6533b7d8fe1ef96bd126a394
RESEARCH PRODUCT
Ionic liquid crystals based on viologen dimers: tuning the mesomorphism by varying the conformational freedom of the ionic layer
Federico RastrelliGirolamo CasellaGiacomo SaielliValerio Causinsubject
4-4?-bipyridinium4-4ʹ-bipyridiniumMaterials scienceIonic liquid crystals; viologens; 4-4ʹ-bipyridiniumIonic bonding02 engineering and technology010402 general chemistry01 natural scienceschemistry.chemical_compoundLiquid crystalPhase (matter)medicineOrganic chemistryGeneral Materials ScienceBistriflimideviologensAlkylSettore CHIM/02 - Chimica Fisicachemistry.chemical_classificationviologenChemistry (all)MesophaseViologenGeneral ChemistrySettore CHIM/06 - Chimica Organica4-4ʹ-bipyridinium; Ionic liquid crystals; viologens; Condensed Matter Physics; Materials Science (all); Chemistry (all)021001 nanoscience & nanotechnologyCondensed Matter Physics0104 chemical sciencesCrystallographychemistryIonic liquidIonic liquid crystalsIonic liquid crystalMaterials Science (all)0210 nano-technologymedicine.drugdescription
ABSTRACTWe investigated the liquid crystal behaviour of newly synthesised bistriflimide salts of symmetric viologen dimers. A smectic A phase was observed for intermediate spacer lengths and for relatively long lateral alkyl chains. The systems were characterised by thermal analysis, polarised optical microscopy, X-ray scattering and solid-state NMR. An intermediate ordered smectic phase was also exhibited by the compounds (except for systems with very short lateral chains) consisting of molten layers of alkyl chains and partially ordered ionic layers. These results, relating to the mesomorphic behaviour of viologen salts, are qualitatively compared to those of the more common imidazolium salts, highlighting the importance of the conformational degrees of freedom of the anions and of the cationic core. It appears that fine tuning of the conformational degrees of freedom of the ionic layer is an important component of mesophase stabilisation.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2016-03-30 |