k > 102 M-1 s-1) with hydrobromic acid. Electrochemically, 1 undergoes irreversible reduction at -2.2V versus ferrocene, and this potential shifts to -1.6, - 1.1, and -1.0 V for the cationic complexes [1H]+, [1Hy]+, and [1HHy]2+, respectively, upon protonation. The doubly protonated form [1HHy]2+ is reduced at less negative potential than all previously reported hydrogenase models, although catalytic proton reduction at this potential is characterized by slow turnover.

    Keywords
    density functional calculations, electrochemistry, enzyme models, hydride ligands, tautomerism
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-95872 (URN)10.1002/chem.200700019 (DOI)000249294300005 ()17566128 (PubMedID)
    Available from: 2007-05-04 Created: 2007-05-04 Last updated: 2017-12-14Bibliographically approved
    3. Synthesis and characterization of dinuclear ruthenium complexes covalently linked to Ru(II) tris-bipyridine: an approach to mimics of the donor side of photosystem II
    Open this publication in new window or tab >>Synthesis and characterization of dinuclear ruthenium complexes covalently linked to Ru(II) tris-bipyridine: an approach to mimics of the donor side of photosystem II
    Show others...
    2005 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 11, no 24, p. 7305-7314Article in journal (Refereed) Published
    Abstract [en]

    The structural rearrangements triggered by oxidation of the dinuclear Mn complex [Mn2(bpmp)(u-OAc)2]+ (bpmp = 2,6-bis[bis(2-pyridylmethyl)amino]methyl-4-methylphenol anion) in the presence of water have been studied by combinations of electrochemistry with IR spectroscopy and with electrospray ionization mass spectrometry (ESI-MS). The exchange of acetate bridges for water (D2O) derived ligands in different oxidation states could be monitored by mid-IR spectroscopy in CD3CN-D2O mixtures following the Vas(C-O) bands of bound acetate at 1594.4 cm-1 (II,II), 1592.0 cm-1 (II,III) and 1586.5 cm-1 (III,III). Substantial loss of bound acetate occurs at much lower water content (<0.5% v/v) in the III,III state than in the II,II and II,III states (>10%). The ligand-exchange reactions do not initially reduce the overall charge of the complex but facilitate further oxidation by proton-coupled electron transfer as the water-derived ligands are increasingly deprotonated in higher oxidation states. In the IR spectra deprotonation could be followed by the formation of acetic acid (DOAc, ~1725 cm-1, V(C-O)) from the released acetate (1573.6 cm-1, Vas(C-O)). By the on-line combination of an electrochemical flow cell with ESI-MS several product complexes could be identified. A di-u-oxo bridged III,IV dimer [Mn2(bpmp)(u-O)2]2+ (m/z 335.8) can be generated at potentials below the III,III/II,III couple of the di-u-acetato complex (0.61 V Vs. ferrocene). The ligand-exchange reactions allow for three metal-centered oxidation steps to occur from II,II to III,IV in a potential range of only 0.5 V, explaining the formation of a spin-coupled III,IV dimer by photo-oxidation with [Ru(bpy)3]3+ in previous EPR studies.

