SYNTHESIS OF ULTRAFINE PARTICLES OF TRANSITION-METAL SULFIDES IN THE CAVITIES OF LIPID VESICLES AND THE LIGHT-STIMULATED TRANSMEMBRANE ELECTRON-TRANSFER CATALYZED BY THESE PARTICLES

A new method of synthesis of ultrafine (approximately 40 angstrom) transition metal sulphide particles (CdS and CuS) in the cavities of lipid vesicles has been developed. Sulphide precursor species are encapsulated in the vesicle cavities, and sulphide anions are added to the water phase outside the cavities (the outer solution). The rate V of formation of transition metal sulphide particles is regulated by adjusting the pH of the outer solution; in the initial stages this rate is proportional to the concentration of the molecular form of H2S in the outer solution: V = k[H2S] (k = 9 s-1). The growth of the particles can be stopped at any stage by adding an alkali to the outer solution. The rate and quantum yield of visible-light-stimulated transmembrane electron transfer in the lipid vesicles, containing CdS particles synthesized by this method in the cavities, and the electron carrier cetylviologen in the membrane, were studied.