Inclusion complexes formed in lanthanide—amino acid—β-cyclodextrin systems

Abstract

Interactions in lanthanide—amino acid—β-cyclodextrin systems (amino acid = tryptophan, phenylalanine; lanthanide = Eu3+, Pr3+) were studied in aqueous solution. An analysis of the chemical shifts observed in the 1H NMR spectra, as well as the ROESY data suggest the possibility for amino acid—lanthanide ion complexes encapsulated in the β-cyclodextrin cavity to form in solution. According to ROESY data, the indole ring of tryptophan and the phenyl group of phenylalanine enter the β-CD cavity from the wide rim side. Coordination with the metal ion occurs through the amino acid carboxyl group.