Hexanuclear manganese(III) single-molecule magnets
Hexanuclear manganese(III) single-molecule magnets
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DOI：
10.1002/anie.200351079
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发表时间：
2004-01-01
影响因子：
16.6
通讯作者：
Escuer, A
中科院分区：
文献类型：
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作者：
Milios, CJ;Raptopoulou, CP;Escuer, A
单分子磁体 (SMM)[1, 2] 是在没有磁场且低于阻断温度的情况下可以保持磁化的分子种类。它们代表了尽可能小的磁存储设备，它将信息保留在单个分子中，而不是磁性颗粒或颗粒阵列中。此外，此类分子跨越经典/量子界面，还表现出磁化的量子隧道效应和量子相位干涉。 SMM 行为源于高自旋基态和大且负（易轴型）磁各向异性的固有分子内特性。[1, 2] 实验上，SMM 在磁化与直流 (dc) 场研究中表现出频率相关的异相交流 (ac) 磁化率 (χ'') 信号和磁滞回线。[1]迄今为止，最好和最广泛研究的 SMM 是十二核物种 [Mn12O12 (O2CR) 16 (H2O) x] nÀ (n= 0, 1, 2; x= 3, 4; MnIII 8 MnIV 4 for n= 0) 及其衍生物，[1, 2]，但还有许多其他含有锰的 SMM 示例（在氧化态） ii/iii、iii/iv 或 ii/iii/iv)、铁、钴、镍和钒。[1-3] SMM 领域的未来重要的是开发新的合成方案，这些方案可以产生具有大自旋和/或各向异性的分子。在此，我们报告了新一类锰基 SMM 的首批成员，其仅由 TB（TB = 阻断温度）大于 2 K 的 MnIII 离子组成。
Single-molecule magnets (SMMs)[1, 2] are molecular species that can retain magnetization in the absence of a magnetic field below a blocking temperature. They represent the smallest possible magnetic storage device, which retains information in a single molecule rather than in a magnetic particle or array of particles. Furthermore, such molecules straddle the classical/quantum interface in also displaying quantum tunneling of magnetization and quantum phase interference. The SMM behavior derives from the intrinsic intramolecular properties of a high-spin ground state, and large and negative (easy axis type) magnetoanisotropy.[1, 2] Experimentally, a SMM exhibits both a frequency-dependent out-of-phase alternating current (ac) magnetic susceptibility (χ’’) signal and hysteresis loops in magnetization versus direct current (dc) field studies.[1] To date, the best and most extensively studied SMMs are the class of the dodecanuclear species [Mn12O12 (O2CR) 16 (H2O) x] nÀ (n= 0, 1, 2; x= 3, 4; MnIII 8 MnIV 4 for n= 0) and their derivatives,[1, 2] but there are a number of other examples of SMMs containing manganese (at the oxidation states ii/iii, iii/iv or ii/iii/iv), iron, cobalt, nickel, and vanadium.[1–3] Important to the future of the field of SMMs is the development of new synthetic schemes that can yield molecules with a large spin and/or anisotropy. Herein we report access to the first members of a new class of manganese-based SMMs consisting exclusively of MnIII ions with TB (TB= blocking temperature) greater than 2 K.