ORGN 766 |
| A new and efficient electron injection and electron trapping system was designed and synthesized for the studies of the kinetics of excess electron transfer (EET) through DNA. Photolysis of α-hydroxy phenyl ketones by 355 nm laser under neutral or basic conditions gave ketyl radicals and ketyl radical anions respectively, which were used as the single-electron injectors to reduce the DNA bases. For detection, 5- and 6-diphenylcyclopropyl uracils were synthesized to trap their radical anions upon reduction by fast ring opening to give diphenylalkyl radical that absorbs stongly at 335 nm. Our experiments showed that only 6-diphenylcyclopropyl uracil can trap its radical anion. Kinetics was monitored at 335 nm for the intramolecular EET from ketyl radical anion to uracil, which gave k = 1.4×10^6 s^(-1) over a calculated distance about 9.5 Å. This rate constant was compared with intramolecular EET to other electron acceptors, such as 9-fluorenone and alkyl ketone.
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Physical Organic Chemistry: Calculations, Mechanisms, Photochemistry, and High Energy Species
8:00 AM-12:00 PM, Thursday, March 29, 2007 McCormick Place Lakeside -- Room E451A/B, Level 4, Oral
Division of Organic Chemistry |
