EXTRAZEOLITE ELECTRON-TRANSFER AT ZEOLITE-ENCAPSULATED POLYPYRIDYL METAL-COMPLEX COATED ELECTRODES

Polypyridyl metal complexes ([Ru(bpy)(3)](2+) and [Fe(bpy)(3)](2+)) we re synthesized inside the supercages of zeolite-Y and adsorbed on the surface of zeolite-Y (represented as Ru(II)-Y-(c/s) and Fe(II)-Y-(c/s) , where ''c'' refers the supercage of zeolite-Y and ''s'' refers the s urface of zeolite-Y). These zeolite-encapsulated metal complexes were coated on a platinum electrode, and their electrochemical properties w ere studied in 0.1 M Na2SO4 and in 0.05 M H2SO4 The Ru(II)-Y-(c) and F e(II)-Y-(c) were electroinactive in 0.1 M Na2SO4. The same metal compl exes in zeolite show electrochemical activity in the presence of H+ io ns. The electroinactivity of Ru(II)-Y-(c) and Fe(II)-Y-(c) complexes i n 0.1 M Na2SO4 shows that the intrazeolite electron transfer is not oc curring. The disintegration of zeolite-Y in the presence of H+ ions le ads to the random distribution of the polypyridyl metal complexes and shows that extrazeolite electron-transfer mechanism is operating as in the case of zeolite surface adsorbed metal complexes.