Flüssigkristalline Verbindungen, 79[1a]. Amphiphile und mesogene Kohlenhydrate, V[1b]. Amphiphile Fluorglucose‐ und Fluorscyllitol‐Derivate

Abstract

Liquid Crystalline Compounds, 79[1a].–Amphiphilic and Mesogenic Carbohydrates, V[1b].–Amphiphilic Fluoroglucose and Fluoroscyllitol DerivativesIn order to look at the influence of the OH‐F substitution in the cyclic, hydrophilic section (head group) of amphiphilic sugars and of scyllitol derivatives on their liquid crystalline properties for the first time, we synthesized various differently structured fluoro‐D‐glucose derivatives [2‐O‐decyl‐α‐D‐glucopyranosyl fluoride (4), 4‐O‐tetradecyl‐α‐D‐glucopyranosyl fluoride (5), 6‐O‐hexadecyl‐α‐D‐glucopyranosyl fluoride (6), 6‐deoxy‐6‐fluoro‐2,3‐di‐O‐hexadecyl‐D‐glucopyranose (9), 2‐deoxy‐2‐fluoro‐4,6‐O‐alkyliden‐D‐glucopyranosen (11a–d), 3‐deoxy‐3‐fluoro‐5,6‐di‐O‐tetradecyl‐D‐glucofuranose (15)] as well as the 2‐deoxy‐2‐fluoro‐2,3,4,5,6‐tetra‐O‐hexyl‐scyllo‐in‐osit (19). Substitution of an OH group for a fluorine atom in amphiphilic derivatives destabilizes the thermotropic mesophase as it was to be expected so that either no or only narrowrange mesophases result. Both thermotropic and lyotropic liquid crystal phases occur in the series of 2‐deoxy‐2‐fluoro‐D‐glucopyranose acetals 11 which are discussed in detail and which are compared with the analogous 2‐hydroxy derivatives 12. Only 11c–d are thermotropic fluoro mesogens.