Separation by permeation effect in high performance liquid chromatographic studies of selected dithia[3.3]cyclophanes and thia[3.2]cyclophanenes

Abstract

The retention order of a series of conformationally mobile dithia[3.3]cyclophanes 3-7 was investigated by means of reversed-phase high performance liquid chromatography. By means of the 'slot model', the conformational behaviour of these dithiacycloplanes, which governs the extent of their interactions with the bonded phase, correlates well with the observed retention order. Another series of conformationally rigid bridge-annelated thia[3.2]cyclo-phanenes 8-14 were also similarly investigated. The anti conformation allows the whole annelated cyclophanene molecule to slide readily into the 'slot' resulting in stronger interactions between the cyclophanene and the bonded phase. The syn conformation however has the cyclophane and polycyclic benzenoid moieties held almost perpendicular so that each moiety could not possibly permeate deep into the 'slot' independently. Based on the rigid stereochemistries of 8-14, the 'slot model' again explains the observed retention order.