Carbon cage isomers and magnetic Dy⋯Dy interactions in Dy2O@C88 and Dy2C2@C88 metallofullerenes
Carbon cage isomers and magnetic Dy⋯Dy interactions in Dy2O@C88 and Dy2C2@C88 metallofullerenes
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Dy2O@C88 和 Dy2C2@C88 金属富勒烯中的碳笼异构体和磁性 Dy–Dy 相互作用
DOI：
10.1039/d2qi01796b
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
Chen Ning
中科院分区：
文献类型：
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作者：
Yang Wei;Velkos Georgios;Sudarkova Svetlana;Büchner Bernd;Avdoshenko Stanislav M;Liu Fupin;Popov Alexey A.;Chen Ning
合成了三种Dy2O@C88异构体和两种Dy2C2@C88异构体，并通过单晶X射线衍射、振动光谱和密度泛函理论对其结构进行了表征。这两种类型的簇富勒烯都具有4重电子转移到碳笼的特征，因此产生了相同的碳笼异构体，分别为C1（26），Cs（32）和D2（35）。对Dy 2 O和Dy 2C 2团簇中Dy → Dy超交换相互作用的研究表明，O2−桥有利于反铁磁耦合，而乙炔基C22−支持Dy磁矩的铁磁耦合。偶联的强度在不同的笼异构体中表现出相当大的变异性。所有的金属富勒烯表现出缓慢的弛豫磁化和磁滞。在Dy2O@C88异构体中，滞后在7-9 K时保持开放，而在Dy2C2@C88中，滞后环在2.5 K时已经闭合。研究表明，金属原子间的内嵌桥和富勒烯笼在磁相互作用和磁化弛豫中起着重要作用。
Three isomers of Dy2O@C88 and two isomers of Dy2C2@C88 were synthesized and structurally characterized by single-crystal X-ray diffraction, vibrational spectroscopy, and DFT calculations. Both types of clusterfullerenes feature 4-fold electron transfer to the carbon cage, thus resulting in the same carbon cage isomers identified as C1(26), Cs(32), and D2(35). The studies of Dy⋯Dy superexchange interactions in Dy2O and Dy2C2 clusters revealed that the O2− bridge favors antiferromagnetic coupling whereas the acetylide group C22− supports ferromagnetic coupling of Dy magnetic moments. The strength of the coupling showed a considerable variability in different cage isomers. All metallofullerenes exhibited slow relaxation of magnetization and magnetic hysteresis. In Dy2O@C88 isomers the hysteresis remained open up to 7–9 K, while in Dy2C2@C88 the hysteresis loops were closed already at 2.5 K. This study demonstrated that both the endohedral bridge between metal atoms and the fullerene cage play an important role in magnetic interactions and relaxation of magnetization.