title: Studying supramolecular assemblies by ESEEM spectroscopy: inclusion complexes of cyclodextrins.
abstract: Electron spin-echo envelope modulation (ESEEM) spectroscopy was used to investigate intramolecular and intermolecular complexes of cyclodextrins (CDs) with a nitroxide group. The interaction with solvent molecules (D(2)O) was followed through the (2)H modulation depth. Competition experiments with adamantane-type guests were used to confirm complexation. The shielding of the nitroxide group from solvent upon inclusion into a CD cavity made this technique more sensitive to complexation than cw EPR spectroscopy. ESEEM analysis of a series of CDs mono and bis spin-labeled on the primary rim of the cavity showed that only one compound formed a self-inclusion complex. This suggests that significant linker length/flexibility is required for formation of inclusion complexes in functionalized CDs. DEER (double electron-electron resonance) experiments confirmed that the self-inclusion complex of the spin-labeled CD was intra- rather than intermolecular.
authors.affiliation: Institute of Physical Chemistry, 202 Splaiul Independentei, Bucharest, Romania.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Ionita
authors.forename: Marc
authors.initials: M
authors.lastname: Florent
authors.forename: Daniella
authors.initials: D
authors.lastname: Goldfarb
authors.forename: Victor
authors.initials: V
authors.lastname: Chechik