THE COMPLEXATION AND CHIRAL SELECTIVITY OF 2-HYDROXYPROPYL-BETA-CYCLODEXTRIN WITH GUEST MOLECULES AS STUDIED BY ELECTROSPRAY MASS-SPECTROMETRY

Electrospray mass spectrometry has been used to study the complexation of 'guest' molecules with a mixture of hydroxypropyl-substituted beta-cyclodextrin derivatives. In all cases studied, the predominant derivative was shown to contain a maximum of seven hydroxypropyl groups, most probably related to alkylation of each of the seven glucose units of the parent beta-cyclodextrin. Chiral selectivity was not observed for D- and L-phenylalanine methyl esters. In contrast D-propranolol and L-tryptophan methyl ester formed stronger complexes than the corresponding L- and D-enantiomers, respectively. Molecular modelling studies were also carried out, in an attempt to identify the factors that can play a part in determining the mechanism of the observed non-covalent interactions.