Abstract
Phylloquinone biradical triplet species were generated by 300 nm irradiation of frozen (77 K) solutions or by treatment with AlCl3. The shape of the (Δms=1) electron paramagnetic resonance (EPR) signal of the triplet is axially symmetric (E=0) with D=19±0.5 mT for photo-induced and D=11.2±0.5 mT for chemically induced radicals. A half-field signal (Δms=2) in the region of g≈4 was detected in both cases, confirming its assignment as a triplet. An additional line arising at the center of the (Δms=1) signal with g=2.0048±0.0002 was assigned to the phylloquinone radical anion (PhQ•-). Electron nuclear double resonance (ENDOR) measurements of the triplet revealed the sign of the D parameter. For photo-generated radicals it appeared to be negative, which is the characteristic of radical dimers with well-separated partners (biradicals). Spin-spin distances of 5.3 and 6.3 Å, respectively, were estimated from the D parameter of photo-generated and chemically prepared phylloquinone biradicals.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 255-260 |
| Number of pages | 6 |
| Journal | Journal of Photochemistry and Photobiology A: Chemistry |
| Volume | 161 |
| Issue number | 2-3 |
| DOIs | |
| State | Published - Jan 30 2004 |
| Externally published | Yes |
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Keywords
- Biradicals
- Electron nuclear double resonance
- Electron paramagnetic resonance
- Electron transfer
- Phylloquinone
ASJC Scopus subject areas
- Bioengineering
- Physical and Theoretical Chemistry
Cite this
Photo- and chemically-produced phylloquinone biradicals : EPR and ENDOR study. / Konovalova, Tatyana A.; Kispert, Lowell D.; Redding, Kevin.
In: Journal of Photochemistry and Photobiology A: Chemistry, Vol. 161, No. 2-3, 30.01.2004, p. 255-260.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Photo- and chemically-produced phylloquinone biradicals
T2 - EPR and ENDOR study
AU - Konovalova, Tatyana A.
AU - Kispert, Lowell D.
AU - Redding, Kevin
PY - 2004/1/30
Y1 - 2004/1/30
N2 - Phylloquinone biradical triplet species were generated by 300 nm irradiation of frozen (77 K) solutions or by treatment with AlCl3. The shape of the (Δms=1) electron paramagnetic resonance (EPR) signal of the triplet is axially symmetric (E=0) with D=19±0.5 mT for photo-induced and D=11.2±0.5 mT for chemically induced radicals. A half-field signal (Δms=2) in the region of g≈4 was detected in both cases, confirming its assignment as a triplet. An additional line arising at the center of the (Δms=1) signal with g=2.0048±0.0002 was assigned to the phylloquinone radical anion (PhQ•-). Electron nuclear double resonance (ENDOR) measurements of the triplet revealed the sign of the D parameter. For photo-generated radicals it appeared to be negative, which is the characteristic of radical dimers with well-separated partners (biradicals). Spin-spin distances of 5.3 and 6.3 Å, respectively, were estimated from the D parameter of photo-generated and chemically prepared phylloquinone biradicals.
AB - Phylloquinone biradical triplet species were generated by 300 nm irradiation of frozen (77 K) solutions or by treatment with AlCl3. The shape of the (Δms=1) electron paramagnetic resonance (EPR) signal of the triplet is axially symmetric (E=0) with D=19±0.5 mT for photo-induced and D=11.2±0.5 mT for chemically induced radicals. A half-field signal (Δms=2) in the region of g≈4 was detected in both cases, confirming its assignment as a triplet. An additional line arising at the center of the (Δms=1) signal with g=2.0048±0.0002 was assigned to the phylloquinone radical anion (PhQ•-). Electron nuclear double resonance (ENDOR) measurements of the triplet revealed the sign of the D parameter. For photo-generated radicals it appeared to be negative, which is the characteristic of radical dimers with well-separated partners (biradicals). Spin-spin distances of 5.3 and 6.3 Å, respectively, were estimated from the D parameter of photo-generated and chemically prepared phylloquinone biradicals.
KW - Biradicals
KW - Electron nuclear double resonance
KW - Electron paramagnetic resonance
KW - Electron transfer
KW - Phylloquinone
UR - http://www.scopus.com/inward/record.url?scp=0347026683&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0347026683&partnerID=8YFLogxK
U2 - 10.1016/j.nainr.2003.08.003
DO - 10.1016/j.nainr.2003.08.003
M3 - Article
VL - 161
SP - 255
EP - 260
JO - Journal of Photochemistry and Photobiology A: Chemistry
JF - Journal of Photochemistry and Photobiology A: Chemistry
SN - 1010-6030
IS - 2-3
ER -