Abstract
A molecular tetrad (C-P-QA-QB) consisting of a carotenoid polyene, a porphyrin and a diquinone moiety has been synthesized. The quinone with the lower reduction potential, the naphthoquinone (QA), was linked directly to the porphyrin and the benzoquinone (QB) was attached in series by a rigid bicyclic bridge. This arrangement was designed to promote a biomimetic sequential electron transfer from the porphyrin to QA, and on to QB. Cyclic voltammetric measurements show two distinct reduction steps at-0.65 and -0.46 V (vs. SCE) for the diquinone moiety, indicating independence of the benzoquinone and the naphthoquinone components. The initial charge separated state, C-P.+-QA.--Q-B is formed within 15 ps of excitation and lies about 1.6 eV above the ground state. The final charge separated state C.+-P-QA-QB.- is formed with a quantum yield of 0.23 at room temperature (0.5 at 240 K) and lies ca. 1.1 eV above the ground state. Both parallel and sequential mechanisms for the electron transfer processes are elucidated from studies with model triads which feature a carotenoid, a porphyrin and only one of the components of the diquinone moiety.
| Original language | English |
|---|---|
| Pages (from-to) | 4867-4891 |
| Number of pages | 25 |
| Journal | Tetrahedron |
| Volume | 45 |
| Issue number | 15 |
| DOIs | |
| Publication status | Published - 1989 |
Fingerprint
ASJC Scopus subject areas
- Biochemistry
- Organic Chemistry
- Drug Discovery
Cite this
A carotenoid-porphyrin-diquinone tetrad : synthesis, electrochemistry and photoinitiated electron transfer. / Gust, John Devens; Moore, Thomas A; Moore, Ana L; Seely, Gilbert; Liddell, Paul; Barrett, Donna; Harding, Larry O.; Ma, Xiaochun C.; Lee, Seung Joo; Gao, Feng.
In: Tetrahedron, Vol. 45, No. 15, 1989, p. 4867-4891.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A carotenoid-porphyrin-diquinone tetrad
T2 - synthesis, electrochemistry and photoinitiated electron transfer
AU - Gust, John Devens
AU - Moore, Thomas A
AU - Moore, Ana L
AU - Seely, Gilbert
AU - Liddell, Paul
AU - Barrett, Donna
AU - Harding, Larry O.
AU - Ma, Xiaochun C.
AU - Lee, Seung Joo
AU - Gao, Feng
PY - 1989
Y1 - 1989
N2 - A molecular tetrad (C-P-QA-QB) consisting of a carotenoid polyene, a porphyrin and a diquinone moiety has been synthesized. The quinone with the lower reduction potential, the naphthoquinone (QA), was linked directly to the porphyrin and the benzoquinone (QB) was attached in series by a rigid bicyclic bridge. This arrangement was designed to promote a biomimetic sequential electron transfer from the porphyrin to QA, and on to QB. Cyclic voltammetric measurements show two distinct reduction steps at-0.65 and -0.46 V (vs. SCE) for the diquinone moiety, indicating independence of the benzoquinone and the naphthoquinone components. The initial charge separated state, C-P.+-QA.--Q-B is formed within 15 ps of excitation and lies about 1.6 eV above the ground state. The final charge separated state C.+-P-QA-QB.- is formed with a quantum yield of 0.23 at room temperature (0.5 at 240 K) and lies ca. 1.1 eV above the ground state. Both parallel and sequential mechanisms for the electron transfer processes are elucidated from studies with model triads which feature a carotenoid, a porphyrin and only one of the components of the diquinone moiety.
AB - A molecular tetrad (C-P-QA-QB) consisting of a carotenoid polyene, a porphyrin and a diquinone moiety has been synthesized. The quinone with the lower reduction potential, the naphthoquinone (QA), was linked directly to the porphyrin and the benzoquinone (QB) was attached in series by a rigid bicyclic bridge. This arrangement was designed to promote a biomimetic sequential electron transfer from the porphyrin to QA, and on to QB. Cyclic voltammetric measurements show two distinct reduction steps at-0.65 and -0.46 V (vs. SCE) for the diquinone moiety, indicating independence of the benzoquinone and the naphthoquinone components. The initial charge separated state, C-P.+-QA.--Q-B is formed within 15 ps of excitation and lies about 1.6 eV above the ground state. The final charge separated state C.+-P-QA-QB.- is formed with a quantum yield of 0.23 at room temperature (0.5 at 240 K) and lies ca. 1.1 eV above the ground state. Both parallel and sequential mechanisms for the electron transfer processes are elucidated from studies with model triads which feature a carotenoid, a porphyrin and only one of the components of the diquinone moiety.
UR - http://www.scopus.com/inward/record.url?scp=0011433217&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0011433217&partnerID=8YFLogxK
U2 - 10.1016/S0040-4020(01)85157-7
DO - 10.1016/S0040-4020(01)85157-7
M3 - Article
AN - SCOPUS:0011433217
VL - 45
SP - 4867
EP - 4891
JO - Tetrahedron
JF - Tetrahedron
SN - 0040-4020
IS - 15
ER -