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.