Kang J, Rebek J
Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139, USA.
Nature. 1997 Jan 2;385(6611):50-2. doi: 10.1038/385050a0.
The interior of cage-like molecules can be considered to provide a new phase of matter, in which it becomes possible to stabilize reactive intermediates and to observe new forms of stereoisomerism. Cage-like molecular complexes that self-assemble through weak intermolecular forces are dynamic species, encapsulating guest molecules reversibly. They can persist over timescales ranging from microseconds to hours, long enough for chemical processes to take place within them. Here we report the acceleration of a Diels-Alder reaction by encapsulation of the reactants in a self-assembling molecular capsule. Although product inhibition (lack of dissociation) prevents the system from showing true catalytic behaviour, there is clear evidence for a rate increase of over two orders of magnitude owing to the effective enhancement of concentration inside the capsule.
笼状分子的内部可被视为提供了一种新的物质相态，在其中能够稳定反应中间体并观察到新形式的立体异构现象。通过弱分子间作用力自组装而成的笼状分子复合物是动态物种，能可逆地包封客体分子。它们可以在从微秒到小时的时间尺度上持续存在，长到足以让化学过程在其中发生。在此，我们报道了通过将反应物包封在自组装分子胶囊中加速狄尔斯-阿尔德反应。尽管产物抑制（解离不足）使该体系无法表现出真正的催化行为，但有明确证据表明，由于胶囊内部浓度的有效提高，反应速率提高了两个数量级以上。
