This paper is part of a special issue dedicated to Professor J. C. (Tito) Scaiano on the occasion of his 60th birthday.
Photoreduction of Ru(bpy)3+2 by Amines in Aqueous Solution. Kinetics Characterization of a Long-Lived Nonemitting Excited State†
Article first published online: 30 APR 2007
Photochemistry and Photobiology
Volume 82, Issue 1, pages 213–218, January 2006
How to Cite
Rivarola, C. R., Bertolotti, S. G. and Previtali, C. M. (2006), Photoreduction of Ru(bpy)3+2 by Amines in Aqueous Solution. Kinetics Characterization of a Long-Lived Nonemitting Excited State. Photochemistry and Photobiology, 82: 213–218. doi: 10.1562/2005-05-31-RA-558
- Issue published online: 30 APR 2007
- Article first published online: 30 APR 2007
- Received 31 May 2005; accepted 8 August 2005; published online 12 August 2005
The photochemistry of Ru(bpy)3+2 in the presence of amines was investigated in water by laser flash photolysis. N,N′-Dimethylaniline and p-phenylenediamine quench the luminescent metal to ligand charge transfer (MLCT) excited state of the complex by an electron transfer reaction that produces the semireduced form Ru(bpy)3+ in relatively high yields. On the other hand, triethylamine (TEA) and aniline do not quench the MLCT. Nevertheless, when laser flash irradiation at 532 nm is carried out in the presence of these amines, the formation of Ru(bpy)3+ is clearly detected by its transient absorption at 510 nm. These results are interpreted by an electron transfer reaction with the participation of a non-emitting excited state of the complex, formed independently of the MLCT from the Franck-Condon or the relaxed singlet excited state. The rate constants for the quenching of this state by TEA and aniline and the quantum yields for Ru(bpy)3+ were determined. The new state is formed in a very fast process and has a lifetime of ca 4 μs in water.