Carbene spacers in bis-porphyrinic scaffolds.

The preparation of two meso-imidazolylporphyrins was achieved in good yield by Ullmann coupling between a meso-bromotriarylporphyrin and imidazoles. Subsequent alkylation afforded the corresponding imidazolium functionalized porphyrins as direct precursors of the carbene. The complexation of these azolium salts with palladium led to trans-anti bis-porphyrin carbenic complexes.