Departamento de Química Física, Facultade de Química, Universidade de Santiago de Compostela, Lugo, Spain.
J Phys Chem B. 2011 Mar 31;115(12):2774-82. doi: 10.1021/jp109654e. Epub 2011 Mar 8.
A systematic study of the interaction of alkaline cations with curved π systems (molecular bowls) derived from fullerene (C(60)) shows the ability of these structures to form stable cation-π complexes with both of their sides: concave and convex. In all cases, complexes with the cation in the convex side are more stable than its corresponding partner inside the bowl. When forming the complexes with the alkaline cations, these bowls exhibit great stability but several descriptors that usually work in planar conjugate molecules (like the magnitude of the charge transferred to the cation or the cation-ligand distance) do not properly describe the trends observed. The present study shows that with these curved π systems inductive effects play a central role in the formation of complexes with alkaline cations. This conclusion contradicts the simplistic point of view on the dominant effect of the electrostatic term in the interaction between alkaline cations and bowls derived from fullerene. Additionally, steric effects can be relevant when bulky cations are placed in the concave side of the largest bowls.
对富勒烯（C(60)）衍生的弯曲π体系（分子碗）与碱性阳离子相互作用的系统研究表明，这些结构能够与两侧（凹面和凸面）形成稳定的阳离子-π 配合物。在所有情况下，位于凸面的阳离子配合物比其在碗内的对应物更稳定。当与碱性阳离子形成配合物时，这些碗状结构表现出很高的稳定性，但通常在平面共轭分子中起作用的几个描述符（如转移到阳离子的电荷量或阳离子-配体距离）不能很好地描述观察到的趋势。本研究表明，对于这些弯曲的π体系，诱导效应在与富勒烯衍生的碱性阳离子形成配合物中起着核心作用。这一结论与碱性阳离子与富勒烯衍生的碗之间相互作用中静电项起主导作用的简单观点相矛盾。此外，当将大体积阳离子置于最大碗的凹面时，空间位阻效应可能会相关。
