Undecaphenylcorroles

A first major study of undecaphenylcorrole (UPC) derivatives is presented. Three different Cu-UPC derivatives with different para substituents X (X = CF3, H, CH3) on the β-aryl groups were synthesized via Suzuki–Miyaura coupling of Cu­[Br8TPC] and the appropriate arylboronic acid. A single-crystal X-ray structure of the X = CF3 complex revealed a distinctly saddled macrocycle conformation with adjacent pyrrole rings tilted by ∼60–66° relative to one another (within the dipyrromethane units), which is somewhat higher than that observed for β-unsubstituted Cu-TPC derivatives but slightly lower than that observed for Cu­[Br8TPC] (∼70°) derivatives. Electrochemical and electronic absorption measurements afforded some of the first comparative insights into meso versus β substituent effects on the copper corrole core. The Soret maxima of the Cu-UPC complexes (∼440–445 nm), however, are comparable to those of Cu­[Br8TPC] derivatives and are considerably red-shifted relative to Cu-TPC derivatives. Para substituents on the β-phenyl groups were found to tune the redox potentials of copper corroles more effectively than those on meso-phenyl substituents, a somewhat surprising observation given that neither the HOMO nor LUMO has significant amplitudes at the β-pyrrolic positions.