title: Remarkably stable inclusion complexes with heptakis-[6-deoxy-6-(2-aminoethylsulfanyl)]-beta-cyclodextrin.
abstract: Complexes of heptakis-[6-deoxy-6-(2-aminoethylsulfanyl)]-beta-cyclodextrin (1) and a series of common cyclodextrin guests were studied by NMR, fluorescence spectroscopy, and ITC experiments. NMR conformational analysis shows that the thioethers of 1 are positioned over the hydrophobic cavity of the cyclodextrin, increasing potential hydrophobic interactions with guest molecules. The combination of the increased hydrophobic character, the electrostatic complementarity and a hypothesized conformational change in 1 lead to a complex with the dye 2,6-ANS (5) that is over 2000 times more stable than with the native beta-cyclodextrin. One of the most stable host-guest complexes between a cyclodextrin and a small molecule measured to date was revealed between 1 and lithocholic acid (4) with an association constant of 5.5 x 10(7) M(-1).
authors.affiliation: Department of Chemistry, University of Toronto, Toronto 80 St. George St., Canada.
authors.forename: Rodolfo F
authors.initials: RF
authors.lastname: Gómez-Biagi
authors.forename: Richard B C
authors.initials: RB
authors.lastname: Jagt
authors.forename: Mark
authors.initials: M
authors.lastname: Nitz