Photochemically Tuned Magnetic Properties in an Erbium(III)-Based Easy-Plane Single-Molecule Magnet

The magnetic properties of single-molecule magnets can be controlled by external conditions such as light, pressure, and temperature. Among these conditions, photochemical control is the best approach due to the accessibility and rapid conduction of light. In this work, an Er(III)-based complex with photoactive ligand bpe, [Er(nat)₃·MeOH·bpe] (1, bpe = 1,2-bis(2-pyridyl)ethylene, nat = 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione), was synthesized. The auxiliary ligand nat and cyclized ligand bpe stacked reasonably in the crystal structure. Two molecules of 1 experienced the [2, 2]-cycloaddition reaction under the UV irradiation in the solid state and [{Er(nat)₃MeOH}₂(tpcb)] (2, tpcb = tetrakis(4-pyridyl)cyclobutane) was produced. The slight change in the structure around Er(III) ions leads to the different magnetic properties, which illustrates the photochemical control of the magnetic properties of single-molecule magnets.