Formyl-Porphyrln and formyl-fullerenoporphyrln building blocks for the construction of multlporphyrln arrays

Article abstract of DOI:10.1002/ejoc.200900358

A Eullerene derivative bearing a benzaldehyde unit has been prepared and used as starting material for the synthesis of a formyl-fullerenoporphyrin building block. Condensation of this aldehyde with pyrrole in CHCl₃ with BF₃·Et₂O as catalyst followed by p-chloranil oxidation yielded a pentaporphyrinic scaffold surrounded by four peripheral C₆₀ subunits. By following a similar strategy, a bis-porphyrin building block bearing an aldehyde function was prepared and used for the construction of a nonaporphyrin array by reaction with pyrrole under typical porphyrin synthesis conditions. Whereas the ¹H NMR spectrum recorded at room temperature for the nonaporphyrin system is well defined, the signals recorded under the same conditions for the pentaporphyrin derivative surrounded by four peripheral C₆₀ groups are broad. Indeed, the C ₆₀-pentaporphyrin ensemble appears as a mixture of conformers which equilibrate slowly on the NMR time scale at room temperature.