KINETIC INVESTIGATIONS OF NEW VIOLOGEN DERIVATIVES FOR WATER PHOTOLYSIS - THE 1ST RELAY COMPOUND WITH STABLE RADICALS

Six new electron relay compounds for the transfer of electrons from excited dyes [e.g.tris(2,2'-bipyridyl)ruthenium(II) chloride, Ru(bipy)3(2+*)] to catalysts (e.g. colloidal Pt) in aqueous photolytical systems were studied. The discharging rate constants of the radicals on different platinum catalysts were measured. The hydrogen production rates and quantum yields of systems with Ru(bipy)3(2+), electron relay, EDTA and Pt were determined. The stability of 1,1'',1'''-trimethyl[4,2';4',4'';6',4''']quaterpyridinium trichloride, against oxygen, was much higher than that of methyl viologen and its derivatives. With this relay compound hydrogen production was achieved even in the presence of dissolved oxygen. The quantum yields (400 < lambda < 500 nm) were between 1 and 26%. The absorption coefficients of the electron relay radicals were measured.