meso ‐Diketopyripentaphyrin and Diketopyrihexaphyrin as Macrocyclic Tripyrrinone Ligands for Ni II Ions

We report expanded porphyrins with pyridine rings and two neighboring carbonyl groups, which allow Ni II ions to coordinate to the tripyrrinone‐type NNNO coordination structure with Ni−O bonds. The selectivity of tripyrrinone is superior to other pyrrolic or pyridinic cavities of expanded porphyrins. Introduction of α‐carbonyl pyridine next to the tripyrrolic conjugated structure is a powerful strategy for regioselective metalation of flexible expanded porphyrinoids.