INCLUSION AND FLUORESCENCE QUENCHING OF 2,3-DIMETHYLNAPHTHALENE IN BETA-CYCLODEXTRIN CAVITIES

The fluorescence quenching of 2,3-dimethylnaphthalene (DMN) incorporat ed to beta-cyclodextrin (beta-CD) cavities by different olefins (fumar onitrile, acrylonitrile, acrylamide and 2-hydroxyethylmethacrylate) ha s been measured as a function of the beta-CD concentration. The quench ing efficiency decreases when the beta-CD concentration increases, but extrapolation of the data to infinite cavities concentration does not indicate complete protection. These results are interpreted in terms of two quenching processes, one of them taking place between 2,3-dimet hylnaphthalene associated to a beta-CD cavity and free quencher, and t he other between the DMN and the quencher molecule, both associated wi th a different cavity. The rate constants of both quenching processes and the beta-CD quencher association constant are obtained from the de pendence of the quenching efficiency with beta-CD concentration.