蒽醌/氢给体/氮氧自由基的瞬态电子自旋极化

Transient Electron Polarization of Anthraquinone/Hydrogen-donor/2,2,6,6-tetramethyl-piperidinyloxyl

用时间分辨电子自旋共振波谱仪研究了光解蒽醌/乙二醇、蒽醌/乙二醇/氮氧自由基体系的化学诱导动态电子自旋极化.实验结果指出,在蒽醌/乙二醇/氮氧自由基(AQ/EG/TEMPO)体系中,存在自由基三重态对(RTPM)和三重态(TM)极化的竞争,并由此讨论了三重态-自由基对的反应速率.

The chemically induced dynamic elec tron polarization(CIDEP)of the antheraquinone(AQ)/ethy-lene glycol (EG)and AQ /EG /2,2,6,6-tetramethyl-pi peridinyloxyl (TEMPO)systems were investigated using time-resolved ESR spectrometer.In AQ /EG system,the electron spin pola rized signal of antheraquinone radi cal is generated due to hydrogen abstrac tion from EG(Fig.1),this is a triplet mechanism(TM)accompanied by radical pair mechanism(RPM).On the an addition of TEMPO to the system,the chemically induced dynamic electron polarization signal of TEM PO is also evident,this is a radical-triplet pair mechanism(RTPM),so in the AQ /EG /TEMPO system,there are competition between RTPM and TM or RPM pola rization,along with the change of the concentration of TEMPO in the solution,the signal intensit ies of antheraquinone radical and TEMPO are changed(Fig.2and Fig.3),from this competition,the reactio n rate of the radical-triplet pair has been deduced(Table 1).