Halogenation in Achiral Calamitic Liquid Crystals. II Terminal and Linking Substitutions

Petrov, Vladimir F.

doi:10.1080/15421400903507763

Cited by 4 publications

(1 citation statement)

References 79 publications

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“…Herein, we would also like to focus on the comparison between compounds 4a and 7a which structurally differs by the nature of the halogen atom on the pyridine group and the position of the nitrogen. It is known that the nature of halogen groups plays a significant role in the intraand inter-molecular interactions [43] which affect the packing of the molecules, that predominantly influences mesophase stability. The main reason is not the strong polar interactions at interfaces, as previously postulated in the literature.…”

Section: Liquid Crystalline Propertiesmentioning

confidence: 99%

Pyridine-based chiral smectogens: effects of polar end groups on liquid crystal properties

et al. 2020

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In this study, novel chiral pyridine-based rod-like mesogens, consisting of a chloro or bromo group substituted pyridine head core which is connected to one or two aromatic rings through ester linkers and a flexible (S)-2-methylbutoxy or (S)-3,7-dimethyloctyloxy chiral end chain have been synthesized. The liquid crystal properties of new compounds were investigated by various experimental techniques such as DSC, POM and SAXS. Depending of the nature of the halogen end group, the derivatives with two aromatic rings are non-mesogenic compounds whereas a smectic A phase (SmA) enantiotropically occurs for the members with three aromatic rings of the series. Additionally, chloro group substituted compound composed of three aromatic rings carrying a (S)-2-methylbutoxy end chain exhibits an enantiotropic chiral nematic phase (N*).

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Section: Liquid Crystalline Propertiesmentioning

confidence: 99%

Pyridine-based chiral smectogens: effects of polar end groups on liquid crystal properties

et al. 2020

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Microsegregation in Polyphilic Calamitic, Disklike,and Bent‐Core Mesogens

Tschierske

2014

Handbook of Liquid Crystals

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Orientational ordering studies of fluorinated thermotropic liquid crystals by NMR spectroscopy

Calucci

Geppi

Urban

2014

Magnetic Reson in Chemistry

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Fluorinated calamitic thermotropic liquid crystals represent an important class of materials for high-tech applications, especially in the field of liquid crystal displays. The investigation of orientational ordering in these systems is fundamental owing to the dependence of their applications on the anisotropic nature of macroscopic optical, dielectric, and visco-elastic properties. NMR spectroscopy is the most powerful technique for studying orientational order in liquid crystalline systems at a molecular level thanks to the possibility of exploiting different anisotropic observables (chemical shift, dipolar couplings, and quadrupolar coupling) and nuclei ((2)H, (13)C, and (19)F). In this paper, the basic theory and NMR experiments useful for the investigation of orientational order on fluorinated calamitic liquid crystals are reported, and a review of the literature published on this subject is given. Finally, orientational order parameters determined by NMR data are discussed in comparison to those obtained by optical and dielectric anisotropy measurements.

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Halogenation in Achiral Calamitic Liquid Crystals. II Terminal and Linking Substitutions

Abstract: The effect on the physico-chemical properties of achiral liquid crystals of introducing halogen atoms into their terminal and linking groups is discussed and rationalized in terms of existent theories; a comparison is made with the corresponding hydrogenated and other well-known groups.

Cited by 4 publications

References 79 publications

Pyridine-based chiral smectogens: effects of polar end groups on liquid crystal properties

Pyridine-based chiral smectogens: effects of polar end groups on liquid crystal properties

Microsegregation in Polyphilic Calamitic, Disklike,and Bent‐Core Mesogens

Orientational ordering studies of fluorinated thermotropic liquid crystals by NMR spectroscopy

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