A self-assembled porphyrin-based metallocube, Fe(II)8Por6, has been previously synthesized from tetraaminophenylporphyrin (TAPP), pyridylaldehyde, and Fe(II). This supramolecular metal organic complex has proved useful in encapsulating large aromatic molecules. As we attempt to articulate this chemistry further, it would be advantageous to have an improved synthesis of one of the sub-components, namely the TAPP. It can be made via a classic Adler-Longo porphyrin synthesis starting from nitrobenzaldehyde and pyrrole followed by reduction of the -NO2 to -NH2 using LAH. The procedure typically gives low yields and the products are difficult to purify. In this work we will present results from recent attempts to improve the yield and purity of TAPP. The first alternate procedure involves the synthesis of the acetamidophenylporphyrin from acetamidobenzaldehyde and pyrrole, which can be hydrolyzed to TAPP. The second alternate procedure involves a palladium catalyzed coupling of bromobenzaldehyde and benzyl carbamate to give the O-benzyl-N-formylphenylcarbamate followed by reaction with pyrrole to give a porphyrin that when subjected to hydrogenation is reduced to TAPP. Different methods of purification will also be discussed.

Improved syntheses of tetraaminophenylporphyrin for use in supramolecular metallocubes

253rd National Meeting (2017)

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