Magneto-chiral dichroism of chiral lanthanide complexes

Abstract

Magneto-Chiral Dichroism (MChD) is an enantioselective and polarization independent light–matter interaction shown by magnetized chiral molecules and materials. This phenomenon, predicted in 1984 and experimentally demonstrated in 1997 by studying the differential visible light emission of a chiral Eu^III complex, is now attracting the interest of the chemical community working with transition metal and lanthanide-based chiral complexes. This is motivated by both the information on the magnetic, electronic and chiroptical properties that can be retrieved using this unconventional spectroscopic technique and the potential technological applications that can be foreseen, such as the optical readout of magnetic data without the need for polarization-based readout devices. In particular, chiral lanthanide complexes, which intrinsically have high spin–orbit coupling (a key factor to observe MChD), a variety of electronic configurations, a multitude of electronic transitions of different characteristics, variable coordination geometries and different degrees of magnetic anisotropy, represent ideal molecules to investigate MChD in both light absorption and emission in a wide spectral range. This perspective summarizes the studies reported so far in the literature on the MChD of chiral lanthanide complexes and provides some general conclusions that will help the chemical community in designing lanthanide-based systems highly responsive to MChD. Finally, we suggest prospective experiments and studies that are needed to push forward the understanding and the use of this fascinating phenomenon.