Large magnetic field effect on back electron transfer from uncharged radical to its cationic partner in anionic micelle

Abstract

The magnetic field effect (MFE) on the radical pair (RP) generated by photoexcitation of the acetyl derivative of phenyl pyrylium ion (APP⁺) in the presence of biphenyl, an electron donor, has been investigated. The escape yield at 3.5 T is more than ten times the zero-field value. The MFE reaches near-saturation twice, once at fields of the order of 10mT and again at about 3.5 T. The low-field variation of the MFE conforms to the pattern expected for the isotropic HFC mechanism, and the high-field variation to that expected for the relaxation mechanism. In this particular system two types of radical pair are generated, one by electron transfer from the donor to the acceptor and another by H-abstraction from the micelle. The MFEs on the two types of ³RP have been compared.