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Eighteen possible isomers of C78(CH2)2 weTe investigated by the INDO method. It was indicated that the most stable isomer was 42,43,62,63-C78(CH2)2, where the -CH2 groups were added to the 6/6 bonds located at the same hexagon passed by the longest axis of C78 (C2v), to form cyclopropane structures. Based on the most stable four geometries of C78(CH2)2 optimized at B3LYP/3-21G level, the first absorptions in the electronic spectra calculated with the INDO/CIS method and the IR frequencies of the C-C bonds on the carbon cage computed using the AM1 method were blue-shifted compared with those of C78 (C2v) because of the bigger LUMO-HOMO energy gap and the less conjugated carbon cage after the addition. The chemical shifts of ^13C NMR for the carbon atoms on the added bonds calculated at B3LYP/3-21G level were moved upfield thanks to the conversion from sp^2-C to sp^3-C. 相似文献
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以苯乙烯桥联的三苯烯分子为模型化合物, 自行设计一系列分子, 用半经验AM1方法和密度泛函理论在B3LYP/3-21G水平上对其进行结构优化. 在B3LYP/3-21G优化构型基础上, 用INDO/CIS和B3LYP/3-21G方法计算其电子吸收光谱和碳原子化学位移. 结果表明, 母体化合物中取代基的数目、供电子能力和立体效应将影响其LUMO-HOMO(最低空轨道-最高占据轨道)能隙、空穴注入性能及热稳定性. —CN和—OH的存在将使化合物电子吸收光谱的第一吸收峰及主要吸收峰与母体相比发生红移. —CN上的C原子受N原子影响化学位移出现在低场, 与—CN相连的C原子由于具有较大的电子云密度化学位移向高场移动, 骨架上的C原子化学位移基本保持不变. 相似文献
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用INDO系列方法研究C78(CH2)2的18种可能异构体,表明最稳定异构体是42,43,62,63-C78(CH2)2,其中CH2加在C78(C2V)椭球长轴所穿过的同一六员环的两个6/6键上,形成类环丙烷结构。并对最稳定的四种异构体用B3LYP/3-21G方法进行了结构优化,在此基础上, 用INDO/CIS方法计算的C78(CH2)2稳定异构体的电子光谱的第一吸收峰和用AM1方法计算的碳笼上的C-C键的主要红外振动频率与C78(C2V)相比发生兰移,原因是C78(CH2)2具有较大的LUMO-HOMO能隙和由于加成带来的共轭体系变小。在B3LYP/3-21G水平上计算的13C NMR谱表明,被加成的C-C键上的C原子化学位移向高场移动, 这是因为sp2杂化的C 原子被转化为 sp3杂化的C 原子. 相似文献
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