Continuous lifetime distributions of β-cyclodextrin-anilinonaphthalene sulfonic acid inclusion complexes.

Fluorescence lifetimes are reported for a series of anilinonaphthalene sulfonate (ANS) probe molecules complexed with β-cyclodextrin (β-CD). The fluorescence decay kinetics are recovered by multifrequency phase and modulation measurements in concert with a global analysis scheme. In all cases studied, a continuous Lorentzian distribution of lifetimes is observed, resulting from the dynamical nature of the ANS-β-CD complex and free ANS. Trends are discussed and comparisons made between bound and free fluorophore and between different isomeric ANS structures.