The stoichiometry, geometry, stability, and solubility of the inclusion complexes of melatonin (MLT) with native cyclomaltooligosaccharides (Î±-, Î²- or Î³-cyclodextrins, CDs) are determined experimentally by high-resolution NMR spectroscopy, calorimetric and solubility measurements, and mass spectrometry. The observed differences are discussed in terms of molecular recognition expression of the host-guest (h-g) interactions within the hydrophobic CDs cavities of different size. The 1:1 h-g stoichiometry in water solution prevails at low CD concentrations; the trend to form higher order associations is observed at increasing CD concentrations. The stability order Î²-CD>Î³-CD>Î±-CD for the complexes in water solution and Î²-CD>Î±-CD>Î³-CD for the protonated or alkali-cationated complexes in the gas phase are rationalized on the grounds of the structural data from NMR spectroscopy and of the thermodynamic parameters from calorimetric measurements. Â© 2002 Elsevier Science Ltd. All rights reserved.
|Numero di pagine||12|
|Stato di pubblicazione||Published - 2002|
All Science Journal Classification (ASJC) codes