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EPR Studies of the Binding Properties, Guest Dynamics, and Inner‐Space Dimensions of a Water‐Soluble Resorcinarene Capsule
Author(s) -
Ayhan Mehmet Menaf,
Casano Gilles,
Karoui Hakim,
Rockenbauer Antal,
Monnier Valérie,
Hardy Micaël,
Tordo Paul,
Bardelang David,
Ouari Olivier
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201502212
Subject(s) - electron paramagnetic resonance , resorcinarene , chemistry , hydrogen bond , steric effects , crystallography , molecular dynamics , computational chemistry , stereochemistry , nuclear magnetic resonance , molecule , organic chemistry , physics
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 ( K a ) 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.