Synthesis of Novel Chiral Ionic Liquids and Their Phase Behavior in Mixtures with Smectic and Nematic Liquid Crystals

✍ Scribed by Martin Tosoni; Sabine Laschat; Angelika Baro

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: German
• Weight: 197 KB
• Volume: 87
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.200490247

✦ Synopsis

Abstract

Alkylation of 1‐alkyl‐1__H__‐imidazoles 2a–f with citronellyl bromide 1b opens access to chiral 1__H__‐imidazolium bromides 3a–f (Scheme 1). A similar strategy yielded the chiral pyridinium ionic liquid 6 (Scheme 2). Dialkylation of 1__H__‐imidazole (7) gave the C~2~‐symmetric 1,3‐dicitronellyl‐1__H__‐imidazolium bromide (8) (Scheme 3). Differential scanning calorimetry and optical polarizing microscopy revealed smectic mesophases for 1‐citronellyl‐3‐tetradecy‐1__H__‐limidazolium bromide (3e) and 1‐citronellylpyridinium bromide (6) (Table). In binary mixtures with smectic and nematic liquid crystals 9 and 10, 1‐citronellyl‐3‐methyl‐1__H__‐imidazolium bromide (3a) behaved differently. Increasing quantities of 3a cause a decrease of the smectic‐phase width for the mixture 3a/9 (Fig. 3), whereas the phase width of the nematic phase for 3a/10 remained nearly constant (Fig. 4).