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  • 1.
    Hamnevik, Emil
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Blikstad, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Norrehed, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Widersten, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Kinetic characterization of Rhodococcus ruber DSM 44541 alcohol dehydrogenase A2014In: Journal of Molecular Catalysis B: Enzymatic, ISSN 1381-1177, E-ISSN 1873-3158, Vol. 99, p. 68-78Article in journal (Refereed)
    Abstract [en]

    An increasing interest in biocatalysis and the use of stereoselective alcohol dehydrogenases in synthetic asymmetric catalysis motivates detailed studies of potentially useful enzymes such as alcohol dehydrogenase A (ADH-A) from Rhodococcus ruber. This enzyme is capable of catalyzing enantio-, and regioselective production of phenyl-substituted α-hydroxy ketones (acyloins) which are precursors for the synthesis of a range of biologically active compounds. In this study, we have determined the enzyme activity for a selection of phenyl-substituted vicinal diols and other aryl- or alkyl-substituted alcohols and ketones. In addition, the kinetic mechanism for the oxidation of (R)- and (S)-1-phenylethanol and the reduction of acetophenone has been identified as an Iso Theorell-Chance (hit and run) mechanism with conformational changes of the enzyme-coenzyme binary complexes as rate-determining for the oxidation of (S)-1-phenylethanol and the reduction of acetophenone. The underlying cause of the 270-fold enantiopreference for the (S)-enantiomer of 1-phenylethanol has been attributed to non-productive binding of the R-enantiomer. We have also shown that it is possible to tune the direction of the redox chemistry by adjusting pH with the oxidative reaction being favored at pH values above 7.

  • 2.
    Norrehed, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Modulation of Molecular Properties: Host–Guest Interactions for Structural Analysis and Chemical Reactions2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis concerns the construction, use and modulation of various host–guest systems, from small bispidines for binding of inorganic ions to bisporphyrin clips for supramolecular systems.

    Small flexible molecules undergo fast conformational movements when in solution. These conformational movements generate time-averaged population-weighted chemical shifts, coupling constants and NOEs when analysed by NMR spectroscopy. A bisporphyrin clip was designed to be used as a host for restriction of conformational movements of small flexible molecules by ditopic metal-ligand binding. Based on conformational analysis in combination with NMR analysis of molecular flexibility in solution (NAMFIS), the relative stereochemistry of flexible alditol-derived diamines containing three or four consecutive stereocentres could be determined.

    To further explore the idea of conformational deconvolution via host–guest binding, two flexible molecular tweezers with photoswitchable moieties were developed. Upon photoswitching cis/trans isomerisation facilitates the opening and closing of these bisporphyrin hosts. A guest molecule could then be exposed to a “catch and stretch” or “catch and release” effect. Preliminary studies have shown that photoisomerisation of the constructed systems is possible without photodecomposition and preliminary binding studies have been conducted.

    Controlled modulation of molecular conformations is of interest especially if the conformational steering activates a unit working as a nucleator in a larger structure or facilitates a reaction. The protonation-triggered modulation of bispidine conformations has been investigated. In addition to previously reported conformations we have observed that upon diprotonation a bispidine derivative can be driven into the unusual boat-boat conformation.

    Finally, the unexpected formation of persistent organic radicals with a cyclophane motif from the reaction of N,N´-diphenyl-1-5-diazacyclooctane and AgBF4 is described. Interestingly, these diradicals exhibit features such as intramolecular π-stacking without lateral displacement and also intramolecular spin pairing.

