title: Effect of terbium(III) on the binding of aromatic guests with sodium taurocholate aggregates.
abstract: The effect of binding Tb(3+) to sodium taurocholate aggregates containing polyaromatic hydrocarbon guests was examined using pyrene and 1-ethylnaphthalene as guests that bind to the primary aggregate, and 1-naphthyl-1-ethanol as a secondary aggregate guest. Time-resolved fluorescence quenching studies were used to study the binding site properties, while laser flash photolysis quenching studies provided information on the dynamics of the guest-aggregate system. Both the primary and secondary aggregate binding sites became more compact in the presence of bound Tb(3+), while only the primary aggregate became more accessible to anionic molecules. The binding dynamics for the guest-primary aggregate system became faster when Tb(3+) was bound to the aggregate. In contrast, for the guest-secondary aggregate the presence of Tb(3+) resulted in a small decrease in the dissociation rate constant. The influence of bound Tb(3+) on the primary and secondary bile salt aggregates is significantly different, which affects how these aggregates can be used as supramolecular host systems to modify guest reactivity.
authors.affiliation: Department of Chemistry, University of Victoria, P. O. Box 3065, Victoria, British Columbia V8W 3V6, Canada. tamarapace@gmail.com
authors.forename: Tamara C S
authors.initials: TC
authors.lastname: Pace
authors.forename: Sergio P
authors.initials: SP
authors.lastname: Souza
authors.forename: Hui Ting
authors.initials: HT
authors.lastname: Zhang
authors.forename: Cornelia
authors.initials: C
authors.lastname: Bohne
mesh_terms: D001665:Binding Sites; D007700:Kinetics; D009281:Naphthalenes / Q000737:chemistry; D010782:Photolysis; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry; D011721:Pyrenes / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013656:Taurocholic Acid / Q000737:chemistry*; D013725:Terbium / Q000737:chemistry*; D013997:Time Factors
chemical_list: D009281:Naphthalenes; D011084:Polycyclic Aromatic Hydrocarbons; D011721:Pyrenes; D013725:Terbium; C031721:naphthalene; D013656:Taurocholic Acid; C030984:pyrene