New approaches will be developed for probing interfacial compositions of association colloids and vesicles over a wide range of surface charge densities and solution compositions. Product distributions from dediazoniation of an aggregate bound hydrophobic aryl diazonium salt will provide a "snapshot" view of interfacial nucleophile composition. This probe will be used to estimate, simultaneously, interfacial concentrations of water, and counterions, and also alcohol distributions and counterion selectivities. The effect of surface charge density on counterion binding and aggregate size and shape of micelles composed of amphoteric surfactants with phospholipid-like head groups will be determined by NMR, spectrophotometric, and potentiometric methods. %%% This grant from the Organic Dynamics Program supports the research of Professor Laurence S. Romsted at Rutgers University. Reactive species (aryl diazonium salts), bound to aggregated molecules (colloids and vesicles), will undergo reaction with solvent and other molecules at the aggregate-water interface to give a "snapshot" view of this interface. The effect of surface charge density on the aggregate and the shape of the aggregate will be determined by employing a variety of instrumental techniques. These studies will allow for a better understanding of an important biological process where the enzyme phospholipase A2 binds to phospholipid vesicles (aggregates).
