Synergistic "ping-pong" energy transfer for efficient light activation in a chromophore-catalyst dyad.
The synthesis of a porphyrin-Ru(II) polypyridine complex where the porphyrin acts as a photoactive unit and the Ru(II) polypyridine as a catalytic precursor is described. Comparatively, the free base porphyrin was found to outperform the ruthenium based chromophore in the yield of light induced electron transfer. Mechanistic insights indicate the occurrence of a ping-pong energy transfer from the (1)LC excited state of the porphyrin chromophore to the (3)MCLT state of the catalyst and back to the (3)LC excited state of the porphyrin unit. The latter, triplet-triplet energy transfer back to the chromophore, efficiently competes with fast radiationless deactivation of the excited state at the catalyst site. The energy thus recovered by the chromophore allows improved yield of formation of the oxidized form of the chromophore and concomitantly of the oxidation of the catalytic unit by intramolecular charge transfer. The presented results are among the rare examples where a porphyrin chromophore is successfully used to drive an oxidative activation process where reductive processes prevail in the literature.
Service de Bioénergétique, Biologie Structurale et Mécanismes (SB2SM), CEA, iBiTec-S, Biochimie Biophysique et Biologie Structurale (B3S), I2BC, UMR 9198, F-91191 Gif-sur-Yvette, France. annamaria.quaranta@cea.fr.
Annamaria
A
Quaranta
Georgios
G
Charalambidis
Christian
C
Herrero
Sofia
S
Margiola
Winfried
W
Leibl
Athanassios
A
Coutsolelos
Ally
A
Aukauloo
D002384:Catalysis; D004735:Energy Transfer; D008027:Light; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*
D009942:Organometallic Compounds; D011166:Porphyrins; D011725:Pyridines; D012428:Ruthenium