Popov Alexey A, Kareev Ivan E, Shustova Natalia B, Lebedkin Sergey F, Strauss Steven H, Boltalina Olga V, Dunsch Lothar
Chemistry Department, Moscow State University, Moscow 119992, Russia.
Chemistry. 2008;14(1):107-21. doi: 10.1002/chem.200700970.
Eight new C70(CF3)n derivatives (n=2, 6, 10, 12) have been synthesized and characterized by UV/Vis and 19F NMR spectroscopy, cyclic voltammetry, and quantum chemical calculations at the DFT level of theory. Nine previously known derivatives of C70(CF3)n with n=2-12 were also studied by cyclic voltammetry (and seven of them by UV/Vis spectroscopy for the first time). Most of the 17 compounds exhibited two or three reversible reductions at scan rates from 20 mV s(-1) up to 5.0 V s(-1). In general, reduction potentials for the 0/- couple are shifted anodically relative to the C70 0/-) couple. However, the 0/- E1/2 values for a given composition are strongly dependent on the addition pattern of the CF3 groups. The data show that the addition pattern is as important, if not more important in some cases, than the number of substituents, n, in determining E1/2 values. An analysis of the DFT-predicted LUMOs indicates that addition patterns that have non-terminal double bonds in pentagons result in derivatives that are strong electron acceptors.
已合成了八种新的C70(CF3)n衍生物（n = 2、6、10、12），并通过紫外可见光谱和19F核磁共振光谱、循环伏安法以及在密度泛函理论（DFT）水平上的量子化学计算对其进行了表征。还通过循环伏安法研究了九种先前已知的n = 2 - 12的C70(CF3)n衍生物（其中七种首次通过紫外可见光谱进行了研究）。在扫描速率从20 mV s(-1)到5.0 V s(-1)的范围内，这17种化合物中的大多数都表现出两到三次可逆还原。一般来说，相对于C70的0/-) 偶合，0/- 偶合的还原电位向阳极方向移动。然而，给定组成的0/- E1/2值强烈依赖于CF3基团的添加模式。数据表明，在确定E1/2值时，添加模式即使在某些情况下不更重要，也是同样重要的，与取代基数n相当。对DFT预测的最低未占分子轨道（LUMO）的分析表明，在五边形中具有非末端双键的添加模式会导致衍生物成为强电子受体。
