Title
Halterman Corroles and Their Use as a Probe of the Conformational Dynamics of the Inherently Chiral Copper Corrole Chromophore
Author
Kolle E. Thomas, Laura J. McCormick, Daniel Carrié, Hugo Vazquez-Lima, Gérard Simonneaux, Abhik Ghosh
Year
2018
Journal
Inorganic Chemistry
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 Mconformations 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.
Instrument
J-825
Keywords
Circular dichroism, Soret band, Stereochemistry, Inorganic chemistry