Fluorocarbon and Hydrocarbon N-Heterocyclic (C5-C7) Imidazole-Based Liquid Crystals

• Published in: Chemistry, an Asian journal Vol. 9; no. 12; pp. 3418 - 3430
• Main Authors: Chen, Hongren, Hong, Fengying, Shao, Guang, Hang, Deyu, Zhao, Lei, Zeng, Zhuo
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.12.2014; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: Chemistry; Crystals; fluorine; heterocycles; ionic liquids; Ions; mesophases; Perfluorocarbons; phase transitions; X-rays; mesophases; phase transitions; ionic liquids; heterocycles; fluorine
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.201402576

By using three synthetic protocols, a series of fluorocarbon and hydrocarbon N‐heterocyclic imidazole‐based liquid crystals (LCs) and related imidazolium‐based ionic liquid crystals (ILCs) have been prepared. The ring size of the N‐heterocycle and the length of the N‐terminal chain (on the imidazolium unit in the ILCs) were modified, and the influence of these structural parameters on liquid‐crystal phases was investigated by means of polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and X‐ray diffraction (XRD). These new ILCs exhibit a disordered smectic phase (SmA), good thermal stabilities, a broad smectic phase range, a high dipole moment, relatively low melting points, but high clearing points and strong emission fluorescence relative to imidazole‐based LCs. These encouraging results have led us to believe these fluorocarbon and hydrocarbon N‐heterocyclic imidazole‐based LCs and related imidazolium‐based ILCs could be used as new liquid‐crystalline materials. Crystal clear: A series of fluorocarbon and hydrocarbon N‐heterocyclic imidazole‐based liquid crystals and related imidazolium‐based ionic liquid crystals have been prepared. They exhibit good thermal stabilities, a broad smectic phase range, a high dipole moment, relatively low melting points, but high clearing points and strong emission fluorescence, which could make them suitable for use as new liquid‐crystal materials (see figure).