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Shielding of Electron Acceptors Coordinated to Rhenium(I) by Carboxylato Groups. Intraligand and Charge‐Transfer Excited‐State Properties of fac ‐(‘Anthraquinone‐2‐carboxylato')(2,2′‐bipyridine)tricarbonylrhenium ( fac ‐[Re I (aq‐2‐CO 2 )(2,2′‐bipy)(CO) 3 ])
Author(s) -
Ruiz Gustavo T.,
Juliarena Maria P.,
Lezna Reynaldo O.,
Wolcan Ezequiel,
Feliz Mario R.,
Ferraudi Guillermo
Publication year - 2002
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(200205)85:5<1261::aid-hlca1261>3.0.co;2-d
Subject(s) - chemistry , photochemistry , excited state , bipyridine , carboxylate , electron transfer , moiety , anthraquinone , quenching (fluorescence) , rhenium , photoinduced electron transfer , ligand (biochemistry) , stereochemistry , crystallography , crystal structure , inorganic chemistry , organic chemistry , fluorescence , physics , quantum mechanics , biochemistry , receptor , nuclear physics
The photophysical and photochemical properties of ( OC ‐6‐33)‐(2,2′‐bipyridine‐ κN 1 , κN 1 ′)tricarbonyl(9,10‐dihydro‐9,10‐dioxoanthracene‐2‐carboxylato‐ κ O)rhenium ( fac ‐[Re I (aq‐2‐CO 2 )(2,2′‐bipy)(CO) 3 ]) were investigated and compared to those of the free ligand 9,10‐dihydro‐9,10‐dioxoanthracene‐2‐carboxylate (=anthraquinone‐2‐carboxylate) and other carboxylato complexes containing the (2,2′‐bipyridine)tricarbonylrhenium ([Re(2,2′‐bipy)(CO) 3 ]) moiety. Flash and steady‐state irradiations of the anthraquinone‐derived ligand ( λ exc 337 or 351 nm) and of its complex reveal that the photophysics of the latter is dominated by processes initiated in the Re‐to‐(2,2′‐bipyridine) charge‐transfer excited state and 2,2′‐bipyridine‐ and (anthraquinone‐2‐carboxylato)‐centered intraligand excited states. In the reductive quenching by N , N ‐diethylethanamine (TEA) or 2,2′,2″‐nitrilotris[ethanol] TEOA, the reactive states are the 2,2′‐bipyridine‐centered and/or the charge‐transfer excited states. The species with a reduced anthraquinone moiety is formed by the following intramolecular electron transfer, after the redox quenching of the excited state: [Re I (aq−2−CO 2 )(2,2′‐bipy . )(CO) 3 ] − ⇌[Re I (aq−2−CO 2 . )(2,2′‐bipy)(CO) 3 ] − The photophysics, particularly the absence of a Re I ‐to‐anthraquinone charge‐transfer excited state photochemistry, is discussed in terms of the electrochemical and photochemical results.