TY - JOUR
T1 - Carotenoid triplet detection by time-resolved EPR spectroscopy in carotenopyropheophorbide dyads
AU - Carbonera, Donatella
AU - Di Valentin, Marilena
AU - Corvaja, Carlo
AU - Giacometti, Giovanni
AU - Agostini, Giancarlo
AU - Liddell, Paul A.
AU - Moore, Ana
AU - Moore, Thomas
AU - Gust, Devens
N1 - Funding Information:
This work was supported in part by MURST 40% national program ‘Liveproteins’ (grant to GG), and by US NSF (grant to DG and TAM).
PY - 1997/5/30
Y1 - 1997/5/30
N2 - Carotenoid triplets play a photoprotective role in natural photosynthesis. The main process of carotenoid triplet formation is known to be triplet-triplet energy transfer from chlorophyll triplets. The structural requirements for high transfer yields are still a matter of discussion and the presence of competitive triplet formation pathways has not been excluded. Transient EPR measurements of triplet states formed by photoexcitation allow detection of the initial spin polarization. This pattern derives from the mechanism of triplet formation. In the case of triplet-triplet energy transfer, if the condition of spin angular momentum conservation is fulfilled, simulation of the EPR spectra gives information about the donor-acceptor mutual orientation. We describe transient EPR experiments on two artificial photosynthetic dyads, consisting of a carotenoid covalently-linked to a free-base or zinc substituted pyropheophorbide moiety and we discuss the results in terms of possible dyad conformations.
AB - Carotenoid triplets play a photoprotective role in natural photosynthesis. The main process of carotenoid triplet formation is known to be triplet-triplet energy transfer from chlorophyll triplets. The structural requirements for high transfer yields are still a matter of discussion and the presence of competitive triplet formation pathways has not been excluded. Transient EPR measurements of triplet states formed by photoexcitation allow detection of the initial spin polarization. This pattern derives from the mechanism of triplet formation. In the case of triplet-triplet energy transfer, if the condition of spin angular momentum conservation is fulfilled, simulation of the EPR spectra gives information about the donor-acceptor mutual orientation. We describe transient EPR experiments on two artificial photosynthetic dyads, consisting of a carotenoid covalently-linked to a free-base or zinc substituted pyropheophorbide moiety and we discuss the results in terms of possible dyad conformations.
KW - Carotenoids
KW - Dyads
KW - Porphyrins
KW - TREPR
KW - Triplets
UR - http://www.scopus.com/inward/record.url?scp=0031591344&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0031591344&partnerID=8YFLogxK
U2 - 10.1016/S1010-6030(96)04571-6
DO - 10.1016/S1010-6030(96)04571-6
M3 - Article
AN - SCOPUS:0031591344
SN - 1010-6030
VL - 105
SP - 329
EP - 335
JO - Journal of Photochemistry and Photobiology A: Chemistry
JF - Journal of Photochemistry and Photobiology A: Chemistry
IS - 2-3
ER -