Design of Biaxial Nematic Mesogens

Lehmann, Matthias; Görtz, Verena

doi:10.1002/9783527671403.hlc049

Cited by 4 publications

(1 citation statement)

References 160 publications

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“…They showed the existence of two uniaxial ( N D , discotic; and N C , calamitic) phases and a biaxial ( N B ) nematic phase, confirming the theoretical predictions of Freiser [2] and Alben [3]. This fascinating field of research remains active, as evidenced by the interest demonstrated by experimentalists and theoreticians in the last decade [4,5,6,7,8]. …”

Section: Introductionsupporting

confidence: 61%

New Lyotropic Mixtures with Non-Chiral N-Acylamino Acid Surfactants Presenting the Biaxial Nematic Phase Investigated by Laser Conoscopy, Polarized Optical Microscopy and X-ray Diffraction

et al. 2014

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Amino acid-based surfactants were used as the main surfactants to prepare new lyotropic mixtures presenting three nematic phases. One of them is biaxial (NB), and the two others are uniaxial, discotic (ND) and calamitic (NC). These surfactants were the non-chiral molecules, potassium N-dodecanoyl-dl-alaninate (dl-KDDA), potassium N-dodecanoyl-dl-serinate (dl-KDDS), disodium N-dodecanoyl-dl-aspartate (dl-NaDDAs) and potassium N-dodecanoyl-glycinate (KDDGly). Measurements of the optical birefringences and X-ray diffraction analysis were used to characterize the nematic phases and phase transitions. Mixtures with dl-KDDS exhibited the largest biaxial phase domain (~9 °C) with respect to the other mixtures in this study. The results obtained with the KDDGly mixture showed that the existence of hydrogen bonding between the head groups of the surfactant molecules seems to hinder the orientation of the micelles under the action of an external magnetic field.

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Section: Introductionsupporting

confidence: 61%

New Lyotropic Mixtures with Non-Chiral N-Acylamino Acid Surfactants Presenting the Biaxial Nematic Phase Investigated by Laser Conoscopy, Polarized Optical Microscopy and X-ray Diffraction

et al. 2014

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Discotic Star Mesogen with Thymine Nucleobases Exhibiting a Rare Gyroid Cubic Mesophase with 3D Conductivity

Noll,

Lambov,

Singh

et al. 2023

Chemistry A European J

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A unique gyroid cubic phase has been discovered for a discotic star mesogen with three covalently attached DNA bases. In this cubic [[EQUATION]] phase, the conjugated core of the mesogens and the thymine pseudo guests self‐assemble in mirror image continuous networks, representing a semiconducting material with three‐dimensional transport pathways. The hole carrier mobilities are found to be in the typical range of poly(phenylenevinylene) scaffolds. This structure is stabilized by a weak hydrogen bonding between the thymine bases and can be switched to a columnar liquid crystal – thermally and by the addition of complementary adenine guests.

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The Interplay of Spacer Chirality and Parity in Mesogenic Dimers

Ožegović,

Knežević,

Novak

et al. 2024

ChemPhysChem

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Introducing chirality into soft materials, including liquid crystals (LCs), profoundly impacts their self‐organization and physical properties. In this study, we synthesized a novel series of LC dimers with a chiral center as part of their flexible spacer. The dimers were prepared in racemic and enantiomerically pure forms. Their spacer length and parity were varied to investigate the effect of spacer chirality and parity on mesomorphic behavior and on chiral induction in the nematic phase of achiral mesogens. Our results show that the even‐membered chiral dimers only have chiral nematic phases. In contrast, the odd‐membered dimers display rich mesomorphism, including the intriguing blue phase (BP) and chiral form of the twist‐bend nematic phase (N*TB). The observed significant difference in the 3D surface morphology between the racemic and chiral forms of the N*TB phase suggests that the chiral moiety in the spacer promotes a chiral hierarchy. Furthermore, the chiral dimers show a prominent odd‐even effect in the helical twisting power in nematic hosts. These findings highlight the importance of the position of the chiral group within the dimeric molecule and provide new insights into how intrinsic chirality in the spacer affects the overall structural chirality.

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Design of Biaxial Nematic Mesogens

Cited by 4 publications

References 160 publications

New Lyotropic Mixtures with Non-Chiral N-Acylamino Acid Surfactants Presenting the Biaxial Nematic Phase Investigated by Laser Conoscopy, Polarized Optical Microscopy and X-ray Diffraction

New Lyotropic Mixtures with Non-Chiral N-Acylamino Acid Surfactants Presenting the Biaxial Nematic Phase Investigated by Laser Conoscopy, Polarized Optical Microscopy and X-ray Diffraction

Discotic Star Mesogen with Thymine Nucleobases Exhibiting a Rare Gyroid Cubic Mesophase with 3D Conductivity

The Interplay of Spacer Chirality and Parity in Mesogenic Dimers

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