Halterman corroles and their use as a probe of the conformational dynamics of the inherently chiral copper corrole chromophore

Thomas, Kolle E., McCormick, Laura J., Carrié, Daniel, Vazquez-Lima, Hugo, Simonneaux, Gérard and Ghosh, Abhik (2018) Halterman corroles and their use as a probe of the conformational dynamics of the inherently chiral copper corrole chromophore. Inorganic Chemistry, 57 (8), 4270-4276. (doi:10.1021/acs.inorgchem.7b02767).

Abstract

Halterman corroles have been synthesized for the first time from pyrrole and Halterman's aldehyde via Gryko's "water-methanol method". These were derivatized to the corresponding copper complexes and subsequently to the β-octabromo complexes. Electronic circular dichroism spectra were recorded for the enantiopure copper complexes, affording the first such measurements for the inherently chiral Cu corrole chromophore. Interestingly, for a given configuration of the Halterman substituents, X-ray crystallographic studies revealed both P and M conformations of the Cu-corrole core, proving that the substituents, even in conjunction with β-octabromination, are unable to lock the Cu-corrole core into a given chirality. The overall body of evidence strongly indicates a dynamic equilibrium between the P and M conformations. Such an interconversion, which presumably proceeds via saddling inversion, provides a rationale for our failure so far to resolve sterically hindered Cu corroles into their constituent enantiomers by means of chiral HPLC.

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Contributors

Author: Laura J. McCormick

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