Role of excited singlet state in the photooxidation of carotenoids: A time-resolved Q-band EPR study

被引:20
作者
Jeevarajan, AS
Kispert, LD
Avdievich, NI
Forbes, MDE
机构
[1] UNIV ALABAMA, DEPT CHEM, TUSCALOOSA, AL 35487 USA
[2] UNIV N CAROLINA, DEPT CHEM, VENABLE & KENAN LABS, CHAPEL HILL, NC 27599 USA
关键词
D O I
10.1021/jp952180i
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Spin-polarized 35 GHz time-resolved EPR (TREPR) spectra were obtained for the first time of the cation radicals of beta-carotene (I), 15,15'-didehydro-beta-carotene (II), 7',7'-dicyano-7'-apo-beta-carotene (III), and 7'-cyano-7'-ethoxycarbonyl-7'-apo-beta-carotene (IV) and the anion radical of the solvent which were formed by 308 nm photoexcitation of the carotenoids in carbon tetrachloride solution. Although the EPR spectra are weak in intensity due to the small dimensions of the 35 GHz quartz flat cell and have very broad line widths, it was possible to positively determine from the polarization pattern that the electron transfer to the solvent occurs from the excited singlet state of the carotenoids, The 35 GHz EPR spectra consist of two resolved EPR lines (one absorption and one emission) from which it has been possible to measure the g factor and Delta H-pp of the solvent-separated radical ion pair that was formed; measurements were not possible at 9 GHz.
引用
收藏
页码:669 / 671
页数:3
相关论文
共 25 条
[1]   THEORETICAL ASPECTS OF CHEMICALLY-INDUCED MAGNETIC-POLARIZATION [J].
ADRIAN, FJ .
RESEARCH ON CHEMICAL INTERMEDIATES, 1991, 16 (02) :99-125
[2]   TIME-RESOLVED EPR-SPECTRA OF SHORT BIRADICALS (1,3 TO 1,8) IN SOLUTION - THE INTERCONNECTING ROLES OF THE EXTERNAL MAGNETIC-FIELD, DIPOLAR COUPLING, EXCHANGE INTERACTION, AND MOLECULAR-MOTION IN THE SPIN POLARIZATION AND RELAXATION MECHANISMS [J].
FORBES, MDE ;
RUBERU, SR .
JOURNAL OF PHYSICAL CHEMISTRY, 1993, 97 (50) :13223-13233
[3]   A FAST 35-GHZ TIME-RESOLVED EPR APPARATUS [J].
FORBES, MDE .
REVIEW OF SCIENTIFIC INSTRUMENTS, 1993, 64 (02) :397-402
[4]   CAROTENOIDS IN PHOTOSYNTHESIS - STRUCTURE AND PHOTOCHEMISTRY [J].
FRANK, HA ;
VIOLETTE, CA ;
TRAUTMAN, JK ;
SHREVE, AP ;
OWENS, TG ;
ALBRECHT, AC .
PURE AND APPLIED CHEMISTRY, 1991, 63 (01) :109-114
[5]  
HAND E, UNPUB
[6]   SYNTHESIS AND NMR-SPECTROSCOPIC STRUCTURE DETERMINATION OF NOVEL 7,7'-DIPHENYL-7,7'-DIAPOCAROTENOIDS [J].
HAND, ES ;
BELMORE, KA ;
KISPERT, LD .
HELVETICA CHIMICA ACTA, 1993, 76 (05) :1939-1948
[7]   S1 AND T1 SPECIES OF BETA-CAROTENE GENERATED BY DIRECT PHOTOEXCITATION FROM THE ALL-TRANS, 9-CIS, 13-CIS, AND 15-CIS ISOMERS AS REVEALED BY PICOSECOND TRANSIENT ABSORPTION AND TRANSIENT RAMAN SPECTROSCOPIES [J].
HASHIMOTO, H ;
KOYAMA, Y ;
HIRATA, Y ;
MATAGA, N .
JOURNAL OF PHYSICAL CHEMISTRY, 1991, 95 (08) :3072-3076
[8]   ELECTRON SPIN RESONANCE SPECTRUM OF TRICHLOROMETHYL RADICAL IN SOLUTION [J].
HUDSON, A ;
HUSSAIN, HA .
MOLECULAR PHYSICS, 1969, 16 (02) :199-&
[9]   ESR STUDIES OF EAQ- IN LIQUID SOLUTION USING PHOTOLYTIC PRODUCTION [J].
JEEVARAJAN, AS ;
FESSENDEN, RW .
JOURNAL OF PHYSICAL CHEMISTRY, 1989, 93 (09) :3511-3514
[10]   AN ENDOR STUDY OF CAROTENOID CATION RADICALS ON SILICA-ALUMINA SOLID SUPPORTS [J].
JEEVARAJAN, AS ;
KISPERT, LD ;
PIEKARASADY, L .
CHEMICAL PHYSICS LETTERS, 1993, 209 (03) :269-274