Molecular Recognition of Alkylammonium Contact Ion-Pairs Using a Ditopic Receptor

A ditopic, macrobicyclic receptor with adjacent
anion and cation binding sites is able to distinguish between
various monoalkylammonium salts by binding them as
contact ion-pairs. The affinity for linear n-propylammonium
chloride is at least 2 orders of magnitude greater than that
for n-propylammonium acetate, n-propylammonium p-toluenesulfonate, and branched isopropylammonium chloride.
An X-ray structure of the receptor complexed with methylammonium chloride illuminates the basis of the molecular
recognition.

一种带有相邻阴离子与阳离子结合位点的双位点大环双环受体，可通过以接触离子对形式结合的方式，区分多种单烷基铵盐。该受体对直链正丙基氯化铵的结合亲和力，至少比其对正丙基乙酸铵、正丙基对甲苯磺酸盐以及支链异丙基氯化铵的结合亲和力高出两个数量级。通过解析该受体与甲基氯化铵形成复合物的X射线晶体结构，阐明了其分子识别的结构基础。