Syntheses and optical and electrochemical properties of porphyrin dimers linked by metal ions

The preparation, isolation, and characterization of several new peripherally functionalized monomeric porphyrins and metalloporphyrins and of porphyrin dinners are described. These dinners are obtained by linking with metal ions two monomeric porphyrins bearing at their periphery an enaminoketone chelate fully conjugated with the aromatic ring. Porphyrin dinners linked by metal ions display large interactions in the ground state as evidenced by their electronic spectra and their electrochemical behavior. Compared to the monomeric analogue, these dinners show absorption spectra with intensified red-shifted Q-bands and their first oxidation potentials are substantially lowered and split into two distinct redox steps.