     

    List of papers
    1. Conformational restriction of flexible molecules in solution by a semirigid bis-porphyrin molecular tweezer
    Open this publication in new window or tab >>Conformational restriction of flexible molecules in solution by a semirigid bis-porphyrin molecular tweezer
    Show others...
    2013 (English)In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 69, no 34, p. 7131-7138Article in journal (Refereed) Published
    Abstract [en]

    A semirigid bis-porphyrin molecular clip with a glycoluril backbone has been synthesized. The clip provides an adaptable molecular cavity for binding of diamines. Binding constants for diamines of 104–107 M−1 are orders of magnitude higher than those for monoamines of 103 M−1, indicating a preference to bidentate binding. NMR studies confirmed that binding of bidentate guests occurs inside the clip. Short- and medium-size acyclic molecular guests are locked into a single, extended conformation, and also guests with longer flexible chains exhibit considerably less conformational mobility than when free in solution. The size of the cavity adapts to the guest size, as indicated by modelling studies and self diffusion constants of the complexes.

    Keywords
    Conformational analysis, NMR spectroscopy, Hosteguest systems, Supramolecular chemistry, Porphyrinoids
    National Category
    Natural Sciences Organic Chemistry
    Research subject
    Chemistry with specialization in Organic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-206036 (URN)10.1016/j.tet.2013.06.013 (DOI)000322098000027 ()
    Funder
    Swedish Research Council
    Available from: 2013-08-26 Created: 2013-08-26 Last updated: 2017-12-06Bibliographically approved
    2. Improved stereochemical analysis of conformationally flexible diamines by binding to a bisporphyrin molecular clip
    Open this publication in new window or tab >>Improved stereochemical analysis of conformationally flexible diamines by binding to a bisporphyrin molecular clip
    2013 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 19, no 43, p. 14631-14638Article in journal (Refereed) Published
    Abstract [en]

    The relative stereochemistry of acyclic diamines with several stereogenic centers has been analyzed by NMR spectroscopy in combination with conformational deconvolution. Binding to a bisporphyrin molecular clip improves the stereochemical assignment significantly. The diamines were synthesized from inexpensive sugar alcohols, and their stable hydrochlorides were quantitatively converted into free bases by treatment with ion-exchange resin.

    Keywords
    configuration determination, conformational analysis, host–guest systems, N ligands, NMR spectroscopy
    National Category
    Natural Sciences Organic Chemistry
    Research subject
    Organic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-206040 (URN)10.1002/chem.201300533 (DOI)000330288400025 ()
    Funder
    Swedish Research Council
    Available from: 2013-08-26 Created: 2013-08-26 Last updated: 2017-12-06Bibliographically approved
    3. Photomodulable bis-porphyrin molecular tweezers for conformational studies of diamine guests
    Open this publication in new window or tab >>Photomodulable bis-porphyrin molecular tweezers for conformational studies of diamine guests
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-206039 (URN)
    Available from: 2013-08-26 Created: 2013-08-26 Last updated: 2014-01-23
    4. Protonation-triggered Conformational Modulation of an N,N´‑Dialkylbispidine: First observation of the elusive boat-boat conformer
    Open this publication in new window or tab >>Protonation-triggered Conformational Modulation of an N,N´‑Dialkylbispidine: First observation of the elusive boat-boat conformer
    2013 (English)In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 11, p. 6292-6299Article in journal (Refereed) Published
    Abstract [en]

    Modulation of the solution conformations of N,N′-bis(benzhydryl)bispidine has been achieved by protonation. Conformers have been characterized by NMR spectroscopy using nuclear Overhauser effects and residual dipolar couplings. In contrast to the preference for the chair–chair conformation for the free base and the monoprotonated species, the diprotonated bispidine is revealed to exist as a mixture of chair–boat and boat–boat conformers. While boat–boat conformers of bispidines have previously not been detected, they are here observed to constitute up to 70% of the bispidine population.