    Keywords
    electrochemistry, electron transfer, mixed-valent compounds, ruthenium cluster, sensitizers
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-95873 (URN)10.1002/chem.200500592 (DOI)16163754 (PubMedID)
    Available from: 2007-05-04 Created: 2007-05-04 Last updated: 2017-12-14
    4. Ligand exchange upon oxidation of a dinuclear Mn complex - Detection of structural changes by FT-IR spectroscopy and ESI-MS.
    Open this publication in new window or tab >>Ligand exchange upon oxidation of a dinuclear Mn complex - Detection of structural changes by FT-IR spectroscopy and ESI-MS.
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    2005 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, no 6, p. 1033-1041Article in journal (Refereed) Published
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-95874 (URN)
    Available from: 2007-05-04 Created: 2007-05-04 Last updated: 2017-12-14
    5. Synthesis and redox properties of a [meso-tris(4-nitrophenyl) corrolato]Mn(III) complex.
    Open this publication in new window or tab >>Synthesis and redox properties of a [meso-tris(4-nitrophenyl) corrolato]Mn(III) complex.
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    2005 (English)In: Journal of Porphyrins and Phthalocyanines, ISSN 1088-4246, E-ISSN 1099-1409, no 9(6), p. 379-386Article in journal (Refereed) Published
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-95875 (URN)
    Available from: 2007-05-04 Created: 2007-05-04 Last updated: 2017-12-14
  • 228.
    Eilers, Gerriet
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    Zettersten, Camilla
    Nyholm, Leif
    Hammarström, Leif
    Lomoth, Reiner
    Ligand exchange upon oxidation of a dinuclear Mn complex - Detection of structural changes by FT-IR spectroscopy and ESI-MS.2005In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, no 6, p. 1033-1041Article in journal (Refereed)
  • 229. Ekegren, J. K.
    et al.
    Modin, S. A.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Alonso, D. A.
    Andersson, P. G.
    Multigram scale synthesis of auselful aza-Diels-Alder adduct in a one-step procedure2002In: Tetrahedron: Asymmetry, ISSN 0957-4166, Vol. 13, no 4, p. 447-449Article in journal (Refereed)
  • 230.
    Ekegren, Jenny
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Synthesis of New Chiral N, S- and N, O-Ligands. Evaluation in Asymetric Transfer Hydrogenation2002Licentiate thesis, monograph (Other scientific)
  • 231.
    Ekegren, Jenny
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Modin, Stefan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Alonso, Diego
    Andersson, Pher
    Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Multigram scale synthesis of a useful aza-Diels-Alder adduct in a one-step procedure2002In: Tetrahedron Asymmetry, no 13, p. 447-449Article in journal (Refereed)
  • 232. Ekegren, Jenny
    et al.
    Roth, Peter
    Källström, Klas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Tarnai, Tibor
    Andersson, Pher
    Synthesis and evaluation of N,S-compounds as chiral ligands for transfer hydrogenation of acetophenone.2003In: Organic & Biomolecular Chemistry, ISSN 1477-0520, Vol. 1, no 2, p. 358-366Article in journal (Refereed)
  • 233.
    Ekegren, Jenny
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Roth, Peter
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Källström, Klas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Tarnai, Tibor
    Andersson, Pher
    Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Synthesis and evaluation of N,S-compounds as chiral ligands for transfer hydrogenation of acetophenone2003In: Org. Biomol. Chem, no 1, p. 358-366Article in journal (Refereed)
  • 234.
    Ekegren J.K, Roth P, Källström K, Tarnai T, Andersson P.G
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Synthesis and Evaluation of N,S-Ligands for Transfer Hydrogenation of Prochiral Ketones2003In: Org. Biomol. Chem., no 1, p. 358-Article in journal (Other scientific)
  • 235.
    El-Nahas, A
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Johansson, M
    Ottosson, H
    Reverse Si=C Bond Polarization as a Means for Stabilization of Silabenzenes: A Computational Investigation2003In: Organometallics, no 22, p. 5556-5566Article in journal (Refereed)
  • 236.
    El-Sayed, I .
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Guliashvili, T.
    Hazell, R.
    Gogoll, A.
    Ottosson, H.
    Evidence for Formation of Silenes Strongly Influenced by Reversed Si=C Bond Polarity2002In: Organic LettersArticle in journal (Other scientific)
  • 237. El-Sayed, Ibrahim
    et al.
    Guliashvili, Tamaz
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry, Organic Chemistry.
    Hazell, Rita
    Gogoll, Adolf
    Ottosson, Henrik
    Evidence for Formation of Silenes Strongly Influenced by Reversed Si=C Bond Polarity2002In: Organic Letters, ISSN 1523-7060, Vol. 4, no 11, p. 1915-1918Article in journal (Refereed)
  • 238.
    El-Seedi, Hesham R
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Gohil, Suresh
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    Perera, Premila
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Torssell, Kurt B G
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Bohlin, Lars
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Division of Pharmacognosy.
    Cyclopeptide alkaloids from Heisteria nitida1999In: Phytochemistry, ISSN 0031-9422, E-ISSN 1873-3700, Vol. 52, no 8, p. 1739-1744Article in journal (Refereed)
  • 239. Enander, Karin
    et al.
    Aili, D.
    Baltzer, Lars
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry II.
    Lundström, I.
    Liedberg, B.
    Alpha helix-inducing dimerization of synthetic polypeptide scaffolds on gold2005In: Langmuir, no 21, p. 2480-2487Article in journal (Refereed)
  • 240.
    Enander, Karin
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry II.
    Dolphin, G. T.
    Baltzer, Lars
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry II.
    Designed functionalized helix-loop-helix motifs that bind human Carbonic Anhydrase II- a new class of synthetic receptor molecules2004In: J. Am. Chem. Soc., no 126, p. 4464-4465Article in journal (Refereed)
  • 241.
    Enander, Karin
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry II.
    Dolphin, G.T.
    Liedberg, B.
    Lundström, I.
    Baltzer, Lars
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry II.
    A versatile polypeptide platform for intergrated recognition and reporting - affinity arrays for protein - ligand interaction analysis2004In: Chem. Eur. J., no 10, p. 2375-2385Article in journal (Refereed)
  • 242.
    Enblad P., Frykholm P., Valtysson J., Silander H C., Andersson J., Fasth K J., Watanabe Y., Långström B., Hillered L., Persson L.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Middle cerebral artery occlusion and reperfusion in primates monitored by microdialysis and sequential positron emission tomography2001In: Stroke, no 32 (7), p. 1574-80Article in journal (Refereed)
  • 243.
    Engler, H.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    Blomquist, G.
    Nordberg, A.
    Wall, A.
    Estrada, S.
    Koivisto, P.
    Savitcheva, I.
    Sandell, J.
    Barletta, J.
    Antoni, Gunnar
    Bergström, M.
    Långström, B.
    PIB: a new tracer for imaging amyloid-b deposition in vivo. Comparison with FDG2003In: AMI, Madrid Spanien, 2003Conference paper (Other academic)
  • 244.
    Engler, H
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Lundberg, P.O
    Ekbom, K
    Nennesmo, I
    Nilsson, A
    Bergström, M
    Tsukada, H
    Hartvig, P
    Långström, B.
    Multitracer study with positron emission tomgraphy in Crutzfeldt-jakob disease2003In: Eur. J. Nucl. Med., no 30, p. 85-95Article in journal (Other scientific)
  • 245.
    Engman, L.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Antioxidative Properties of Organotellurium Compounds2001Article in journal (Other scientific)
  • 246.
    Engman L, Al-Maharik N, MacNaughton M, Birmingham A, Powis G
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Thioredoxin Reductase and Cancer Cell Growth Inhibition by Organotellurium Antioxidants2003In: Anti-Cancer Drugs, no 14, p. 153-Article in journal (Other scientific)
  • 247.
    Engman L., Kanada T., Gallegos A., Williams R., Powis G.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Water-soluble organotellurium compounds inhibit thioredoxin reductase and the growth of human cancer cells2001In: Anti-Cancer Drug Design, Vol. 2000, no 1, p. 330-Article in journal (Refereed)
  • 248.
    Engman, L
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Kanda, T
    Gallegos, A
    Williams, R
    Powis, G
    Water-soluble organotellurium compounds inhibit thioredoxin reductase and the growth of human cancer cells2000In: ANTI-CANCER DRUG DESIGN, ISSN 0266-9536, Vol. 15, no 5, p. 323-330Article in journal (Refereed)
    Abstract [en]

