Control of the size and photochemical properties of Q-CdS particles attached to the inner and/or outer surface of the lecithin vesicle bilayer membrane by the nature of its precursors

Cadmium sulfide nanoparticles have been generated in situ on the inner and/ or outer surfaces of monolamellar lecithin vesicles. Chemical agents, stron gly chelating or bounding the Cd2+ cations, are shown to influence dramatic ally the size of CdS nanoparticles as well as their optical, luminescence a nd photochemical properties. The more stable is a Cd2+-containing complex c reated by these chelating agents, the smaller are the CdS particles formed In case of CdCl2 and Cd(NO3)(2) as the CdS precursors inside the vesicles, a steady rise in the size of growing CdS nanoparticles is observed, while i n case of K-2[CdEDTA] the accumulation of mass of growing CdS occurs withou t a change in the nanoparticles size. The size of CdS particles and their i nitial growth rate depend also on pH of the vesicle suspension, modificatio n of the lipid membrane, being, however, independent of the CdCl2 concentra tion, if CdCl2 is the CdS precursor. In the presence of a sacrificial elect ron donor (S2- or EDTA), the bandgap irradiation of the lipid-vesicle-suppo rted CdS particles yields charge separation and electron transfer to lipoph ilic cetylviologen bications, C16V2+, embedded into the lipid bilayer. The initial quantum yield of C16V.+ formation depends on the topology of vesicu lar systems and CdS localization on the inner or outer surface of the lecit hin membrane. Presence of EDTA anions enhances sufficiently the initial qua ntum yield of vectorial electron phototransfer from CdS nanoparticles to ce tylviologen. (C) 1999 Elsevier Science S.A. All rights reserved.