Helical folding of alkanes in a self-assembled, cylindrical capsule
Helical folding of alkanes in a self-assembled, cylindrical capsule
复制标题
DOI：
10.1021/ja047952f
复制
发表时间：
2004-10-20
影响因子：
15
通讯作者：
Rebek, J
中科院分区：
文献类型：
--
作者：
Scarso, A;Trembleau, L;Rebek, J
用核磁共振方法研究了一系列正构烷烃客体在圆柱形主体中的可逆包封。对于小的碳氢化合物，如正戊烷或正己烷，两个客人进入主机，他们在内部自由移动。对于正庚烷，不发生包封。对于较长的烷烃，如正癸烷，单个客体进入，并且主体的芳族壁被视为扭曲以避免空的空间并增加与烃的有利相互作用。最好的客体（正十一烷）采用最小的笨拙相互作用的构象。最长的烷烃，正十四烷，采用螺旋构象，以适应在空腔中，一个形状，最大限度地提高CH/π与受体的芳香壁的相互作用。这些互惠构象变化进行了讨论，在最佳的主机/客人的相互作用。
The reversible encapsulation of a series of normal alkane guests in a cylindrical host was studied by NMR methods. For small hydrocarbons such as n-pentane or n-hexane, two guests enter the host, and they move freely within. With n-heptane no encapsulation takes place. For longer alkanes such as n-decane, a single guest enters and the aromatic walls of the host are seen to twist to avoid empty spaces and increase favorable interactions with the hydrocarbon. The best guest (n-undecane) adopts a conformation with minimal gauche interactions. The longest alkane accommodated, n-tetradecane, adopts a helical conformation to fit in the cavity, a shape that maximizes CH/pi interactions with the aromatic walls of the receptor. These reciprocal conformational changes are discussed in terms of optimal host/guest interactions.