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Fused Donor–Acceptor Ligands in Ru II Chemistry: Synthesis, Electrochemistry and Spectroscopy of [Ru(bpy) 3− n (TTF‐dppz) n ](PF 6 ) 2
Author(s) -
Goze Christine,
Leiggener Claudia,
Liu ShiXia,
Sanguinet Lionel,
Levillain Eric,
Hauser Andreas,
Decurtins Silvio
Publication year - 2007
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200700066
Subject(s) - chemistry , ruthenium , phenazine , luminescence , ligand (biochemistry) , photochemistry , bipyridine , acceptor , crystallography , electrochemistry , electron transfer , redox , inorganic chemistry , crystal structure , materials science , catalysis , organic chemistry , electrode , biochemistry , condensed matter physics , receptor , physics , optoelectronics
Three ruthenium(II) polypyridine complexes of general formula [Ru(bpy) 3− n (TTF‐dppz) n ](PF 6 ) 2 ( n =1‐3, bpy=2,2′‐bipyridine), with one, two or three redox‐active TTF‐dppz (4′,5′‐bis(propylthio)tetrathiafulvenyl[ i ]dipyrido[3,2‐ a :2′,3′‐ 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 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 μs, 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.