scholarly journals Influence of alkyl chain length and fluorine atoms substitution on infrared spectra of chiral liquid crystalline esters

2017 ◽  
Vol 66 (3) ◽  
pp. 63-74
Author(s):  
Anna Drzewicz ◽  
Marzena Tykarska ◽  
Magdalena Żurowska
Keyword(s):  
Molecular Structure ◽  
Infrared Spectroscopy ◽  
Liquid Crystals ◽  
Infrared Spectra ◽  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Alkyl Chain ◽  
Alkyl Chain Length ◽  
Rigid Core ◽  
Helicoidal Structure

The infrared spectra were registered for series of three-ring liquid crystalline esters, differing in the structure of alkyl chain, in the substitution of benzene ring by fluorine atoms and in the type of helicoidal structure in the chiral smectic CA phase with antiferroelectric properties. The influence of molecular structure on the shift of signals coming from carbonyl group, located in the rigid core, was observed. Keywords: liquid crystals, helicoidal structure, chiral smectic CA phase, antiferroelectric crystalline phase, infrared spectroscopy

scholarly journals Influence of molecular structure on helicoidal structure and NMR spectra of chiral liquid crystalline esters

2017 ◽  
Vol 66 (2) ◽  
pp. 25-35
Author(s):  
Anna Drzewicz ◽  
Marzena Tykarska ◽  
Mateusz Szala ◽  
Magdalena Żurowska
Keyword(s):  
Molecular Structure ◽  
Nmr Spectra ◽  
Liquid Crystalline ◽  
Room Temperature ◽  
Alkyl Chain ◽  
Light Reflection ◽  
13C Nmr Spectra ◽  
1H And 13C Nmr ◽  
Antiferroelectric Phase ◽  
Helicoidal Structure

Three-ring chiral liquid crystalline compounds, forming antiferroelectric phase, differing in the structure of alkyl chain and in the substitution of benzene ring by fluorine atoms were studied. The measurements of helical pitch, based on the selective light reflection phenomenon, were performed as well as 1H and 13C NMR spectra at room temperature were registered. The influence of molecular structure as well as the type of helicoidal structure on the chemical shift of signals coming from chiral center was observed. Keywords: liquid crystals, helicoidal structure, nuclear magnetic resonance, antiferroelectric phase

scholarly journals Dielectric Properties of Chiral Ferroelectric Liquid Crystalline Compounds with Three Aromatic Rings Connected by Ester Groups

Crystals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 473 ◽  
Author(s):  
Malay Kumar Das ◽  
Barnali Barman ◽  
Banani Das ◽  
Věra Hamplová ◽  
Alexey Bubnov
Keyword(s):  
Molecular Structure ◽  
Phase Transition ◽  
Liquid Crystalline ◽  
Alkyl Chain ◽  
Dielectric Strength ◽  
Relaxation Frequency ◽  
Goldstone Mode ◽  
Aromatic Rings ◽  
Structural Variations ◽  
Polar Order

The tilted ferroelectric SmC* phase of three structurally different series having three aromatic rings in the core structure connected by ester groups with different end alkyl chain lengths, all of which are derived from lactic acid, have been observed by broadband dielectric spectroscopy. Introduction of structural variations within the liquid crystalline compounds has led to the formation of chiral nematic N*, or the paraelectric orthogonal SmA* phase at higher temperatures. The dielectric spectra strongly depend both on the temperature as well as the specific molecular structure of the self-assembling compounds possessing the ferroelectric polar order. The results reveal a strong Goldstone mode in the ferroelectric SmC* phase with ~kHz relaxation frequency. In the SmC* phase, the real and imaginary parts of the complex permittivity increase up to certain temperature near the SmC*-N*/SmA* transition and then decrease with increasing temperature, perhaps due to the disruption of the molecular domains at the onset of the SmA*/N* phase transition. The dielectric strength attains a maximum value in the SmC* phase and then decreases near the SmA*/N* phase transition. The dielectric strength is also influenced by the lengths of the alkyl chain and the nature of the connecting unit of the constituent molecules. The relaxation time and the relaxation frequency are found to vary with the molecular structure of the studied ferroelectric compounds.

Synthesis and Mesomorphic Properties of New Liquid Crystalline Cyclohexyl-phenyl- and Dicyclohexyl-pyrimidines

1979 ◽  
Vol 34 (11) ◽  
pp. 1535-1541 ◽  
Author(s):  
Alois Villiger ◽  
Arthur Boiler ◽  
Martin Schadt
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Alkyl Chain ◽  
Viscosity Reduction ◽  
Refractive Indices ◽  
Thermal Compatibility ◽  
Chain Lengths ◽  
New Compounds ◽  
Mesomorphic Properties ◽  
End Group

Abstract Liquid Crystals, Cyclohexyl-phenyl-pyrimidines, Dicyclohexyl-pyrimidines The synthesis and mesomorphic properties of three new classes of cyano-substituted cyclohexyl-phenyl-and dicyclohexyl-pyrimidines are reported. The compounds are colourless, chemically and photochemically stable and have wide nematic mesophases. The thermal compatibility of the new compounds with other nematic liquid crystals is excellent. The large static positive dielectric anisotropics are shown to depend strongly on the position and number of hydrogenated rings as well as on the alkyl chain lengths within a homologous series. The reported bulk viscosities vary considerably among homologues. Hydrogenating the ring adjacent to the cyano end group causes η to increase, whereas a considerable viscosity reduction compared to nonhydrogenated homologues was found by hydrogenating the ring adjacent to the alkyl end group. The measured refractive indices of the new compounds are comparable to those of biphenyls.

