Van Raden Jeff M, Alexandropoulos Dimitris I, Slota Michael, Sopp Simen, Matsuno Taisuke, Thompson Amber L, Isobe Hiroyuki, Anderson Harry L, Bogani Lapo
Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford OX1 3TA, U.K.
Department of Materials, University of Oxford, Oxford OX1 3PH, U.K.
J Am Chem Soc. 2022 May 18;144(19):8693-8706. doi: 10.1021/jacs.2c02084. Epub 2022 May 3.
The introduction of paramagnetic metal centers into a conjugated π-system is a promising approach toward engineering spintronic materials. Here, we report an investigation of two types of spin-bearing dysprosium(III) and gadolinium(III) porphyrin dimers: singly -linked dimers with twisted conformations and planar edge-fused β,,β-linked tapes. The rare-earth spin centers sit out of the plane of the porphyrin, so that the singly linked dimers are chiral, and their enantiomers can be resolved, whereas the edge-fused tape complexes can be separated into and stereoisomers. We compare the crystal structures, UV-vis-NIR absorption spectra, electrochemistry, EPR spectroscopy, and magnetic behavior of these complexes. Low-temperature SQUID magnetometry measurements reveal intramolecular antiferromagnetic exchange coupling between the Gd centers in the edge-fused dimers ( isomer: = -51 ± 2 MHz; isomer: = -19 ± 3 MHz), whereas no exchange coupling is detected in the singly linked twisted complex. The phase-memory times, , are in the range of 8-10 μs at 3 K, which is long enough to test quantum computational schemes using microwave pulses. Both the and Dy edge-fused tapes exhibit single-molecule magnetic hysteresis cycles at temperatures below 0.5 K with slow magnetization dynamics.
将顺磁性金属中心引入共轭π体系是一种很有前景的制备自旋电子材料的方法。在此，我们报道了对两种含自旋的镝(III)和钆(III)卟啉二聚体的研究：具有扭曲构象的单链二聚体和平面边缘稠合的β,β-连接带。稀土自旋中心位于卟啉平面之外，因此单链二聚体是手性的，其对映体可以拆分，而边缘稠合带配合物可以分离为 和 立体异构体。我们比较了这些配合物的晶体结构、紫外-可见-近红外吸收光谱、电化学、电子顺磁共振光谱和磁行为。低温超导量子干涉仪磁力测量显示，在边缘稠合二聚体中，钆中心之间存在分子内反铁磁交换耦合（ 异构体： = -51 ± 2 MHz； 异构体： = -19 ± 3 MHz），而在单链扭曲配合物中未检测到交换耦合。在3 K时，相位记忆时间 在8 - 10 μs范围内，这足以使用微波脉冲测试量子计算方案。 和 镝边缘稠合带在低于0.5 K的温度下均表现出单分子磁滞回线，且磁化动力学缓慢。
