DIPOLE ORIENTED ANION BINDING AND EXCHANGE IN ZWITTERIONIC MICELLES

The binding of 8-hydroxy-1,3,6-pyrenetrisulfonate anion (POH) to zwitterionic interfaces of 3-(N-hexadecyl-N,N-dimethylammonium)propanesulfonate (HPS), lysolecithin (lysPC) micelles, or lecithin sonicated vesicles was measured by steady-state fluorescence emission of POH. The addition of inert salts displaced bound POH in the three systems, showing the electrostatic nature of the binding. H-1 NMR spectra, degree of polarization of fluorescence (P), and emission intensities due to the excited-state prototropic dissociation of POH together pointed to a dipole-potential-driven anion binding and exchange in these formally neutral surfaces.