Thus, DABNA-1 for this reaction acts as a pre-photocatalyst. We then studied the photodegradation of the PC and the formation of 1 and 2 as a function of time by 1 H NMR and absorption spectroscopy (Figure ). After 30 minutes, the intensity of the SRCT absorption band of DABNA-1 decreased in intensity to 84% of its original, while the dehalogenated product was detected only in trace amounts. The intensity of this band decreased steadily to 27% of its original intensity at 5 hours, while the yield of the dehalogenated product plateaued at 35%; however, after 24 h there is complete dehalogenation of methyl 4-chlorobenzoate.