Purification of endohedral trimetallic nitride fullerenes in a single, facile step
Purification of endohedral trimetallic nitride fullerenes in a single, facile step
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DOI：
10.1021/ja055089t
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发表时间：
2005-11-23
影响因子：
15
通讯作者：
Dorn, HC
中科院分区：
文献类型：
--
作者：
Ge, ZX;Duchamp, JC;Dorn, HC
阻碍富勒烯、面内金属富勒烯和纳米管发展的一个主要障碍是难以获得高纯度的样品。通过Kratschmer-Huffman电弧发生器以常规方式制备的碳烟由不溶性碳质材料和可溶性富勒烯的混合物组成：C(60)、C(70)、C(76)、C(78)、C(84)等。当金属作为面内物种引入时，生成的碳烟的复杂性甚至更大，因为空富勒烯和面内金属富勒烯都存在多种异构体。在此，我们首次报道了稀土三金属氮化物金属富勒烯A(3)N@C(80)(A=稀土原子，如Er，Gd，Ho，Lu，Sc，Tb，Tm，Y)，可以利用它们相对于其他富勒烯在Diels-Alder反应中与环戊二烯官能化树脂发生Diels-Alder反应的非凡的动力学化学稳定性，在一步简单的步骤中直接得到纯净的形式。我们表明，仔细控制条件(化学计量、时间、温度)可以分离不同笼子大小的富勒烯以及同分异构体。此外，Diels-Alder反应是热可逆的，我们证明了结合的空笼富勒烯和经典的包体金属富勒烯可以通过马来酸酐置换来恢复。
A major hurdle hampering the development of fullerenes, endohedral metallofullerenes, and nanotubes has been the difficulty of obtaining high purity samples. Soots prepared in the usual manner via a Kratschmer-Huffman electric-arc generator consist of mixtures of insoluble carbonaceous materials and soluble fullerenes: C(60), C(70), C(76), C(78), C(84), etc. When metals are introduced as endohedral species the complexity of the resultant soot is even greater because of the presence of multiple isomers of both the empty fullerenes and the endohedral metallofullerenes. Here, for the first time, we report that lanthanide trimetallic nitride endohedral metallofullerenes, A(3)N@C(80) (A = lanthanide atom, e.g., Er, Gd, Ho, Lu, Sc, Tb, Tm, Y), can be obtained in pure form directly from as-prepared soots in a single facile step by taking advantage of their extraordinary kinetic chemical stability with respect to the other fullerenes in Diels-Alder reactions with a cyclopentadiene-functionalized resin. We show that careful control of conditions (stoichiometry, time, temperature) allows separation of fullerenes with different cage sizes, as well as isomeric species. Furthermore, the Diels-Alder reaction is thermally reversible, and we demonstrated that the bound empty-cage fullerenes and classical enclohedral metallofullerenes can be recovered by displacement with maleic anhydride.