Meso-functionalized octamethoxyporphyrins: A new class of nonasubstituted porphyrins

Octamethoxyporphyrin containing multiple-donor substituents has been functionalized for the first time. A large number of its mono -meso-substituted derivatives with substit uents such as nitro, amino, N-methylamino, formyl, hydroxymethyl, oxime, cyano and carboxy functional groups have been synthesized and characterized. They form a new class of nonasubstitut ed porphyrins. Crystallographic studies on the cyano derivative show that the -CN group is in conjugation with the prophyrin π-system. The calculated optical transition energies and the electron densities on the imino nitrogens of the synth e- sised porphyrins using AMI calculations correlate well with the experimentally observed data. Meso - substituted porphyrins are found to be essentially planar.