Lin Tingting, Zhang Wei-De, Huang Junchao, He Chaobin
Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602.
J Phys Chem B. 2005 Jul 21;109(28):13755-60. doi: 10.1021/jp051022g.
The first principles density functional theory (DFT) approach (GGA-PW91/DNP) was used to study the addition reaction of methylamine to fullerenes C(50) and C(60) or single-walled carbon nanotubes (SWNTs) (5,5) and (10,0). To understand the relationship between reactivity and curvature, various addition sites have been investigated for comparisons. The DFT calculation results showed that the reaction energy of the addition of methylamine onto C(60) or the closed caps of (5,5) and (10,0) is rather low. Moreover, the reaction at a few sites even appears exothermic. However, the reaction on the perfect sidewall of the nanotubes is always endothermic, and the reaction energy is much higher than that on the caps. The energetically preferable addition sites are the carbon atoms located at the vertexes formed with five-, five-, six-membered rings on C(50) or five-, five-, seven-membered rings on defects of nanotubes. The systematic theoretical study revealed that the pyramidalization and pi-orbital misalignment could result in an increased reactivity of these pentagon-pentagon fusion sites. The reactivity depends on the pyramidalization angle, which is a quantitative measurement of the local curvature and strain of the reaction center.
采用第一性原理密度泛函理论（DFT）方法（GGA-PW91/DNP）研究甲胺与富勒烯C(50)和C(60)或单壁碳纳米管（SWNTs）(5,5)和(10,0)的加成反应。为了理解反应活性与曲率之间的关系，研究了各种加成位点以进行比较。DFT计算结果表明，甲胺加成到C(60)或(5,5)和(10,0)的封闭帽上的反应能量相当低。此外，在一些位点的反应甚至呈现放热。然而，在纳米管完美侧壁上的反应总是吸热的，且反应能量远高于在帽上的反应。能量上更有利的加成位点是位于C(50)上由五、五、六元环形成的顶点处的碳原子，或纳米管缺陷处由五、五、七元环形成的顶点处的碳原子。系统的理论研究表明，锥化和π轨道失准会导致这些五边形-五边形融合位点的反应活性增加。反应活性取决于锥化角，锥化角是反应中心局部曲率和应变的定量度量。
