State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Nat Commun. 2011 Aug 9;2:420. doi: 10.1038/ncomms1431.
A carbon heptagon ring is a key unit responsible for structural defects in sp(2)-hybrized carbon allotropes including fullerenes, carbon nanotubes and graphenes, with consequential influences on their mechanical, electronic and magnetic properties. Previous evidence concerning the existence of heptagons in fullerenes has been obtained only in off-line halogenation experiments through top-down detachment of a C(2) unit from a stable fullerene. Here we report a heptagon-incorporating fullerene C(68), tentatively named as heptafullerene[68], which is captured as C(68)Cl(6) from a carbon arc plasma in situ. The occurrence of heptagons in fullerenes is rationalized by heptagon-related strain relief and temperature-dependent stability. (13)C-labelled experiments and mass/energy conservation equation simulations show that heptafullerene[68] grows together with other fullerenes in a bottom-up fashion in the arc zone. This work extends fullerene research into numerous topologically possible, heptagon-incorporating isomers and provides clues to an understanding of the heptagon-involved growth mechanism and heptagon-dependent properties of fullerenes.
一个七元环碳是负责 sp(2)-杂化碳同素异形体结构缺陷的关键单元，包括富勒烯、碳纳米管和石墨烯，这对它们的力学、电子和磁性能有重要影响。之前关于富勒烯中七元环存在的证据仅在离线卤化实验中通过从稳定的富勒烯中自上而下地去除一个 C(2)单元获得。在这里，我们报告了一种含有七元环的富勒烯 C(68)，暂命名为七元富勒烯[68]，它是通过原位碳弧等离子体捕获的 C(68)Cl(6)。富勒烯中七元环的存在可以通过与七元环相关的应变缓解和温度依赖性稳定性来解释。(13)C 标记实验和质量/能量守恒方程模拟表明，七元富勒烯[68]与电弧区中的其他富勒烯一起以自下而上的方式生长。这项工作将富勒烯研究扩展到了许多可能的拓扑结构中，包括含有七元环的异构体，并为理解富勒烯中涉及七元环的生长机制和七元环依赖的性质提供了线索。
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