scholarly journals Design of Ionic Liquid Crystals Forming Normal-Type Bicontinuous Cubic Phases with a 3D Continuous Ion Conductive Pathway

Crystals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 309 ◽  
Author(s):  
Takahiro Ichikawa ◽  
Yui Sasaki ◽  
Tsubasa Kobayashi ◽  
Hikaru Oshiro ◽  
Ayaka Ono ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Liquid Crystals ◽  
Ionic Conductivity ◽  
Liquid Crystalline ◽  
Alkyl Chain ◽  
Normal Type ◽  
Ion Conduction ◽  
Cubic Phases ◽  
Bicontinuous Cubic ◽  
Chain Lengths

We have prepared a series of pyridinium-based gemini amphiphiles. They exhibit thermotropic liquid–crystalline behavior depending on their alkyl chain lengths and anion species. By adjusting the alkyl chain lengths and selecting suitable anions, we have obtained an ionic amphiphile that exhibits a normal-type bicontinuous cubic phase from 38 °C to 12 °C on cooling from an isotropic phase. In the bicontinuous cubic liquid–crystalline assembly, the pyridinium-based ionic parts align along a gyroid minimal surface forming a 3D continuous ionic domain while their ionophobic alkyl chains form 3D branched nanochannel networks. This ionic compound can form homogeneous mixtures with a lithium salt and the resultant mixtures keep the ability to form normal-type bicontinuous cubic phases. Ion conduction measurements have been performed for the mixtures on cooling. It has been revealed that the formation of the 3D branched ionophobic nanochannels does not disturb the ion conduction behavior in the ionic domain while it results in the conversion of the state of the mixtures from fluidic liquids to quasi-solids, namely highly viscous liquid crystals. Although the ionic conductivity of the mixtures is in the order of 10–7 S cm–1 at 40 °C, which is far lower than the values for practical use, the present material design has a potential to pave the way for developing advanced solid electrolytes consisting of two task-specific nanosegregated domains: One is an ionic liquid nano-domain with a 3D continuity for high ionic conductivity and the other is ionophobic nanochannel network domains for high mechanical strength.

Pyridinium salt liquid crystals Effect of mesogen extension and alkyl chain length

1995 ◽  
Vol 18 (3) ◽  
pp. 475-482 ◽  
Author(s):  
Maryam Tabrizian ◽  
Armand Soldera ◽  
Michel Couturier ◽  
C. Geraldine Bazuin
Keyword(s):  
Liquid Crystals ◽  
Chain Length ◽  
Alkyl Chain ◽  
Pyridinium Salt ◽  
Alkyl Chain Length

THE EFFECT OF THE ALKYL CHAIN LENGTH ON THE LIQUID CRYSTALLINE PROPERTIES OF P-SUBSTITUTED CHOLESTERYL 4-BENZOYLBENZOATES

1981 ◽  
Vol 10 (2) ◽  
pp. 269-272 ◽  
Author(s):  
Mitsuhiro Koden ◽  
Tadao Yagyu ◽  
Shunsuke Takenaka ◽  
Hikaru Terauchi ◽  
Shigekazu Kusabayashi
Keyword(s):  
Chain Length ◽  
Liquid Crystalline ◽  
Alkyl Chain ◽  
Alkyl Chain Length

Multifunctional Materials via Molecular Self-Organization into Liquid-Crystalline Phase

2008 ◽  
Vol 47-50 ◽  
pp. 165-168 ◽  
Author(s):  
Suk Wah Tam-Chang ◽  
Delfin Mahinay ◽  
Li Ming Huang
Keyword(s):  
Liquid Crystals ◽  
Organic Compound ◽  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Liquid Crystalline Phase ◽  
Self Organization ◽  
Local Order ◽  
Self Organized ◽  
Polymer Template ◽  
Micrometer Scale

In this paper, we described the synthesis of N,N’-di-(2-ammoniumethyl)perylene- 3,4,9,10-bis(dicarboximide) ditrifluoroacetate (1), an ionic organic compound that self-organized to give chromonic liquid crystals and anisotropic crystals. Using a polymer template with micrometer-scale features to direct the ordered arrangement of 1, patterned structure with micrometer-scale local order was fabricated. The anisotropic (direction-dependent) properties of the crystals and micropatterns of 1 were investigated.

scholarly journals Oxadiazolyl-Pyridinium as Cationic Scaffold for Fluorinated Ionic Liquid Crystals

2021 ◽  
Vol 11 (21) ◽  
pp. 10347
Author(s):  
Melina S. Weber ◽  
Margit Schulze ◽  
Giuseppe Lazzara ◽  
Antonio Palumbo Piccionello ◽  
Andrea Pace ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Alkyl Chain ◽  
Scanning Calorimetry ◽  
New Class ◽  
Structural Variables ◽  
Ionic Liquid Crystals ◽  
Thermotropic Properties

The synthesis and characterization of a new class of 1,2,4-oxadiazolylpyridinium as a cationic scaffold for fluorinated ionic liquid crystals is herein described. A series of 12 fluorinated heterocyclic salts based on a 1,2,4-oxadiazole moiety, connected through its C(5) or C(3) to an N-alkylpyridinium unit and a perfluoroheptyl chain, differing in the length of the alkyl chain and counterions, has been synthesized. As counterions iodide, bromide and bis(trifluoromethane)sulfonimide have been considered. The synthesis, structure, and liquid crystalline properties of these compounds are discussed on the basis of the tuned structural variables. The thermotropic properties of this series of salts have been investigated by differential scanning calorimetry and polarized optical microscopy. The results showed the existence of an enantiotropic mesomorphic smectic liquid crystalline phase for six bis(trifluoromethane)sulfonimide salts.

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