Chiral amine enantiomeric excess determination using self-assembled octahedral Fe(II)-imine complexes.

A receptor assembly composed of iron(II) triflate and pyridine-2,6-dicarbaldehyde was used to determine the enantiomeric excess (ee) of alpha-chiral primary amines using circular dichroism spectroscopy. The alpha chiral amines condense with the dialdehyde to form a diimine, which forms a 2:1 octahedral complex with iron(II). The ee values of unknown concentrations of alpha-chiral amines were determined by constructing calibration curves for each amine and then measuring the ellipticity at 600 nm. This improves our previously reported assay for ee determination of chiral primary amines by further increasing the wavelength at which CD is measured and reducing the absolute error of the assay.