Strong and Switchable Magneto-Optical Effect in Air-Stable Chiral Dy^III Complexes with Magnetic Anisotropy

Assembling chiral and magnetic units at a molecular level is a key to achieving a strong magneto-optical (MO) effect, especially for lanthanide complexes with a specific 4f electronic configuration. However, the f-f transitions are generally restricted by selection rules, making the observation of the MO response extremely challenging. Herein, we reported the synthesis of two highly air-stable chiral Dy^III complexes 1-R and 1-S, with a pair of tailored chelating chiral ligands. Besides magnetization dynamics in a wide temperature range, the magnetic circular dichroism (MCD) of 1-R and 1-S shows remarkable MO responses of f-f transitions of Dy^III centers in the vis-NIR region, and CD spectra of 1-R and 1-S provide the first experimental observation of room-temperature CD peaks corresponding to the f-f transition of Dy^III at 450 nm. Importantly, the direction of CD signals from 700 to 1100 nm can be reversibly switched by external magnetic fields. Mechanism study reveals that the strong magnetic anisotropy of the Dy^III center is a key to inducing the remarkable room-temperature MO effect. This work not only provides a facile way to construct air-stable magnetic and chiral complexes but also gains insights into the influence of magnetic anisotropy on the strong MO effect in a wide spectrum range at room temperature.