Department of Chemistry, Columbia University, New York, New York 10027, USA.
J Am Chem Soc. 2011 Sep 14;133(36):14232-5. doi: 10.1021/ja206383n. Epub 2011 Aug 19.
The photochemical interconversion of the two allotropes of the hydrogen molecule [para-H(2) (pH(2)) and ortho-H(2) (oH(2))] incarcerated inside the fullerene C(70) (pH(2)@C(70) and oH(2)@C(70), respectively) is reported. Photoexcitation of H(2)@C(70) generates a fullerene triplet state that serves as a spin catalyst for pH(2)/oH(2) conversion. This method provides a means of changing the pH(2)/oH(2) ratio inside C(70) by simply irradiating H(2)@C(70) at different temperatures, since the equilibrium ratio is temperature-dependent and the electronic triplet state of the fullerene produced by absorption of the photon serves as an "on-off" spin catalyst. However, under comparable conditions, no photolytic pH(2)/oH(2) interconversion was observed for H(2)@C(60), which was rationalized by the significantly shorter triplet lifetime of H(2)@C(60) relative to H(2)@C(70).
报道了在富勒烯 C（70）内囚禁的氢分子的两种同素异形体[para-H（2）（pH（2））和 ortho-H（2）（oH（2））]的光化学互变。H（2）@C（70）的光激发产生了富勒烯三重态，它可作为 pH（2）/oH（2）转化的自旋催化剂。通过简单地在不同温度下辐照 H（2）@C（70），这种方法提供了一种改变 C（70）内 pH（2）/oH（2）比例的方法，因为平衡比例取决于温度，并且吸收光子产生的富勒烯的电子三重态充当“开/关”自旋催化剂。然而，在可比条件下，对于 H（2）@C（60），没有观察到光解 pH（2）/oH（2）互变，这可以通过 H（2）@C（60）的三重态寿命明显短于 H（2）@C（70）来合理化。
