title: Determination of the kinetics underlying the pKa shift for the 2-aminoanthracenium cation binding with cucurbit[7]uril.
abstract: The binding dynamics of the 2-aminoanthracenium cation (AH(+)) and 2-aminoanthracene (A) with cucurbit[7]uril (CB[7]) was studied using stopped-flow experiments. The kinetics was followed by measuring the fluorescence changes over time for AH(+) and A, which emit at different wavelengths. The studies at various pH values showed different mechanisms for the formation of the AH(+)@CB[7] complex, with this complex formed either by the binding of AH(+) or by the initial binding of A followed by protonation. In the latter case, it was possible to determine the protonation ((1.5 ± 0.4) × 10(9) M(-1) s(-1)) and deprotonation (89 ± 7 s(-1)) rate constants for complexed A/AH(+), which showed that the pKa shift of +3.1 for A/AH(+) in the complex is mainly due to a lower deprotonation rate constant.
authors.affiliation: Department of Chemistry, University of Victoria, PO Box 3065, Victoria, BC V8W 3V6, Canada. cornelia.bohne@gmail.com.
authors.forename: Suma S
authors.initials: SS
authors.lastname: Thomas
authors.affiliation: Department of Chemistry, University of Victoria, PO Box 3065, Victoria, BC V8W 3V6, Canada. cornelia.bohne@gmail.com.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Bohne
mesh_terms: D000588:Amines / Q000737:chemistry; D000873:Anthracenes / Q000737:chemistry*; D001952:Bridged-Ring Compounds / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000737:chemistry*; D007700:Kinetics; D015394:Molecular Structure; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
chemical_list: D000588:Amines; D000873:Anthracenes; D001952:Bridged-Ring Compounds; D002412:Cations; D007093:Imidazoles; C456276:cucurbit(7)uril; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils; C006593:2-anthramine