Y. Takahashi et al., Highly efficient polypyridyl-ruthenium(II) photosensitizers with chelatingoxygen donor ligands: beta-diketonato-bis(dicarboxybipyridine)ruthenium, INORG CHIM, 310(2), 2000, pp. 169-174
A series of mono-cationic polypyridyl-ruthenium complexes with strongly ele
ctron donating beta -diketonate ligands {(dcbp)(2)Ru(L)}Cl, where dcbp = 4,
4'-dicarboxy-2,2'-bipyridine; L = acetylacetonate (1), 3-methyl-2,4-pentane
dionate (2), 1,3-diphenyl-1,3-propanedionate (3), have been synthesized as
molecular photosensitizers for a nanocrystalline TiO2 electrode. In alkalin
e methanol solution, these complexes exhibit intense visible light absorpti
on with low energy MLCT maxima above 517 nm which accompany a significantly
enhanced band tail, improving red light absorptivity beyond 600 nm. The ph
otoelectrochemical properties of these three diketonate complexes on a TiO2
semiconductor have been compared to cis-dithiocyanate complex, (dcbp)(2)Ru
(NCS)(2), which is one of the most efficient sensitizers reported to date.
The diketonate complexes show quite high performances in photoelectrochemic
al cells containing I-/I-3(-) electrolyte. The overall solar light-to-elect
rical energy conversion efficiencies are in the range of 6.0-3.9% while the
dithiocyanate complex yields 5.7% efficiency in our experiments. (C) 2000
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