Substituent Effects in Parallel-Displaced π-π Stacking Interactions: Distance Matters
作者:Leslie-Joana Riwar、Nils Trapp、Bernd Kuhn、François Diederich
DOI:10.1002/anie.201703744
日期:2017.9.4
Host–guest systems with Rebek imide type receptors and a 2,6‐di(isobutyramido)pyridine ligand were employed to investigate substituent effects in parallel‐displaced π–π stacking interactions. Changing the intermolecular distance between the para substituent on the aromatic platform of the receptor and the pyridine ring of the guest results in a strongly different substituent effect. With a short ethyne‐1
具有Rebek酰亚胺类型受体和2,6-二(异丁酰胺基)吡啶配体的宿主-客体系统用于研究平行位移π-π堆积相互作用中的取代基效应。改变的分子间距离对 受体的芳族平台上的取代基和客体的吡啶环导致强烈的取代基效应。在Rebek酰亚胺和芳族平台之间有一个较短的乙炔-1,2-二烷基间隔基,取代基和客体的部分重叠可稳定π-π堆积相互作用,而与取代基的电子性质无关(Wheeler-Houk模型)。当使用buta-1,3-diyne-1,4-diyl间隔基将取代基进一步移开时,可防止取代基与客体之间的直接,空间相互作用。线性的logK之间的相关一个(K一=缔合常数)和Hammett取代基常数σ对位是观察,确认由所述亨特-桑德斯模型实验预测。