Inclusion complexes of cyclodextrins with nitroxide-based spin probes in aqueous solutions.
Formation of inclusion complexes between several cyclodextrin derivatives and TEMPO and DOXYL-based spin probes was studied by EPR spectroscopy. Competition between alkyl chains and nitroxide functionalities for cyclodextrin cavities leads to different types of complexation. Long alkyl chains in amphiphilic spin probes interact preferentially with cyclodextrins, and TEMPO units in such molecules are unaffected by complexation. DOXYL-type spin probes however form stronger complexes with cyclodextrins; this complexation changes hyperfine splitting and tumbling rate of the nitroxide group. Comparison of EPR spectra of free cyclodextrin and cyclodextrin-based polymeric nanocapsules made it possible to assess the tumbling of the spin probe inside the cyclodextrin units without the contribution of the tumbling of the whole complex.
Ionita
Gabriela
G
Laboratory of Quantum Chemistry and Molecular Structure, Institute of Physical Chemistry Ilie Murgulescu, Splaiul Independentei 202, Bucharest, 060021, Romania. gabi2ionita@yahoo.com
Caragheorgheopol
Agneta
A
Caldararu
Horia
H
Jones
Leonie
L
Chechik
Victor
V
D000388:Air; D003432:Cross-Linking Reagents / Q000737:chemistry; D003497:Cyclic N-Oxides / Q000737:chemistry; D003505:Cyclodextrins / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D057927:Hydrophobic and Hydrophilic Interactions; D053769:Nanocapsules / Q000737:chemistry; D009589:Nitrogen Oxides / Q000737:chemistry*; D010084:Oxidation-Reduction; D012995:Solubility; D012996:Solutions; D013113:Spin Labels; D014867:Water / Q000737:chemistry*
D003432:Cross-Linking Reagents; D003497:Cyclic N-Oxides; D003505:Cyclodextrins; D004220:Disulfides; D053769:Nanocapsules; D009589:Nitrogen Oxides; D012996:Solutions; D013113:Spin Labels; D014867:Water; C039900:nitroxyl; C003959:TEMPO