title: Quantitative effects of antihydrophobic agents on binding constants and solubilities in water.
abstract: The effects of urea and of guanidinium chloride on binding constants in water for 6-(4-tert-butylanilino)-naphthalene-2-sulfonate and of bis(p-tert-butylphenyl) phosphate binding to beta-cyclodextrin and to N,N'-bis(6-beta-cyclo-dextrinyl)imidazolium ion have been determined. Their effects on the water solubility of p-tert-butylbenzyl alcohol and p-methylbenzyl alcohol have also been examined. Quantitative correlations show that the effects of these additives, which diminish hydrophobic effects, are similar for release of a tert-butylphenyl group from a cyclodextrin cavity into water or for solubilizing such a group from a second phase. The effects of these agents on the binding constants for double-ended substrates binding to the bis(cyclodextrin) host are much larger than for a simple substrate binding to monomeric cyclodextrin, consistent with additivity of free-energy perturbations. Ethanol also decreases binding in these systems, and increases solubilities, but the quantitative correlations are less straightforward.
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027.
authors.forename: R
authors.initials: R
authors.lastname: Breslow
authors.forename: S
authors.initials: S
authors.lastname: Halfon
mesh_terms: D000438:Alcohols; D000817:Anilino Naphthalenesulfonates; D001665:Binding Sites; D002236:Carbohydrate Conformation; D003505:Cyclodextrins / Q000737:chemistry*; D019791:Guanidine; D006146:Guanidines; D010755:Organophosphates; D012995:Solubility; D014508:Urea; D014867:Water; D047392:beta-Cyclodextrins
chemical_list: D000438:Alcohols; D000817:Anilino Naphthalenesulfonates; D003505:Cyclodextrins; D006146:Guanidines; D010755:Organophosphates; D047392:beta-Cyclodextrins; D014867:Water; C075902:6-(4-tert-butylanilino)naphthalene-2-sulfonate; C075901:bis(tert-butylphenyl) phosphate; D014508:Urea; D019791:Guanidine; C031215:betadex