Evidence of a polar cybotactic smectic A phase in a new fluorine substituted bent-core compound

Nagaraj, Mamatha; Lehmann, Anne; Prehm, Marko; Tschierske, Carsten; Vij, J. K.

doi:10.1039/c1jm13140k

Cited by 22 publications

(6 citation statements)

References 29 publications

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“…2 ) as would be expected for a transition to a SmA phase, and hence this phase is tentatively assigned as CybA. Related tilted [ 69 ] and nontilted phases [ 79 ] with structures intermediate between the N cyb phases and undistorted smectic phases have been observed previously and seem to represent a typical phenomenon for molecules at the borderline between a bent-core and rod-like shape.…”

Section: Resultssupporting

confidence: 65%

Liquid-crystalline heterodimesogens and ABA-heterotrimesogens comprising a bent 3,5-diphenyl-1,2,4-oxadiazole central unit

Shanker¹,

Prehm²,

Tschierske³

2012

Beilstein J. Org. Chem.

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SummaryThree new types of terminally connected ABA-heterotrimesogens and heterodimesogens, composed of a bent 3,5-diphenyl-1,2,4-oxadiazole central unit and one or two rod-shaped 4-cyanobiphenyl cores or one 2-phenyl-1,3,4-thiadiazole core, connected by flexible spacers, have been synthesized, and their mesomorphic behavior was studied by optical polarizing microscopy (PM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). All dimesogens exhibit broad ranges of cybotactic nematic phases (NcybA and NcybC), in some cases accompanied by additional mesophases (CybA or SmC) at lower temperature. The combination of the 3,5-diphenyl-1,2,4-oxadiazole unit with one cyanobiphenyl core leads to the removal of tilted smectic and cybotactic nematic phases (SmC, NcybC), which are replaced by the nontilted CybA phases and nematic phases composed of SmA-type clusters (NcybA). The orthogonal cybotactic nematic phases of bent-core mesogens are of special interest for achieving biaxial nematic phases of the orthorhombic type. The orthogonal (NcybA) and skewed (NcybC) cybotactic nematic phases were distinguished by XRD and optical observations.

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Section: Resultssupporting

confidence: 65%

Liquid-crystalline heterodimesogens and ABA-heterotrimesogens comprising a bent 3,5-diphenyl-1,2,4-oxadiazole central unit

Shanker¹,

Prehm²,

Tschierske³

2012

Beilstein J. Org. Chem.

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“…Pre‐transitional effects [72–80] have been known for several years. Litster and Stinson [81] investigated nematic LCs by means of light scattering experiments and observed increased scattering intensities a few Kelvin before the phase transition from the isotropic to the nematic phase.…”

Section: Ilc Mesomorphismmentioning

confidence: 99%

Current Topics in Ionic Liquid Crystals

et al. 2021

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Ionic liquid crystals (ILCs), that is, ionic liquids exhibiting mesomorphism, liquid crystalline phases, and anisotropic properties, have received intense attention in the past years. Among others, this is due to their special properties arising from the combination of properties stemming from ionic liquids and from liquid crystalline arrangements. Besides interesting fundamental aspects, ILCs have been claimed to have tremendous application potential that again arises from the combination of properties and architectures that are not accessible otherwise, or at least not accessible easily by other strategies. The current review highlights recent developments in ILC research, starting with some key fundamental aspects. Further subjects covered include the synthesis and variations of modern ILCs, including the specific tuning of their mesomorphic behavior. The review concludes with reflections on some applications that may be within reach for ILCs and finally highlights a few key challenges that must be overcome prior and during true commercialization of ILCs.

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“…Among the organic materials, thermotropic ILCs are considered appealing for their peculiar combination of low volatility, good solvent capability and their good ionic conductivity of ionic liquids (ILs) with the anisotropy of liquid crystals (LCs) that is typical for intrinsically ordered media [1,2]. These combined properties allow ILCs to be exploited in a variety of fields, such as acting as electrolytes for batteries, [3] in dye-sensitized solar cells, [4] in sensors, [5,6] and as water desalination membranes, [7] to cite a few. Aside from the widely explored cationic cores such as imidazolium and pyridinium, [8][9][10] other heterocyclic core ionic structures, such as oxadiazoles and triazoles, which have been mainly investigated for their biological activity, [11][12][13][14] are interesting for their predictable tuning of mesophase behavior [1,15] when segregations between polar charged regions and non-polar aliphatic chains are expected to drive self-assembly.…”

Section: Introductionmentioning

confidence: 99%

Shaping 1,2,4-Triazolium Fluorinated Ionic Liquid Crystals

et al. 2023

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The synthesis and thermotropic behaviour of some di-alkyloxy-phenyl-1,2,4-triazolium trifluoromethane-sulfonate salts bearing a seven-carbon atom perfluoroalkyl chain on the cation is herein described. The fluorinated salts presenting a 1,2,4-triazole as a core and differing in the length of two alkyloxy chains on the phenyl ring demonstrated a typical liquid crystalline behaviour. The mesomorphic properties of this set of salts were studied by differential scanning calorimetry and polarized optical microscopy. The thermotropic properties are discussed on the grounds of the tuneable structures of the salts. The results showed the existence of a monotropic, columnar, liquid crystalline phase for the salts tested. An increase in the temperature mesophase range and the presence of two enantiotropic mesophases for the sixteen-atom alkyloxy chain salt can be observed by increasing the length of the alkyloxy chain on the phenyl ring.

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Evidence of a polar cybotactic smectic A phase in a new fluorine substituted bent-core compound

Cited by 22 publications

References 29 publications

Liquid-crystalline heterodimesogens and ABA-heterotrimesogens comprising a bent 3,5-diphenyl-1,2,4-oxadiazole central unit

Liquid-crystalline heterodimesogens and ABA-heterotrimesogens comprising a bent 3,5-diphenyl-1,2,4-oxadiazole central unit

Current Topics in Ionic Liquid Crystals

Shaping 1,2,4-Triazolium Fluorinated Ionic Liquid Crystals

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