Matxain Jon M, Formoso Elena, Mercero Jose M, Piris Mario, Lopez Xabier, Ugalde Jesus M
Kimika Fakultatea, Euskal Herriko Unibertsitatea and Donostia International Physics Center, Donostia, Euskadi, Spain.
Chemistry. 2008;14(28):8547-54. doi: 10.1002/chem.200800376.
Endohedral first-row transition-metal-doped TM@Zn(i)S(i) nanoclusters, in which TM stands for the first-row transition-metals from Sc to Zn, and i=12, 16, have been characterized. In these structures the dopant metals are trapped inside spheroidal hollow semiconducting nanoclusters. It is observed that some of the transition metals are trapped in the center of mass of the cluster, whereas others are found to be displaced from that center, leading to structures in which the transition metals display a complex dynamical behavior upon encapsulation. This fact was confirmed by quantum molecular dynamics calculations, which further confirmed the thermal stability of endohedral compounds. In the endohedrally-doped nanoclusters in which the transition-metal atom sits on the center of mass, the host hollow cluster structure remains undistorted after dopant encapsulation. Conversely, if the encapsulated transition-metal atom is displaced from the center of mass, the host hollow cluster structure suffers a very tiny distortion. Additionally, it is found that there is negligible charge transfer between the dopant transition-metal atom and its hollow cluster host and, after encapsulation, the spin densities remain localized on the transition-metal atom. This allows for the atomic-like behavior of the trapped transition-metal atom, which gives rise to their atomic-like magnetic properties. The encapsulation free energies are negative, suggesting that these compounds are thermodynamically stable.
内包第一行过渡金属掺杂的TM@Zn(i)S(i)纳米团簇已被表征，其中TM代表从Sc到Zn的第一行过渡金属，i = 12、16。在这些结构中，掺杂金属被困在球形中空半导体纳米团簇内部。据观察，一些过渡金属被困在团簇的质心，而其他过渡金属则偏离该中心，导致过渡金属在封装后呈现复杂动力学行为的结构。这一事实通过量子分子动力学计算得到证实，该计算进一步证实了内包化合物的热稳定性。在过渡金属原子位于质心的内包掺杂纳米团簇中，掺杂剂封装后主体中空团簇结构保持不变。相反，如果封装的过渡金属原子偏离质心，主体中空团簇结构会遭受非常微小的变形。此外，发现掺杂的过渡金属原子与其中空团簇主体之间的电荷转移可忽略不计，并且封装后自旋密度仍局限于过渡金属原子上。这使得被困过渡金属原子具有类原子行为，从而产生其类原子磁性。封装自由能为负，表明这些化合物在热力学上是稳定的。
