On the Orientation of Small Molecules in Anisotropic Solvents
On the Orientation of Small Molecules in Anisotropic Solvents
复制标题
各向异性溶剂中小分子的取向
DOI：
10.1007/978-94-009-6517-1_8
复制
发表时间：
1985
期刊：
影响因子：
--
通讯作者：
E. Burnell
中科院分区：
文献类型：
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作者：
C. A. D. Lange;J. G. Snijders;E. Burnell
虽然描述各向异性环境中刚性分子的取向是一个直截了当的问题，但要完全令人满意地解释内部运动的影响并不那么容易。对于具有大振幅分子内运动的溶质，如何处理其平均取向问题引起了一些争议。第一次尝试用动力学方法来描述问题，其中内部运动和重新定向的相关时间尺度的比例起着重要作用（1,2），随后是使用平衡统计力学的看似替代的描述(3)。在后来的一篇论文中，证明了一个更一般的理论包含了这两种方法作为特殊情况，从而证明了它们的本质等价(4)。这些理论至少导致了对如何解释分子内运动的定性理解。尽管做出了这些努力，但仍然缺乏对显示小各向异性耦合和只有小振幅内部振动的小分子的详细描述。一个恰当的例子是在其平衡构象中具有四面体或更高对称性的分子。
Although the description of the orientation of rigid molecules in an anisotropic environment is a straightforward problem, it has not been quite so easy to account for the effects of internal motion completely satisfactorily. For solutes with large-amplitude intramolecular motions the problem of how to treat their average orientation has given rise to some controversy. A first attempt to phrase the problem in terms of a kinetic approach in which the ratio of the relevant time scales for internal motion and reorientation plays an important role (1,2) was followed by a seemingly alternative description using equilibrium statistical mechanics (3). In a later paper it was shown that a more general theory encompassed both these approaches as special cases, hence demonstrating their essential equivalence (4). Such theories have led to at least a qualitative understanding of how to account for intramolecular motions. Despite these efforts, a detailed description of even small molecules showing small anisotropic couplings and with only small-amplitude internal vibrations is still lacking. A case in point are molecules which in their equilibrium conformation possess tetrahedral or higher symmetry.