Cholesterol-based nonsymmetric liquid crystal dimers: an overview

Yelamaggad, C. V.; Shanker, Govindaswamy; Hiremath, Uma S.; Prasad, S. Krishna

doi:10.1039/b804579h

Cited by 133 publications

(79 citation statements)

References 103 publications

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“…The TGB phase showed a filament texture (Figure 3(b)) in regions where there was homeotropic alignment of the molecules, as expected. The presence of the TGB phase signifies that the ligands are strongly chiral and thus, the pitch of their N* phase is shorter; this can be attributed to the presence of cholesterol moiety (22) in ligands. It may be mentioned here that chirality is a stereochemical (symmetry) property, and thus it is qualitative.…”

Section: Liquid Crystals 251mentioning

confidence: 97%

Optically active, mesogenic lanthanide complexes: design, synthesis and characterisation

et al. 2009

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The synthesis, molecular structural characterisation and mesomorphic behaviour of lanthanidomesogens with the formula [LnL(LH) 2 ][X] 2 are reported. These mesogens were derived from ligands (LH-n) formed by covalently linking the pro-mesogenic cholesterol segment with the N-(n-decyl)salicylaldimine core through either an evenparity (4-oxybutanoyloxy/6-oxyhexanoyloxy/8-oxyoctanoyloxy) or an odd-parity (5-oxypentano-yloxy) spacer. These ligands were designed based on the recently conceived concept of decoupling the anisometric segment from the metal-coordinating site by a flexible spacer to account for the stabilisation of nematic and/or smectic phases at lower temperatures. The even parity spacer ligands are polymesomorphic whereas the odd parity analogue exhibits only the chiral nematic phase. In contrast, the complexes display solely the smectic A phase indicating that the variation in the nature of lanthanide has no influence on the general phase behaviour of the complexes. The clearing temperatures of both the ligands and the complexes display an odd-even effect; the even members show relatively higher transition temperatures.

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Section: Liquid Crystals 251mentioning

confidence: 97%

Optically active, mesogenic lanthanide complexes: design, synthesis and characterisation

et al. 2009

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“…These materials have been referred to as cholesterol based nonsymmetric liquid crystal dimers [185] and represent a new class of chiral materials that have shown a remarkable capability to generate unusual chiral phases such as blue phases (BPs) and TGB phases as well as more conventional N* phases. These materials also show similarities with the original achiral systems because the parity of the flexible spacers plays an important role in the properties of the chiral nematic phase or indeed in the generation of a smectic or chiral nematic phase.…”

Section: Type Iic and D Materials Using One Or Two Chiral Coresmentioning

confidence: 99%

Design and Synthesis of Chiral Nematic Liquid Crystals

Taugerbeck

Booth

2014

Handbook of Liquid Crystals

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The article contains sections titled: Introduction to the Chiral Nematic Phase and Its Properties Formulation and Application of Chiral Nematic Liquid Crystal Mixtures Applications of Chiral Nematic Phases Classification of Chiral Nematic Liquid‐Crystalline Compounds Aspects of Molecular Symmetry for Chiral Nematic Phases Type I Chiral Nematic Liquid Crystals Azobenzenes and Related Mesogens Azomethine ( S chiff's Base) Mesogens Stable Phenyl, Biphenyl, Terphenyl, and Phenylethylbiphenyl Mesogens Ester Mesogens Derivatives of Chiral Alcohols Type II Chiral Nematic Liquid Crystals Type IIa Twin Systems Using Chiral Flexible Spacers Type IIb Materials Using Achiral Flexible Spacers and Chiral Terminal Groups Type IIc and d Materials Using One or Two Chiral Cores Type III Chiral Nematic Liquid Crystals Cholesteryl Esters Chiral Mesogens Derived from Cyclohexane Chiral Heterocyclic Mesogens Axially Chiral Liquid Crystals Axially Chiral Alkenes and Overcrowded Alkenes Allenes Tricyclo[4.4.0.0 3,8 ]decane or Twistane Derived Mesogens Sterically Hindered Biphenyl Derivatives Spirobiindane Derivatives Concluding Remarks

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“…Optically active nonsymmetric dimers comprising cholesterol and aromatic mesogenic entities interlinked through a flexible spacer are well known to exhibit remarkable mesomorphic properties (1)(2)(3)(4)(5)(6)(7)(8). Such properties of these cholesterol-based dimers primarily depend on the nature of the aromatic mesogenic unit, in addition to the length and parity of the spacer.…”

Section: Introductionmentioning

confidence: 99%

Crystal structure of an optically active non-symmetric liquid crystal dimer: cholesteryl 5-[4-(4-n-heptylphenylethynyl)phenoxy]pentanoate

et al. 2009

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2009) Crystal structure of an optically active non-symmetric liquid crystal dimer: cholesteryl 5-[4-(4-n-heptylphenylethynyl)phenoxy]pentanoate, Liquid Crystals, 36:3, 225-230, The crystal structure of cholesteryl 5-[4-(4-n-heptylphenylethynyl)phenoxy]-pentanoate (C 53 H 76 O 3 ) was determined by direct methods using single crystal X-ray diffraction data. It crystallises in the triclinic system with space group P1 and Z = 2. The unit cell parameters are: a = 10.6791(5), b = 13.0903(7), c = 18.6430(9)Å , = 94.413(3), = 98.222(3), = 112.987 (3) . The final reliability factor was R = 0.0510 for 7284 observed reflections and the goodness of fit was equal to 1.062. The asymmetric unit cell of the compound was found to contain two symmetryindependent molecules, A and B. In both molecules, the six-membered rings of the cholesterol moiety are conformationally very similar. However, pronounced differences were observed in the conformation of the fivemembered ring, which is a half-chair in molecule A and assumes an envelope conformation in molecule B. In both molecules, the phenyl rings are planar. The dihedral angle between the two phenyl rings is 43.4(2) and 42.7(2) for molecules A and B, respectively. The packing of molecules in the crystalline state was found to be a precursor to the smectic A phase structure. The crystal structure is stabilised by inter-molecular C-H. . .O and C-H. . . interactions.

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Cholesterol-based nonsymmetric liquid crystal dimers: an overview

Cited by 133 publications

References 103 publications

Optically active, mesogenic lanthanide complexes: design, synthesis and characterisation

Optically active, mesogenic lanthanide complexes: design, synthesis and characterisation

Design and Synthesis of Chiral Nematic Liquid Crystals

Crystal structure of an optically active non-symmetric liquid crystal dimer: cholesteryl 5-[4-(4-n-heptylphenylethynyl)phenoxy]pentanoate

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