Formyl‐Porphyrin and Formyl‐Fullerenoporphyrin Building Blocks for the Construction of Multiporphyrin Arrays

A fullerene 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 CHCl 3 with BF 3 · Et 2 O as catalyst followed by p ‐chloranil oxidation yielded a pentaporphyrinic scaffold surrounded by four peripheral C 60 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 1 H 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 C 60 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.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)