Ionic Self Assembly in the Design of Fluorinated Ionic Liquid Crystals (ILCs)

Abstract

Ionic liquid crystals are a class of compounds containing anions and cations, that combine the properties of liquid crystals and ionic liquids[1]. In the conventional design of ionic liquid crystalline compounds, an ionic core is connected with mesogenic groups via chemical covalent bonding . Alternatively, in ionic compounds, strong electrostatic interactions between cation and anion can be used to build up liquid crystalline order at supramolecular level. This general approach, called ionic self-assembly (ISA), allows one to create ionic phases and mesophases with highly organized supramolecular order [2]. In this context, a new series of fluorinated ionic liquids (ILs) and ionic liquid crystals (ILCs) was obtained starting from perfluoro-alkylated carboxylic acids and 1,2,4-oxadiazolyl-pyridine units (Figure 1). Their thermotropic properties were investigated by combined differential scanning calorimetry and polarized optical microscopy. Figure 1. [1] K.V. Axenov and S. Laschat, Materials, 4, 2011, 206; F. Lo Celso, I. Pibiri, A. Triolo, R. Triolo, A. Pace, S. Buscemi and N. Vivona, J. Mater. Chem., 17, 2007, 1201; V. Causin and G. Saielli, J. Mater. Chem., 19, 2009, 9153. [2] C.F.J. Faul and M. Antonietti, Adv. Mater., 15, 2003, 673.