Recognition of Hydrogen Isotopomers by an Open-Cage Fullerene
Recognition of Hydrogen Isotopomers by an Open-Cage Fullerene
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开笼富勒烯识别氢同位素异构体
DOI：
10.1098/rsta.2011.0629
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
K.
中科院分区：
文献类型：
--
作者：
Murata;Y.; Chuang;S.-C.; Tanabe;F.; Murata;M.; Komatsu;K.
通过测定H_2/HD/D_2与开笼富勒烯的结合亲和力，并通过动力学释放实验比较它们的相对分子大小，研究了开笼富勒烯对氢同位素的识别.我们利用同位素H2/D2交换在不锈钢高压釜中产生H2/HD/D2平衡混合物的优势，对开笼富勒烯进行高压氢嵌入。在不同压力和温度下测定了三种同位素与开笼富勒烯的平衡常数。我们的研究结果表明，HD到开笼富勒烯比其他两个同位素异构体，这是符合其偶极性质的平衡常数。D2分子由于其较重的质量，通常比H2结合更强;然而，在较低温度下，当尺寸效应占主导地位时，对H2的亲和力变得大于D2。我们进一步研究了H2/HD/D2从开笼富勒烯中释放的动力学，证明了它们的相对逃逸速率。D2是最小的分子，H2是最大的分子。这一观点不仅支持了所观察到的H2和D2之间的相对结合亲和力的反转，而且还证明了通过非共价动力学同位素效应比较单个分子的大小差异是适用的。
We present our study on the recognition of hydrogen isotopes by an open-cage fullerene through determination of binding affinity of isotopes H2/HD/D2with the open-cage fullerene and comparison of their relative molecular sizes through kinetic-isotope-release experiments. We took advantage of isotope H2/D2exchange that generated an equilibrium mixture of H2/HD/D2in a stainless steel autoclave to conduct high-pressure hydrogen insertion into an open-cage fullerene. The equilibrium constants of three isotopes with the open-cage fullerene were determined at various pressures and temperatures. Our results show a higher equilibrium constant for HD into open-cage fullerene than the other two isotopomers, which is consistent with its dipolar nature. D2molecule generally binds stronger than H2because of its heavier mass; however, the affinity for H2becomes larger than D2at lower temperature, when size effect becomes dominant. We further investigated the kinetics of H2/HD/D2release from open-cage fullerene, proving their relative escaping rates. D2was found to be the smallest and H2the largest molecule. This notion has not only supported the observed inversion of relative binding affinities between H2and D2, but also demonstrated that comparison of size difference of single molecules through non-convalent kinetic-isotope effect was applicable.