Inclusion complexes of PBN-type nitrone spin traps and their superoxide spin adducts with cyclodextrin derivatives: Parallel determination of the association constants by NMR titrations and 2D-EPR simulations

David Bardelang, Antal Rockenbauer, Hakim Karoui, Jean Pierre Finet, Paul Tordo

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

1H NMR and electron paramagnetic resonance (EPR) titrations were used to determine the association constants of the complexes of α-phenyl-N-tert-butylnitrone (PBN) analogues and their Superoxide spin adducts, respectively, with methylated-β-cyclodextrins. A 1:1 stoichiometry for the nitrones with randomly methylated β-cyclodextrin and 2,6-di-O-methyl-β-cyclodextrin and 1:1 and 1:2 stoichiometries for the corresponding cyclodextrin-nitroxide complexes were observed. After the Superoxide radical spin trapping reaction, EPR titrations afforded the association constants of the corresponding cyclodextrin-nitroxide complexes. Two-dimensional EPR simulations indicated a bimodal inclusion of the nitroxide free radical spin adducts into the cyclodextrins. For all the nitrone-cyclodextrin and nitroxide-cyclodextrin complexes, the association constants were always higher for the nitroxide complexes than for the nitrone complexes. A cooperative system concerning the complexation of the nitroxide spin adduct with a cyclodextrin was evidenced by EPR titrations. The efficiency of the cyclodextrin inclusion technique to trap Superoxide and to resist bioreduction by sodium L-ascorbate was also investigated.

Original languageEnglish
Pages (from-to)10521-10530
Number of pages10
JournalJournal of Physical Chemistry B
Volume109
Issue number20
DOIs
Publication statusPublished - May 26 2005

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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