Structure and properties of novel endohedral metallofullerenes

新型内嵌金属富勒烯的结构与性能

基本信息

批准号：
09440198
负责人：
SHINOHARA Hisanori
金额：
$ 9.22万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

Since the first successful purification / isolation of endohedral .metallo-fullerenes many structural and spectroscopic studies on pure metallo-fullerenes have been reported. And yet, purification still remains as one of the most important and crucial parts of metallofullerene studies. This is simply because that the normal yield of metallofullerenes produced by arc discharge is very limited in amount, typically 3 - 5 percent of that of (60. Efficient purification schemes are definitely needed. The two-stage HPLC separation protocol has been proven to be a useful. method for isolating various types of metallofullerenes although the current HPLC columns for fullerene separation are fairly expensive.By using these highly purified samples, structural studies have been performed. Endohedral structures of Y@C82 (I) and 5c2@C84 (III) have been finally confirmed by synchrotron powder X-ray diffraction studies with the Rietveld / MEM (maximum entropy method) analysis, where such information as the nearest metal-carbon and Sc - Sc distances were obtained. However, the isomer structures of these metallofullerenes have not yet determined.High resolution 13C-NMR experiments, on the other hand, have so far provided us detailed information on isomer structures of fullerenes. Here, we present 13C-NMR results for the isomer structures of Sc2@C84 (isomer III) and Ca@C82 (isomer III) as examples. In fact, the presence of structural isomers of endohedral metallofullerenes (like empty higher fullerenes) has been confirmed, for the first time, by these 13C-NMR experiments.Some useful criteria for interpreting UV-Vis-near IR absorption spectra of mono-metallofullerenes will be discussed in the final part of the present article.

自从首次成功纯化/分离内嵌金属富勒烯以来，已经报道了许多关于纯金属富勒烯的结构和光谱研究。然而，纯化仍然是金属富勒烯研究中最重要和最关键的部分之一。这仅仅是因为电弧放电产生的金属富勒烯的正常产量非常有限，通常为 (60) 的 3 - 5%。绝对需要有效的纯化方案。两级 HPLC 分离方案已被证明是尽管目前用于富勒烯分离的 HPLC 柱相当昂贵，但这是一种分离各种类型金属富勒烯的有用方法。通过使用这些高度纯化的样品，已经进行了内嵌结构的研究。 Y@C82 (I) 和 5c2@C84 (III) 最终通过同步加速器粉末 X 射线衍射研究和 Rietveld / MEM（最大熵法）分析得到证实，其中最接近的金属-碳和 Sc - Sc 等信息然而，这些金属富勒烯的异构体结构尚未确定。另一方面，高分辨率13C-NMR实验迄今为止为我们提供了异构体结构的详细信息。在这里，我们以 Sc2@C84（异构体 III）和 Ca@C82（异构体 III）的异构体结构为例，展示 13C-NMR 结果。事实上，这些 13C-NMR 实验首次证实了内嵌金属富勒烯（如空的高级富勒烯）结构异构体的存在。解释单金属富勒烯的紫外-可见-近红外吸收光谱的一些有用标准将在本文的最后部分讨论。