Self-fulfilling cavitands: Packing alkyl chains into small spaces
Self-fulfilling cavitands: Packing alkyl chains into small spaces
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DOI：
10.1073/pnas.0511149103
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发表时间：
2006-02-21
影响因子：
11.1
通讯作者：
Rebek, J
中科院分区：
文献类型：
--
作者：
Purse, BW;Rebek, J
目前的研究进行，以确定构象的烷基被迫进入小空间。无支链的烷基在溶液的自由空间中呈现完全伸展的构象，因为结构中的任何弯曲都会在链上沿着的氢之间产生空间冲突。我们合成了一系列的羧酸烷基酯附着在花瓶状容器结构的内表面。较短的酯（乙基和丙基）可以容纳在扩展的构象，甚至小的溶剂分子可以共享容器的空间。较长的（丁基-辛基）酯采用越来越多的卷曲构象，在有限的空腔空间内迅速扭动。甚至更长的酯（壬基和癸基）可以合成，但它们的容器变得扭曲，它们的光谱表明烷基在空间内的内部运动减慢。一般来说，当烷基的内部张力通过与内表面的吸引和空间的适当填充而得到补偿时，烷基容易扭曲。
The present research was undertaken to determine the conformations of alkyl groups that are forced into small spaces. Unbranched alkyl groups assume fully extended conformations in the free space of solutions, because any bends in the structure create steric clashes between hydrogens along the chain. We synthesized a series of alkyl esters of a carboxylic acid attached to the inner surface of a vase-shaped container structure. The shorter esters (ethyl and propyl) can be accommodated in extended conformations, and even small solvent molecules can share the container's space. Longer (butyl-octyl) esters adopt increasingly coiled conformations that writhe rapidly in the limited space of the cavity. Even longer esters (nonyl and decyl) can be synthesized, but their containers become distorted, and their spectra indicate slowed internal motions of the alkyl groups within the space. In general, alkyl groups are readily contorted when their internal strains are compensated by attraction with the inner surfaces and the proper filling of space.