Crystal Packing Effects within [Mn^III _3O]^<7+> Single-Molecule Magnets : Controlling Intermolecular Antiferromagnetic Interactions
Crystal Packing Effects within [Mn^III _3O]^<7+> Single-Molecule Magnets : Controlling Intermolecular Antiferromagnetic Interactions
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[Mn^III _3O]^<7 > 单分子磁体中的晶体堆积效应：控制分子间反铁磁相互作用
DOI：
10.1016/j.poly.2011.05.030
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发表时间：
2011
期刊：
影响因子：
2.6
通讯作者：
and H.-L. Tsai
中科院分区：
文献类型：
--
作者：
C.-I. Yang;K.-H. Cheng;S.-P. Hung;M. Nakano;and H.-L. Tsai
在MeOH中，2-羟基苯乙酮肟（Me-H2salox）和（2-羟基苯基）-苯基甲烷肟（Ph-H2salox）与Mn(ClO4)2·6H2O反应得到[mn30o (Me-salox)3(MeOH)3(ClO4)]·MeOH（1·MeOH）和[mn30o (Ph-salox)3(MeOH)3(ClO4)]·2MeOH（2·2MeOH）的三核锰配合物。x射线分析表明，这两种配合物均含有一个锰三角形核[mniii30]7+。肟配体扭曲的结构扭曲主导了两种化合物中三个Mn离子之间的铁磁相互作用，并导致S=6基态。交流磁化率测量中与频率相关的异相信号、与温度相关的磁滞回线和与扫描速率相关的磁滞回线表明了单分子磁体的行为。此外，这两种配合物都表现出阶梯式磁化，表明存在量子隧穿磁化（QTM）。有趣的是，配合物1·MeOH晶体填料中尾对尾的排列导致了强的分子间氢键相互作用，并导致相邻mn3分子之间的反铁磁相互作用产生交换偏置效应。相反，配合物2·2MeOH的QTM步由于分子间从头到尾的弱相互作用而不存在交换偏置效应。
The reactions of 2-hydroxyphenylethanone oxime (Me-H2salox) and (2-hydroxy-phenyl)-phenyl-methanone oxime (Ph-H2salox) with Mn(ClO4)2·6H2O in MeOH afford trinuclear manganese complexes of [Mn3O(Me-salox)3(MeOH)3(ClO4)]·MeOH (1·MeOH) and [Mn3O(Ph-salox)3(MeOH)3(ClO4)]·2MeOH (2·2MeOH), respectively. X-ray analysis shows that both complexes contain a manganese triangle core, [MnIII3O]7+. The structural distortion from the twisting of the oxime ligands dominates the ferromagnetic interactions within the three Mn ions in both compounds and results in an S=6 ground state. The frequency dependence of out-of-phase signals in the alternating current (AC) magnetic susceptibility measurements and the temperature-dependent and sweep-rate-dependent hysteresis loops are indicative of single-molecule magnet behavior. Moreover, both complexes show step-wise magnetization, indicating the occurrence of quantum tunneling of magnetization (QTM). Interestingly, a tail to tail arrangement in the crystal packing of complex 1·MeOH results in strong intermolecular H-bonding interactions and leads to the exchange-bias effect from the antiferromagnetic interaction between the adjacent Mn3molecules. In contract, QTM steps of complex 2·2MeOH show an absence of the exchange-bias effect due to a weak intermolecular interaction from a head to tail arrangement.