Evidence for covalent binding between copper ions and cyclodextrin cavity:a vibrational circular dichroism study

Vibrational absorption and circular dichroism (VCD) spectra were obtained f or parent cyclodextrins, hydroxyl deuterated alpha-cyclodextrin, cyclodextr in-copper complexes, and for the cyclodextrin inclusion complexes with Meth yl Orange, methyloxirane, 1-propanol, and substituted cyclohexanones, in th e solution phase. Changes in the VCD spectra, reflecting perturbations of c yclodextrin cavity, were found in the case of an inclusion complex with Met hyl Orange, but for the remaining inclusion complexes measurable changes in VCD were not found. Significant changes observed in the VCD spectra of cyc lodextrin-copper complexes suggest that the covalent binding of copper ions to the hydroxyl groups of cyclodextrin is involved. (C) 2000 Elsevier Scie nce Ltd. All rights reserved.