Competition between Energy Transfer and Interligand Electron Transfer in Porphyrin−Osmium(II) Bis(2,2‘:6‘,2‘ ‘-terpyridine) Dyads

Autor:	Craig A. Sams, Andrew C. Benniston, Anthony Harriman, Consuelo Pariani
Rok vydání:	2007
Předmět:	chemistry.chemical_compound Electron transfer Intersystem crossing chemistry Excited state Intramolecular force Flash photolysis Physical and Theoretical Chemistry Terpyridine Triplet state Photochemistry Porphyrin
Zdroj:	The Journal of Physical Chemistry A. 111:8918-8924
ISSN:	1520-5215 1089-5639
Popis:	Rapid intramolecular energy transfer occurs from a free-base porphyrin to an attached osmium(II) bis(2,2':6',2' '-terpyridine) complex, most likely by way of the Förster dipole-dipole mechanism. The initially formed metal-to-ligand, charge-transfer (MLCT) excited-singlet state localized on the metal complex undergoes very fast intersystem crossing to form the corresponding triplet excited state ((3)MLCT). This latter species transfers excitation energy to the (3)pi,pi* triplet state associated with the porphyrin moiety, such that the overall effect is to catalyze intersystem crossing for the porphyrin. Interligand electron transfer (ILET) to the distal terpyridine ligand, for which there is no driving force, competes poorly with triplet energy transfer from the proximal (3)MLCT to the porphyrin. Equipping the distal ligand with an ethynylene residue provides the necessary driving force for ILET and this process now competes effectively with triplet energy transfer to the porphyrin. The rate constants for all the relevant processes have been derived from laser flash photolysis studies.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::6dbc39a1fe43e7e420751e6b7b174d41 https://doi.org/10.1021/jp0734326 Zobrazit plný text záznamu