Porphyrins,especially tetraphenylporphyrins (TPPs),have been intensively studied and used in various fields.In recent years,larger congeners of porphyrins,known as expanded porphyrins have been of interest because of a variety of unique properties.However,although ring-contracted boron-stabilized azaporphyrins,that is,subphthalocyanines,are known (l),ring-contracted congeners were unknown until the recent synthesis of the boron-containing tribenzosubpor-phyrin 2 by Osuka et al.'
展开▼
