Photochemistry of 4-(2-Nitrophenyl)-1,4-dihydropyridines. Evidence for Electron Transfer and Formation of an Intermediate

New evidence about the path followed in the photochemical reaction of 4-(2-nitrophenyl)-1,4-dihydropyridines such as the drugs nifedipine and nisoldipine to give the corresponding nitrosophenylpyridines has been found through determination of the steady-state photochemical parameters and a comparison of the photoreactions in solution and in matrix at 90 K. Additional support is given by comparison with the isomeric 4-(3-nitrophenyl)dihydropyridine as well as with simpler derivatives, such as the corresponding 4-methyldihydropyridine.