title: EPR Studies of the Binding Properties, Guest Dynamics, and Inner-Space Dimensions of a Water-Soluble Resorcinarene Capsule.
abstract: Nitroxide free radicals have been used to study the inner space of one of Rebek's water-soluble capsules. EPR and (1) H NMR spectroscopy, ESI-MS, and DFT calculations showed a preference for the formation of 1:2 complexes. EPR titrations allowed us to determine binding constants (Ka ) in the order of 10(7)  M(-2) . EPR spectral-shape analysis provided information on the guest rotational dynamics within the capsule. The interplay between optimum hydrogen bonding upon capsule formation and steric strain for guest accommodation highlights some degree of flexibility for guest inclusion, particularly at the center of the capsule where the hydrogen bond seam can be barely distorted or slightly disturbed.
authors.affiliation: Aix-Marseille Université, CNRS, Institut de Chimie Radicalaire, UMR 7273, 13013 Marseille (France).|Department of Chemistry, Gebze Technical University, P.K.:141, 41400 Gebze, Kocaeli (Turkey).
authors.forename: Mehmet Menaf
authors.initials: MM
authors.lastname: Ayhan
authors.affiliation: Aix-Marseille Université, CNRS, Institut de Chimie Radicalaire, UMR 7273, 13013 Marseille (France).
authors.forename: Gilles
authors.initials: G
authors.lastname: Casano
authors.affiliation: Aix-Marseille Université, CNRS, Institut de Chimie Radicalaire, UMR 7273, 13013 Marseille (France).
authors.forename: Hakim
authors.initials: H
authors.lastname: Karoui
authors.affiliation: Institute of Materials and Environmental Chemistry, Hungarian Academy of Sciences and, Department of Physics, Budapest University of Technology and Economics, Budafoki ut 8, 1111 Budapest (Hungary).
authors.forename: Antal
authors.initials: A
authors.lastname: Rockenbauer
authors.affiliation: Aix-Marseille Université, CNRS, Spectropole, FR 1739, 13013 Marseille (France).
authors.forename: Valérie
authors.initials: V
authors.lastname: Monnier
authors.affiliation: Aix-Marseille Université, CNRS, Institut de Chimie Radicalaire, UMR 7273, 13013 Marseille (France).
authors.forename: Micaël
authors.initials: M
authors.lastname: Hardy
authors.affiliation: Aix-Marseille Université, CNRS, Institut de Chimie Radicalaire, UMR 7273, 13013 Marseille (France).
authors.forename: Paul
authors.initials: P
authors.lastname: Tordo
authors.affiliation: Aix-Marseille Université, CNRS, Institut de Chimie Radicalaire, UMR 7273, 13013 Marseille (France).
authors.forename: David
authors.initials: D
authors.lastname: Bardelang
authors.affiliation: Aix-Marseille Université, CNRS, Institut de Chimie Radicalaire, UMR 7273, 13013 Marseille (France). olivier.ouari@univ-amu.fr.
authors.forename: Olivier
authors.initials: O
authors.lastname: Ouari
keywords: EPR spectroscopy; capsules; host-guest systems; nitroxides; supramolecular chemistry