Micellized sequestered silver atoms and small silver clusters

Abstract

Pulse radiolysis was used to examine the nature of the silver species obtained when an aqueous solution containing sequestered Ag{sup +} ions was reduced by hydrated electrons in the presence of a surfactant macrocyclic crown ether, labeled L, and/or a maltoside surfactant. The initially formed product is the Ag{sup 0}(L) species which rapidly loses its ligand (half-life {le}5 {mu}s) and reacts with another Ag{sup +}(L) ion to form Ag{sub 2}{sup +}(L). The latter species decays by a bimolecular process to form the Ag{sub 4}{sup 2+}(L){sub n} species at a faster rate than its ligand free analogue. Ultimately, colloidal metallic silver, (Ag){sub n}, forms which is stabilized by the surfactant moieties. No long-term stability to the reduced monomolecular species could be obtained.