    The thioredoxin system (NADPH, thioredoxin reductase/ thioredoxin) is important for cancer cell growth and inhibition of apoptosis and presents an attractive target for anticancer drug development. Thioredoxin reductase is a selenocysteine-containing flav

  • 249.
    Engman, L.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry.
    Kania, I.
    Oleksyn, B.J.
    Sliwinski, J.
    Wojton, A.J.
    Intermolecular Interactions in the Crystalline State of some Organotellurium Antioxidants2002Article in journal (Other scientific)
  • 250.
    Engman, Lars
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Organic Chemistry.
    Al-Maharik, Nawaf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Organic Chemistry.
    McNaughton, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Organic Chemistry.
    Birmingham, A
    Uppsala University.
    Powis, G.
    Uppsala University.
    Thioredoxin Reductase and Cancer Cell Growth Inhibition by Organotellurium Compounds that could be Selectively Incorporated into Tumor Cells2003In: Bioorganic & Medicinal Chemistry, ISSN 0968-0896, E-ISSN 1464-3391, Vol. 11, no 23, p. 5091-5100Article in journal (Refereed)
    Abstract [en]

    The thioredoxins are small ubiquitous redox proteins with the conserved redox catalytic sequence-Trp-Cys-Gly-Pro-Cys-Lys, where the Cys residues undergo reversible NADPH dependent reduction by selenocysteine containing flavoprotein thioredoxin reductases. Thioredoxin expression is increased in several human primary cancers including lung, colon, cervix, liver, pancreatic, colorectal and squamous cell cancer. The thioredoxin/thioredoxin reductase pathway therefore provides an attractive target for cancer drug development. Organotellurium steroid, lipid, amino acid, nucleic base, and polyamine inhibitors were synthesized on the basis that they might be selectively or differentially incorporated into tumor cells. Some of the newly prepared classes of tellurium-based inhibitors (lipid-like compounds 3b and 3e, amino acid derivative 5b, nucleic base derivative 8b, and polyamine derivatives 14a and 14b) inhibited TrxR/Trx and cancer cell growth in culture with IC(50) values in the low micromolar range.

2345678 201 - 250 of 1047
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