features—the high affinity of squaramides toward anions, cooperation in ion pair binding and preorganization of the binding domains in the tripodal platform—led to the effective receptor 2. The lack of at least one of these key elements in the structures of reference receptors 3 and 4 caused a lower affinity towards ion pairs. Receptor 2 was found to form an intramolecular network in wet chloroform, which changed
结合三个特征——方酰胺对阴离子的高亲和力、离子对结合的配合以及三足平台中结合域的预组织——产生了有效的受体2 。参考受体3和4的结构中缺少至少一个这些关键元素导致对离子对的亲和力较低。研究发现受体2在湿
氯仿中形成分子内网络,与离子接触后转变为无机-有机缔合物,并使盐从
水相萃取到有机相。 2与
硫酸根和其他单价阴离子的结合模式的差异导致在更多亲脂盐存在下选择性提取极度
水合的
硫酸根阴离子,从而克服了霍夫迈斯特系列。