Spectral and kinetic identification of radical cations of pyrimidine bases by stepwise electron transfer

Radical cations of methylated derivatives of uracil and thymine were generated by electron transfer to the parent radical cation, generated in acetone by nanosecond pulse radiolysis. The resulting transient absorption peaking around 400 and 550 nm is assigned to the radical cations of the pyrimidine bases. Direct kinetic and spectroscopic evidence for this assignment has been given by a subsequent electron transfer from triphenylamine to the pyrimidine radical cations yielding the characteristic absorption spectrum of the triphenylamine radical cation.