“…In general, it has been reported that the addition of a donor on a radical improved the photostability of the radicals. 2 e,f ,3 b ,10,11,13 d ,15 Considering that the photostability of PyBTM was 71 times that of TTM in dichloromethane and 45 times that of TTM in cyclohexane, and that it was even comparable to closed-shell molecules with a long π-system such as TIPS pentacene, 7 a the improved photostability of 1 , 2 , and 3 showed excellent values.…”