@Article{ChemPhysChem_8_1504, author = {C. Goze and C. Leiggener and S.-X. Liu and L. Sanguinet and E. Levillain and A. Hauser and S. Decurtins}, title = {{Fused Donor{\frac{ }{ }}Acceptor Ligands in Ru$^{II}$ Chemistry: Synthesis, Electrochemistry and Spectroscopy of [Ru(bpy)$_{3-n}$(TTF-dppz)$_{n}$](PF$_{6}$)$_{2}$}}, journal= {ChemPhysChem}, ISSN = {1439-4235}, volume= {8}, pages = {1504-1512}, url = {http://www3.interscience.wiley.com/cgi-bin/abstract/114269811/ABSTRACT}, eprint= {http://www.unige.ch/sciences/chifi/publis/refs_pdf/ref00890.pdf}, doi= {10.1002/cphc.200700066}, abstract = {{Three ruthenium(II) polypyridine complexes of general formula [Ru(bpy)$_{3-}${\em $_{n}$}(TTF-dppz){\em $_{n}$}](PF$_{6}$)$_{2}$ ({\em n}=1-3, bpy=2,2\'-bipyridine), with one, two or three redox-active TTF-dppz (4\',5\'-bis(propylthio)tetrathiafulvenyl[{\em i}]dipyrido[3,2-{\em a}:2\',3\'-{\em c}]phenazine) ligands, were synthesised and fully characterised. Their electrochemical and photophysical properties are reported together with those of the reference compounds [Ru(bpy)$_{3}$](PF$_{6}$)$_{2}$, [Ru(dppz)$_{3}$](PF$_{6}$)$_{2}$ and [Ru(bpy)$_{2}$(dppz)](PF$_{6}$)$_{2}$ and the free TTF-dppz ligand. All three complexes show intraligand charge-transfer (ILCT) fluorescence of the TTF-dppz ligand. Remarkably, the complex with {\em n}=1 exhibits luminescence from the Ru$^{2+}$dppz metal-to-ligand charge-transfer ($^{3}$MLCT) state, whereas for the other two complexes, a radiationless pathway via electron transfer from a second TTF-dppz ligand quenches the $^{3}$MLCT luminescence. The TTF fragments as electron donors thus induce a ligand-to-ligand charge-separated (LLCS) state of the form TTF-dppz$^{-}$-Ru$^{2+}$→ -dppz-TTF$^{+}$. The lifetime of this LLCS state is approximately 2.3 $\mu$s, which is four orders of magnitude longer than that of 0.4 ns for the ILCT state, because recombination of charges on two different ligands is substantially slower.}}, year = {2007} }