Modulation of Guest Partitioning Within Dendrimer–Surfactant Supramolecular Assemblies

Abstract

ABSTRACT Electrostatic interactions are used to create a template-assisted supramolecular assembly consisting of a polymeric dendrimer at the core and amphiphilic substrates on the periphery. The dendrimer generation and the chemical structure of the amphiphiles are varied to construct multiple and distinct microenvironments within the dendrimer–ligand complex for encapsulation of small guest molecules. In particular, these investigations employ a guest molecule that is a neutral fluorescent probe that exhibits an emission wavelength with an extreme sensitivity to the polarity of its surroundings. Partitioning of the fluorophore within the various microregions of the dendrimer–surfactant supramolecular complex is distinguished by the characteristic emission wavelengths of the overlapping Gaussian functions comprising the overall fluorescence spectrum. The observed variations in the prodan emission spectrum suggest interaction of prodan at protonated amino groups (460-nm emission), within dendritic branches and surfactant tails (490-nm emission), and in interior regions of the dendrimer core (430-nm emission). We demonstrate that the positioning of the guest molecule within the supramolecular complex can be modulated through the selection of dendrimer generation, surfactant chain length, and dendrimer:surfactant concentration ratio.