Fusion-Fission Transport of Probes and Quenchers in Microdomains of an Amphiphilic Ionene Polyelectrolyte†

Abstract

In aqueous solution, amphiphilic ionenes such as the [3,22]-ionene spontaneously adopt globular conformations and form microdomains that are highly micelle-like, i.e. are capable of solubilizing organic molecules, binding and exchanging counterions and accelerating or inhibiting the rates of bimolecular reactions. Time-resolved fluorescence decay of pyrene and pyrene derivatives solubilized in these microdomains at concentrations where excimer formation occurs show that even water-insoluble probes can migrate between the hydrophobic microdomains formed in aqueous solution by a [3,22]-ionene chloride (with the N-terminal groups quaternized with benzyl chloride). Time-resolved studies of the quenching of pyrene fluorescence by alkylpyridine derivatives revealed similar behavior. The observed quenching behavior requires that the migration be between microdomains on the same ionene chain or same group of associated ionene chains and is consistent with migration dominated by fusion/fission transport of the probe and quencher.