Abstract
Highly conjugated porphyrins have attracted attention as conducting materials, near IR dyes, nonlinear optical materials, or photosensitizers for photodynamic therapy of cancer tissues on in vivo studies. In addition, highly conjugated porphyrins and their metal complexes are very difficult to purify, since they are insoluble in most organic solvents. We have reported a simple solution of these problems using 4,7-dihydro-4,7-ethano-2H-isoindole as a synthon of isoindole for benzoporphyrin synthesis. Thus, heating porphyrins fused with bicyclo[2.2.2]octadiene rings at 160-170 °C results in clean formation of benzoporphyrins via retro Diels-Alder reaction and the products are pure and do not require further purification. And we succeeded synthesis of porphyrin dimer. This method is using bipyrrole and tripyrrane dicarbaldehyde for porphyrin dimer fused with bicyclo[2.2.2]octadiene by the 3+1 approach. Then we prepared a conjugated porphyrin dimer from a non-conjugated porphyrin dimer via retro Diels-Alder reaction. And we prepared the compound where rings of porphyrin and pyrrole fused with a bicyclo[2.2.2]octadinene skeleton, which could be converted to a benzene ring by the thermal retro-Diels-Alder reaction. Starting from known 4,8-dihydro-4, 8-ethanobenzo dipyrrole, the aimed porphyrin was prepared. Then we prepared porphyrin oligomers using porphyrin pyrrole. Now we report synthesis and properties of conjugated porphyrin oligomers.
