LUMINESCENCE BEHAVIOR OF TRIS(2,2'-BIPYRIDINE)RUTHENIUM(II) AND BIS(2,2'-BIPYRIDINE-4,4'-DISULFONATE)RUTHENATE(II) WITH COBALT(III)-COMPLEX-CONTAINING POLY(METHACRYLIC ACID)

Luminescence behavior of Ru(bpy)(3)(2+) (bpy = 2,2'-bipyridine) and Ru (bpy)(bpds)(2)(2-) (bpds = 2,2'-bipyridine-4,4'-disulfonate dianion) i n aqueous solution of cobalt(III)-complex-containing poly(methacrylic acid) (Co(III)PMA), which is affected by a unique pH-induced conformat ional transition, was investigated by means of fluorescence spectrosco py. The bell-shaped pH dependence of the luminescence intensity of the photoexcited Ru(bpy)(3)(2+) with a maximum value at pH 5 was observed for Ru(bpy)(3)(2+) in Co(III)PMA solutions. The maximum wavelength of the luminescence (lambda(max)) also depended on pH and the blue shift was observed at pH 5. The luminescence behavior of the photoexcited R u(bpy)(bpds)(2)(2-) was independent of pH in Co(III)PMA solutions. The Ru(bpy)(3)(2+) species were strongly interacted with CoPMA at pH 5, w hile the Ru(bpy)(bpds)(2)(2-) species had no interaction. Stern-Volmer plots for the quenching of Ru(bpy)(bpds)(2)(2-) with Co(III)PMA gave straight lines at various pH, The fact also indicated that the Ru(bpy) (bpds)(2)(2-) species have no interaction with Co(III)PMA at any pH. T he observed quenching constants significantly depended on pH and sharp ly decreased in the pH range of 3.5 to 5, It was suggested that the qu enching reaction was influenced by the pH-induced conformational trans ition of Co(III)PMA.