Nitrooctaethylporphyrins: Synthesis, Optical and Redox Properties
Gong, L. and David Dolphin
Can. J. Chem.
The reaction of Zn octaethylporphyrin with N2O4 in CH2Cl2 gives, in a stepwise reaction, the Zn complexes of mono-, di-, tri-, and tetra-nitrooctaethylporphyrins. Demetalation, under acidic conditions, gives the corresponding free base porphyrins. The meso-nitro groups exert both steric and electronic effects on the porphyrin macrocycle. Thus N-protonation of the nitrated species causes a distortion of the ring and gives an optical spectrum similar to that of protonated meso-aryl-substituted porphyrins. In addition, the nitro groups make the oxidation of the porphyrin ring more difficult and at the same time facilitate the ring reductions.