Counterion Effects on the Mesomorphic Properties of Chiral Imidazolium and Pyridinium Ionic Liquids

Novel calamitic N‐methylimidazolium and pyridinium salts with modified citronellyl side‐chains and various counterions 3–14 have been synthesised by utilising the commercially available (R)‐citronellol (15) as the starting material. Differential scanning calorimetry (DSC), polarising optical microscopy (POM) and temperature‐dependent X‐ray diffraction studies revealed smectic A (SmA) mesophases for all the series. 1H NMR studies of the N‐methylimidazolium salts have shown that there is a correlation between the mesophase dependence on the counterion and the counterion‐dependent chemical shifts of the acidic 2‐H proton.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) N‐Methylimidazolium and pyridinium salts with modified citronellyl side‐chains and various counterions have been synthesised by using the commercially available (R)‐citronellol as the starting material and their mesomorphic properties investigated.