    National Category
    Natural Sciences Organic Chemistry
    Research subject
    Organic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-206042 (URN)10.1039/c3ob41122b (DOI)000324507100010 ()
    Funder
    Swedish Research Council
    Available from: 2013-08-26 Created: 2013-08-26 Last updated: 2017-12-06Bibliographically approved
    5. Synthesis of persistent organic dication diradicals incorporating a cyclophane motif with intramolecular pi-stacking
    Open this publication in new window or tab >>Synthesis of persistent organic dication diradicals incorporating a cyclophane motif with intramolecular pi-stacking
    Show others...
    (English)Article in journal (Other academic) Submitted
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-206043 (URN)
    Available from: 2013-08-26 Created: 2013-08-26 Last updated: 2014-01-23Bibliographically approved
  • 3.
    Norrehed, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Erdélyi, Maté
    Light, Mark E.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Protonation-triggered Conformational Modulation of an N,N´‑Dialkylbispidine: First observation of the elusive boat-boat conformer2013In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 11, p. 6292-6299Article in journal (Refereed)
    Abstract [en]

    Modulation of the solution conformations of N,N′-bis(benzhydryl)bispidine has been achieved by protonation. Conformers have been characterized by NMR spectroscopy using nuclear Overhauser effects and residual dipolar couplings. In contrast to the preference for the chair–chair conformation for the free base and the monoprotonated species, the diprotonated bispidine is revealed to exist as a mixture of chair–boat and boat–boat conformers. While boat–boat conformers of bispidines have previously not been detected, they are here observed to constitute up to 70% of the bispidine population.

  • 4.
    Norrehed, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Johansson, Henrik
    Grennberg, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Improved stereochemical analysis of conformationally flexible diamines by binding to a bisporphyrin molecular clip2013In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 19, no 43, p. 14631-14638Article in journal (Refereed)
    Abstract [en]

    The relative stereochemistry of acyclic diamines with several stereogenic centers has been analyzed by NMR spectroscopy in combination with conformational deconvolution. Binding to a bisporphyrin molecular clip improves the stereochemical assignment significantly. The diamines were synthesized from inexpensive sugar alcohols, and their stable hydrochlorides were quantitatively converted into free bases by treatment with ion-exchange resin.

  • 5.
    Norrehed, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Karlsson, Christoffer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Light, Mark E.
    University of Southampton: Southampton.
    Thapper, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Huang, Ping
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Gogoll, A
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry. Uppsala University.
    Formation of persistent organic diradicals from N,N'-diphenyl-3,7- diazacyclooctanes2019In: Monatshefte fuer Chemie, ISSN 0026-9247, E-ISSN 1434-4475, Vol. 150, no 1, p. 77-84Article in journal (Refereed)
    Abstract [en]

    N,N'-Diphenyl-3,7-diazacyclooctane and structurally related N,N'-diphenylbispidine derivatives react with silver(I) ions in a high-yielding C–C coupling reaction to produce dication–diradical species, with the silver ions serving a double function both as template and as an oxidant. The resulting bis(benzidino)phane derivatives are persistent organic radicals, stable for several months in solution as well as in the solid state, at room temperature and above, as well as being exposed to the atmosphere. The molecular structure features a double-decker cyclophane motif, stabilized by intramolecular π-dimerization of two delocalized benzidinium radical segments. Intermolecular π-dimers are formed in the solid state.

  • 6.
    Norrehed, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Polavarapu, Prasad
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Yang, Wenzhi
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Grennberg, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Conformational restriction of flexible molecules in solution by a semirigid bis-porphyrin molecular tweezer2013In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 69, no 34, p. 7131-7138Article in journal (Refereed)
    Abstract [en]

    A semirigid bis-porphyrin molecular clip with a glycoluril backbone has been synthesized. The clip provides an adaptable molecular cavity for binding of diamines. Binding constants for diamines of 104–107 M−1 are orders of magnitude higher than those for monoamines of 103 M−1, indicating a preference to bidentate binding. NMR studies confirmed that binding of bidentate guests occurs inside the clip. Short- and medium-size acyclic molecular guests are locked into a single, extended conformation, and also guests with longer flexible chains exhibit considerably less conformational mobility than when free in solution. The size of the cavity adapts to the guest size, as indicated by modelling studies and self diffusion constants of the complexes.

1 - 6 of 6
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