【作者】 金莲姬；

【导师】 苏忠民；

【作者基本信息】 东北师范大学 ， 物理化学， 2006， 硕士

【摘要】 Kroto等人在1985年首次发现了C₆₀分子,Kraetschmer等人在1990年实现了其宏观量生产。1991年S.Iijima等人发现了碳纳米管。从此,富勒烯和碳纳米管所具有的独特结构与性质将人们带入崭新的材料科学领域,也充分引起了科学家们广泛的注意。1991年,第一个富勒烯包合物La@C₈₂制备成功后,不仅掀起了富勒烯包合物的研究热潮,而且纳米微孔材料的中空管特性也使得人们想象在微孔介质中吸附存储氢气、天然气以及其他一些有机小分子气体。本文用密度泛函理论（DFT） B3LYP方法,对富勒烯有机小分子包合物（C₂H₂@C₆0、C₂H₄@C₆0和C₂H₆@C₆0）和内包合有机小分子的碳纳米管复合物（C2H2@（5,5）SWNT、C₂H₄@（5,5）SWNT和C₂H₆@（5,5）SWNT）分别进行了理论研究。其主要研究结果如下:1.有机小分子在碳笼的中心时包合物最稳定。在这种包合物中有机小分子是电子的受体,而碳笼则为电子的给体,这与金属富勒烯包合物恰恰相反。前线分子轨道分析和结合能分析都表明,这种包合物的形成过程为吸热过程。虽然碳笼和有机小分子之间存在着排斥作用,且这种排斥作用引起了碳笼的形变和有机小分子键长的缩短,但并没有破坏其笼状结构。这说明理论上C₆₀可以很好地存储C₂H₂, C₂H₄和C₂H₆等有机小分子在其笼里。但是因为它们之间有相互排斥作用,在实验合成时,如果将C₆₀换成直径大于9（?）的高碳笼或者采用化学开笼等特殊的合成方法会取得更佳效果。2.中心掺杂物放在碳纳米管的管轴上的异构体相对于掺杂物垂直于管轴的异构体要稳定。结合能研究预测内嵌有机小分子碳纳米管复合物的形成过程为吸热过程;前线分子轨道研究表明有机小分子的插入会使其HOMO-LUMO能隙变大;有机小分子的插入会引起碳纳米管直径的轻微加大,来减少碳管张力,其形变程度按C₂H₂、C₂H₄、C₂H₆的顺序依次增大;外围碳纳米管的存在会使内嵌小分子的C-C、C-H键长受到轻微压缩,对键长的压缩程度也按内嵌的分子为C₂H₂、C₂H₄、C₂H₆的顺序依次增大;电荷分析结果表明极微量电荷会从碳管转移到内嵌的有机小分子,且其电荷转移量按内嵌的分子为C₂H₂、C₂H₄、C₂H₆的顺序依次增大。更多还原

【Abstract】 Kroto et al discovered the Buckminster-fullerene in 1985 and Kraetschmer et al succeeded in producing macroscopic quantities of C₆₀ in 1990. In the next year, carbon nanotubes were discovered by S. Iijima. Then, the unique structure and properties of C60 and carbon nanotubes attracted considerable attention and lead people to the novel fields of materials. Since the first endohedral metallofullerenes, La@C₈₂ was discovered in 1991, there has been much interest in studying not only endohedral fullerene but also endohedral carbon nanotube which could be ideal container for some small molecules such as H₂, CH₄ and so on.In this paper, endohedrally acetylene, ethylene and ethane doped fullerene （C₂H₂@C₆0, C₂H₄@C₆0 and C₂H₆@C₆0） and single-walled carbon nanotube（C₂H₂@（5,5）SWNT, C₂H₄@（5,5）SWNT and C₂H₆@（5,5）SWNT） were studied theoretically using Density Functional Theory （DFT） at B3LYP leveal, respectively. The main results are as follow:1. When the dopant sited at the center of the C60 cage, the energy of complex is at its minimum. The dopant is an electron acceptor and the cage is a donor which is different from the case of metallofullerenes. The frontier orbital analysis and the binding energy calculations suggest that the formations of C₂H₂@C₆0, C₂H₄@C₆0 and C₂H₆@C₆0 would be endothermic. The cage and dopant affect each other rarely except for the slight distortion of C₆0 cage and compression of the hydrocarbon molecules. Apparently, C₆0 could be a good container for some small hydrocarbon molecules like C₂H₂, C₂H₄ and C₂H₆ theoretically. But it may be more practical experimentally if the cage would be higher fullerenes whose diameter are larger than 9（?） or use some special synthetic routes similar to opening a hole in the fullerene through chemical modification.2. The isomer in which the dopant is parallel to the wall of SWNT is more stable than that of normal to the wall. The calculations suggests that the formations of C₂H₂@（5,5）SWNT, C₂H₄@（5,5）SWNT and C₂H₆@（5,5）SWNT are endothermic; The frontier molecular orbital analysis shows that doping hydrocarbon molecule made the increasment of the HOMO-LUMO gap; the insertion of the hydrocarbon molecule in the center of the nanotube enlarge the diameter of the nanotube and the nanotube outside made the C-C and C-H bond lengths of hydrocarbon molecule compressed slightly and the bigger the dopant is, the tighter the compression is; a small quantity of electron transfer from （5,5）SWNT to the hydrocarbon molecule happenes and the amount of the electron transfer in the three compounds is the following sequence of C₂H₂@（5,5）SWNT<C₂H₄@（5,5）SWNT<C₂H₆@（5,5）SWNT.更多还原