Genre
- Journal Article
The rate constants (k) for reactions between a series of excited singlet state donors and the antimalarial agent, Artemisinin (ART), were measured in acetonitrile using fluorescence quenching techniques. A plot of log(k) correlates with the excited state oxidation potential of the donor, E-D(/D*).+, while a similar plot of log(k) versus the singlet energy of the donor, E-s, which if linear would indicate an energy transfer reaction process, shows a poor correlation. The results suggest that the determined rate constants are for dissociative electron transfer (ET) from the excited slate donor to the O-O bond in ART. Using our recently determined standard dissociative reduction potential for ART, E-diss(0), the rate constants are related to the free energy of ET, DeltaG(ET)(0). Analysis of the kinetic data as a function of DeltaG(ET)(0) correlates well with theories of ET modified for the non-adiabatic nature of the ET to peroxides. A number of thermochemical parameters are estimated from the analysis, in particular the intrinsic barrier (DeltaG(0)(not equal)) that is comprised of the solvent reorganization energy (lambda) and the bond dissociation enthalpy of the O-O bond. (C) 2001 Elsevier Science B.V. All rights reserved.
Univ Western Ontario, Dept Chem, London, ON N6A 5B7, Canada.; Workentin, MS, Univ Western Ontario, Dept Chem, London, ON N6A 5B7, Canada.
LAUSANNE; PO BOX 564, 1001 LAUSANNE, SWITZERLAND
ELSEVIER SCIENCE SA
PT: J; CR: ANDRIEUX CP, 1998, J AM CHEM SOC, V120, P4167 ANTONELLO S, 1997, J AM CHEM SOC, V119, P12595 ANTONELLO S, 1997, J AM CHEM SOC, V119, P9541 ANTONELLO S, 1999, J AM CHEM SOC, V121, P9668 BHISUTTHIBHAN J, 1998, J BIOL CHEM, V273, P16192 CHAN KL, 1997, PHYTOCHEMISTRY, V46, P1209 COSTENTIN C, 2000, J PHYS CHEM A, V104, P7492 DONKERS RL, UNPUB EUR J CHEM DONKERS RL, 1998, J PHYS CHEM B, V102, P4061 DONKERS RL, 1999, J AM CHEM SOC, V121, P7239 ENCINAS MV, 1982, J PHOTOCHEM, V20, P153 ENGEL PS, 1983, J PHYS CHEM-US, V87, P10 HAYNES RK, 1997, ACCOUNTS CHEM RES, V30, P73 INGOLD KU, 1984, CHEM PHYS LETT, V110, P433 ISSE AA, 1999, ACTA CHEM SCAND, V53, P1013 JIANG HL, 1997, INDIAN J CHEM B, V36, P154 KLAYMAN DL, 1985, SCIENCE, V228, P1049 KOJIMA H, 1975, J AM CHEM SOC, V97, P6317 MESHNICK SR, 1996, MICROBIOL REV, V60, P301 POSNER GH, 1998, J MED CHEM, V41, P940 POSNER GH, 1999, J MED CHEM, V42, P300 ROBERT A, 1998, CHEM SOC REV, V27, P273 ROBERT M, 2000, J AM CHEM SOC, V122, P514 SAVEANT JM, 1987, J AM CHEM SOC, V109, P6788 SAVEANT JM, 1990, ADV PHYS ORG CHEM, V26, P1 SAVEANT JM, 1992, J AM CHEM SOC, V114, P10595 SAVEANT JM, 1994, ADV ELECT T, V4, P53 SCAIANO JC, 1981, J AM CHEM SOC, V103, P640 STEWART LC, 1983, J AM CHEM SOC, V105, P3605 URANO T, 1984, J PHOTOCHEM, V26, P69 WAGNER PJ, 1989, HDB ORGANIC PHOTOCHE, V2, P251 WORKENTIN MS, 1998, J AM CHEM SOC, V120, P2664 WU WM, 1998, J AM CHEM SOC, V120, P3316 WU YK, 1999, ANGEW CHEM INT EDIT, V38, P2580 ZHANG F, 1992, BIOCHEM PHARMACOL, V43, P1805; NR: 35; TC: 10; J9: J PHOTOCHEM PHOTOBIOL A-CHEM; PG: 6; GA: 383HH
Source type: Electronic(1)
Language
- English
Subjects
- TRIOXANES
- ARTEMISININ
- DRUG ARTEMISININ
- ALKYL-HALIDES
- endoperoxides
- DYNAMICS
- Chemistry, Physical
- radical anion
- MECHANISM
- QINGHAOSU ARTEMISININ
- dissociative electron transfer
- ELECTROREDUCTION
- photoinduced electron transfer
- SOLVENTS
- DIALKYL PEROXIDES