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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 6, Number 5
May 20, 1985 

Novel Effects of Polyelectrolytes on Fluorescence Quenching of Tris(2,2'-bipyridine)ruthenium(Ⅱ) by Methyl Viologen and Cu2+
Joon Woo Park, Young Hee Paik
The addition of poly(styrenesulfonate) (PSS) to Ru(bpy)32+ solutions shifted the emission peak by 3 nm to red, and increased emission intensity by 1.8 times. By contrast, poly(vinylsulfonate) (PVS) had little effect on the fluorescence spectrum. The effects of PSS on the spectral properties of Ru(bpy)32+, were attributed to the presence of a hydrophobic phenyl group in PSS, which interact with Ru(bpy)32+ by, at least in part, hydrophobic effect. The binding constant of Ru(bpy)32+ to PSS in 0.1 M NaCl was 6×104 M-1, and this value was about 103 times higher than those of methyl viologen (MV2+) and Cu2+. The Stern-Volmer constants of emission quenching of Ru(bpy)32+ by MV2+ and Cu2+ in 0.1 M NaCl solutions were 426 and 40 M-1, which correspond to second order rate constants(kq) of 1.1×109 and 1.0×108 M-1s-1, respectively. The presence of PSS enhanced KSV's by ∼50 times, whereas PVS increased the values only 1-4 times. The large enhancing effect of PSS, despite of lower charge density than PVS, was explained in terms of longer life-time of photoexcited Ru(bpy)32+ bound to PSS and strong association of Ru(bpy)32+ to PSS due to a specific interaction involving hydrophobic effect. The variation of KSV's on the concentrations of PVS and PSS were also investigated for Ru(bpy)32+-MV2+ and Ru(bpy)32+-Cu2+ photoredox systems.
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