Demonstration of a chemical transformation inside a fullerene. The reversible conversion of the allotropes of H2@C60.
Demonstration of a chemical transformation inside a fullerene. The reversible conversion of the allotropes of H2@C60.
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DOI：
10.1021/ja804311c
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发表时间：
2008-07
影响因子：
15
通讯作者：
N. Turro;A. Martí;J. Y. Chen;S. Jockusch;R. Lawler;M. Ruzzi;E. Sartori;Shih‐Ching Chuang;K. Komatsu;Y. Murata
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文献类型：
--
作者：
N. Turro;A. Martí;J. Y. Chen;S. Jockusch;R. Lawler;M. Ruzzi;E. Sartori;Shih‐Ching Chuang;K. Komatsu;Y. Murata
报道了固定在富勒烯C60中的氢分子的两种同素异形体(对位-H2和邻位-H2)的相互转化(分别为oH2@C60和ph2@C60)。对于转化，OH2@C60被吸附在NaY分子筛的外表面，并在77K下浸泡在液氧中，在不到0.5h的时间内达到平衡，快速脱氧提供了在没有顺磁催化剂的情况下稳定数天的富PH2@C60样品(半衰期约为15天)。浓缩的PH2@C60不挥发，易溶于有机溶剂。在室温下，在顺磁催化剂(溶解O2或氮氧化物TEMPO)的存在下，用1H核磁共振观察到了缓慢的反转化为oH2@C60。在kTempo约为4×10~(-5)M~(-1)S~(-1)的条件下，观察到Ph_2@C_(60)转化为O_H_2@C_(60)的双分子速率常数，比不受C_(60)壳层保护的有机溶剂中Ph_2的双分子速率常数慢约3个数量级。
The interconversion of the two allotropes of the hydrogen molecule (para-H2 and ortho-H2) incarcerated inside the fullerene C60 is reported (oH2@C60 and pH2@C60, respectively). For conversion, oH2@C60 was adsorbed at the external surface of the zeolite NaY and immersed into liquid oxygen at 77 K. Equilibrium was reached in less than 0.5 h. Rapid removal of oxygen provides a sample of enriched pH2@C60 that is stable for many days in the absence of paramagnetic catalysts (half-life approximately 15 days). Enriched pH2@C60 is nonvolatile and soluble in organic solvents. At room temperature in the presence of a paramagnetic catalyst (dissolved O2 or the nitroxide Tempo) a slow back conversion into oH2@C60 was observed by 1H NMR. A bimolecular rate constant for conversion of pH2@C60 to oH2@C60 using Tempo of kTempo approximately 4 x 10-5 M-1 s-1 was observed, which is approximately 3 orders of magnitudes slower than that for dissolved pH2 in organic solvents which is not protected by the C60 shell.