Reduction of dipyrido-[3,2-a:2,3-c]-phenazine (dppz) by photolysis in ethanol solution

Photolysis of dipyrido-[3,2-a:2ʹ,3ʹ-c]-phenazine (dppz)(1) in ethanol solution leads to the formation of 9,14-dihydrodipyridophenazine (2), which has been characterised by detailed NMR analysis, UV/VIS absorption spectroscopy, and theoretical calculations which reveal that its red colour is due to a low-lying intramolecular charge transfer state.