the Magneto-Chiral Dichroism (MChD) detected up to 5 T through Visible and Near Infrared light absorption of {Er5Ni6} metal clusters obtained by reaction of enantiopure chiral ligands, namely (R/S)-(2-hydroxy-3-methoxybenzyl)-serine) and NiII and ErIII precursors is reported. Single-crystal diffraction analysis reveals that these compounds are 3d-4f heterometallic clusters showing helical chirality. They are isostructural to the recently reported {Ln5Ni6}(Ln = DyIII, YIII) chiral clusters that have shown multi-metal site MChD. The analysis of absorption and MChD spectra show a high gMChD dissymmetry factor of ca. 0.24 T-1 (T = 4.0 K, B = 1.0 T) for the 4I15/2 ← 4I13/2 magnetic-dipole allowed electronic transition of the ErIII centers. This record value is an order of magnitude higher than that observed for the electronic transition of the DyIII centers in an isostructural analogue. The d-d electronic transitions of the NiII ions and the other f-f electric-dipole induced transitions of ErIII centers provide gMChD factors one or two order of magnitude lowers. These findings clearly show the key role of magnetic-dipole allowed transitions for high MChD effects in lanthanide-based systems, paving for a rational design for original highly MChD responsive chiral lanthanide systems.
- Enhancement of Magneto-Chiral Dichroism Intensity by Chemical Substitution : The Key Role of Magnetic-Dipole Allowed Transitions
C. Y. Li, L. C. Adi, K. Paillot, I. Breslavetz, L. S. Long, L. S. Zheng, G. L. J. A. Rikken, C. Train, X.-J. Kong* et M. Atzori* J. Am. Chem. Soc. 2024, 146, (doi : 10.1021/jacs.4c06503)
https://pubs-acs-org.inp.bib.cnrs.fr/doi/10.1021/jacs.4c06503