1. Excited-State Electron Transfer in a Chromophore−Quencher Complex. Spectroscopic Identification of a Redox-Separated State
- Author
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Ana María Leiva, Bárbara Loeb, Jon R. Schoonover, Rosa López, Martin Devenney, Kristin M. Omberg, Durwin R. Striplin, Thomas J. Meyer, Fernando Zuloaga, and Ester Norambuena
- Subjects
Inorganic Chemistry ,Electron transfer ,Crystallography ,Chemistry ,Ligand ,Excited state ,Ultrafast laser spectroscopy ,Physical and Theoretical Chemistry ,Chromophore ,Photochemistry ,Resonance (chemistry) ,Acceptor ,Quinone - Abstract
In the chromophore-quencher complex fac-[Re(Aqphen)(CO)(3)(py-PTZ)](+) (Aqphen is 12,17-dihydronaphtho[2,3-h]dipyrido[3,2-a:2',3'-c]-phenazine-12,17-dione; py-PTZ is 10-(4-picolyl)phenothiazine), Aqphen is a dppz derivative, containing a pendant quinone acceptor at the terminus of a rigid ligand framework. This introduces a third, low-lying, ligand-based pi acceptor level localized largely on the quinone fragment. Laser flash excitation of fac-[Re(Aqphen)(CO)(3)(py-PTZ)](+) (354.7 nm; in 1,2-dichloroethane) results in the appearance of a relatively long-lived transient that decays with tau(298K) = 300 ns (k = 3.3 x 10(6) s(-)(1)). Application of transient absorption, time-resolved resonance Raman, and time-resolved infrared spectroscopies proves that this transient is the redox-separated state fac-[Re(I)(Aqphen(*)(-)())(CO)(3)(py-PTZ(*)(+)())](+) in which the excited electron is localized largely on the quinone portion of the Aqphen ligand.
- Published
- 1999