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Title: Mesophase stabilization in ionic liquid crystals through pairing equally shaped mesogenic cations and anions

The synthesis and properties of a set of novel ionic liquid crystals with congruently shaped cations and anions are reported to check whether pairing mesogenic cations with mesogenic anions leads to a stabilization of a liquid crystalline phase. To that avail 1-alkyl-3-methyl-triazolium cations with an alkyl chain length of 10, 12, and 14 carbon atoms have been combined with p-alkyloxy-benzenesulfonate anions with different alkyl chain lengths (n = 10, 12, and 14). The corresponding triazolium iodides have been synthesized as reference compounds where the cation and anion have strong size and shape mismatch. The mesomorphic behavior of all compounds is studied by differential scanning calorimetry and polarizing optical microscopy. All compounds except 1-methyl-3-decyltriazolium iodide, which qualifies as an ionic liquid, are thermotropic ionic liquid crystals. All other compounds adopt smectic A phases. As a result, a comparison of the thermal phase behavior of the 1-methyl-3-decyltriazolium bromides to the corresponding p-alkoxy-benzensulfonates reveals that definitely the mesophase is stabilized by pairing the rod-shaped 1-alkyl-3-methyltriazolium cation with a rod-like anion of similar size.
 [1] ;  [1] ;  [2] ;  [3] ;  [2]
  1. Ruhr-Univ. Bochum, Bochum (Germany)
  2. Ruhr-Univ. Bochum, Bochum (Germany); Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)
  3. Ruhr-Univ. Bochum, Bochum (Germany); Univ. Duisburg Essen, Essen (Germany)
Publication Date:
Report Number(s):
Journal ID: ISSN 1528-7483
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Crystal Growth and Design
Additional Journal Information:
Journal Volume: 15; Journal Issue: 11; Journal ID: ISSN 1528-7483
American Chemical Society
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
Country of Publication:
United States
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; ionic liquids; liquid crystals; ionic liquid crystals
OSTI Identifier: