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Improving the Efficiency of the Photoinduced Charge-Separation Process in a Rhenium(I)-Zinc Porphyrin Dyad by Simple Chemical Functionalization.
MedLine Citation:
PMID:  23461643     Owner:  NLM     Status:  Publisher    
We demonstrate here that, whereas the rhenium(I)-zinc porphyrin dyad fac-[Re(CO)3(bpy)(Zn·4'MPyP)](CF3SO3) [1; 4'MPyP = 5-(4'-pyridyl)-10,15,20-triphenylporphyrin] shows no evidence for photoinduced electron transfer upon excitation in the visible region because the charge-separated state ZnP+-Re- is almost isoenergetic with the singlet excited state of the zinc porphyrin (ΔG = -0.05 eV), the introduction of electron-withdrawing ethyl ester groups on the bpy ligand significantly improves the thermodynamics of the process (ΔG = -0.42 eV). As a consequence, in the new dyad fac-[Re(CO)3(4,4'-DEC-bpy)(Zn·4'MPyP)](CF3SO3) (4; 4,4'-DEC-bpy = 4,4'-diethoxycarbonyl-2,2'-bipyridine), an efficient and ultrafast intramolecular electron-transfer process occurs from the excited zinc porphyrin to the rhenium unit upon excitation with visible light. Conversely, the introduction of electron-donor tert-butyl groups on the meso-phenyl moieties of the zinc porphyrin has a negligible effect on the photophysics of the system. For dyad 4, the time constants for the charge-separation and charge-recombination processes in solvents of different polarity (PrCN, DCM, and toluene) were measured by an ultrafast time-resolved absorption technique (λexc = 560 nm).
Teresa Gatti; Paolo Cavigli; Ennio Zangrando; Elisabetta Iengo; Claudio Chiorboli; Maria Teresa Indelli
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-3-5
Journal Detail:
Title:  Inorganic chemistry     Volume:  -     ISSN:  1520-510X     ISO Abbreviation:  Inorg Chem     Publication Date:  2013 Mar 
Date Detail:
Created Date:  2013-3-6     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0366543     Medline TA:  Inorg Chem     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Department of Chemical and Pharmaceutical Sciences, University of Trieste , Via L. Giorgieri 1, 34127 Trieste, Italy.
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