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  • 1.
    Grahn, Hans
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Paramagnetic relaxation reagents: nuclear magnetic resonance studies of preferential solvation1986Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The interactions between neutral paramagnetic relaxation reagents (PARR's) and certain aromatic compounds have been studied by 1H and 13 C spin-lattice relaxation time measurements. In media such as cyclohexane and carbon tetrachloride, Cr(acac)3 becomes preferentially solvated by aromatic solutes. The solvation is significantly suppressed in a more interacting solvent like dichloromethane. Paramagnetic induced chemical shifts of the aromatic outer sphere ligand indicate in addition to relaxation data, a preferential orientation caused by dipole-dipole interactions. For benzene or for several alkylated benzenes which have small or no permanent dipole moments, the interaction is electrostatic, i.e. of a dipole-dipole induced type and where the easily polarizable aromatic ring is preferred in the solvation sphere.

    Carbon tetrachloride is shewn to have a specific PARR interaction. If co-ordination number, solution structure etc., are to be determined using weakly interacting substrates, this solvent should be avoided.

    A multivariate statistical approach is also reported, where 13 C electron-nuclear relaxation data and induced shifts of monosubstituted arcmatics have been related to different physical descriptors. Most of the variance in relaxation and shift data is best described by the dipole moment. The results support a dipole-dipole interaction as the preferred solvation mechanism.

    The preferential solvation of several organic substrates with the diamagnetic Co(acac)3 is studied by varying the substrate concentration in cyclohexane. By the use of 59 Co shift, it is shown that proton donating solutes such as chloroform and methanol have a specific solvation. The order of preference is close to that obtained in Cr(acac)3 solutions.

  • 2.
    Hellberg, Sven
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    A multivariate approach to QSAR1986Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Quantitative structure-activity relationships (OSAR) constitute empirical analogy models connecting chemical structure and biological activity. The analogy approach to QSAR assume that the factors important in the biological system also are contained in chemical model systems.

    The development of a QSAR can be divided into subproblems:

    1. to quantify chemical structure in terms of latent variables expressing analogy,

    2. to design test series of compounds,

    3. to measure biological activity and

    4. to construct a mathematical model connecting chemical structure and biological activity.

    In this thesis it is proposed that many possibly relevant descriptors should be considered simultaneously in order to efficiently capture the unknown factors inherent in the descriptors. The importance of multivariately and multipositionally varied test series is discussed. Multivariate projection methods such as PCA and PLS are shown to be appropriate far QSAR and to closely correspond to the analogy assumption.

    The multivariate analogy approach is applied to a beta- adrenergic agents, b haloalkanes, c halogenated ethyl methyl ethers and d four different families of peptides.

  • 3. Långström, Bengt
    et al.
    Antoni, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    Gullberg, Per
    Halldin, Christer
    Någren, Kjell
    Rimland, Annika
    Svärd, Hans
    The synthesis of 1-11C-labelled ethyl, propyl, butyl and isobutyl iodides and examples of alkylation reactions.1986In: Int. J. Appl. Radiat. Isot., Vol. 37, p. 1141-Article in journal (Refereed)
  • 4.
    Rudling, Jan
    et al.
    Research Department, National Board of Occupational Safety and Health .
    Björkholm, Eva
    Research Department, National Board of Occupational Safety and Health .
    Lundmark, Bengt-Ove
    Research Department, National Board of Occupational Safety and Health .
    STORAGE STABILITY OF ORGANIC SOLVENTS ADSORBED ON ACTIVATED CARBON1986In: The Annals of Occupational Hygiene, Vol. 30, no 3, p. 319-327Article in journal (Refereed)
1 - 4 of 4
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