Otto-Diels-Institute for Organic Chemistry, University of Kiel, 24118-Kiel, Germany.
Science. 2011 Jan 28;331(6016):445-8. doi: 10.1126/science.1201180.
Magnetic bistability, as manifested in the magnetization of ferromagnetic materials or spin crossover in transition metal complexes, has essentially been restricted to either bulk materials or to very low temperatures. We now present a molecular spin switch that is bistable at room temperature in homogeneous solution. Irradiation of a carefully designed nickel complex with blue-green light (500 nanometers) induces coordination of a tethered pyridine ligand and concomitant electronic rearrangement from a diamagnetic to a paramagnetic state in up to 75% of the ensemble. The process is fully reversible on irradiation with violet-blue light (435 nanometers). No fatigue or degradation is observed after several thousand cycles at room temperature under air. Preliminary data show promise for applications in magnetic resonance imaging.
磁性双稳性，如在铁磁材料的磁化或过渡金属配合物的自旋交叉中表现出的，本质上局限于块状材料或极低温度。我们现在展示一种在均相溶液中室温下具有双稳性的分子自旋开关。用蓝绿光（500 纳米）辐照精心设计的镍配合物会诱导桥联吡啶配体的配位，并使配合物从顺磁态到高达 75%的顺磁态的电子重排。该过程在用紫光-蓝光（435 纳米）辐照时完全可逆。在室温下空气中经过几千个循环后，没有观察到疲劳或降解。初步数据显示在磁共振成像应用中有应用前景。
