The Polymorphism of Liquid Crystals

Sackmann, H.; Demus, D.

doi:10.1080/15421406608083062

Cited by 216 publications

(42 citation statements)

References 3 publications

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“…The transition temperatures, enthalpy changes, and phase sequences are summarized in Figure 1. Phase identification was based on the optical textures, and the magnitude of isotropization on enthalpies is consistent with the assignment of each mesophase type, using the classification systems reported by Sackmann and Demus [24] and Gray and Goodby [25]. Under POM, focal conic fanshaped and homeotropic textures of a smectic A (SmA) phase was observed during the cooling cycle (Figure 4).…”

Section: Mesomorphic Propertiessupporting

confidence: 68%

Synthesis and Mesomorphic Properties of New Fluorinated Schiff Base Liquid Crystals

Lee

2014

ISRN Materials Science

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Two new compounds, 4-alkanoyloxybenzylidene-4 -fluoroaniline and 4-fluorobenzylidene-4 -n-alkanoyloxyaniline comprising a terminal fluorosubstituent were studied. The fluoro substituent contributes to the molecular polarizability, thus affecting intermolecular interactions and hence resulting in smectic mesomorphism. The mesomorphic properties were studied using differential scanning calorimetry and polarizing optical microscopy techniques. The mesomorphic properties of compounds studied are strongly dependent on the orientation of the imine (CH=N) linkage. The former Schiff base exhibited smectic A phase whereas the latter compound did not display any mesophase. Reversed imine linkage has caused depression of mesomorphic property in the compound studied (4-fluorobenzylidene-4 -n-alkanoyloxyaniline). The mesomorphic properties of the present compounds were compared with other structurally related series to establish the chemical structure-mesomorphic property relationship.

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Section: Mesomorphic Propertiessupporting

confidence: 68%

Synthesis and Mesomorphic Properties of New Fluorinated Schiff Base Liquid Crystals

Lee

2014

ISRN Materials Science

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“…The transition temperatures and phase sequences are summarize in Table 3. Phase identification was based on the optical textures, and the magnitude of isotropization on enthalpies is consistent with the assignment of each mesophase type, using the classification systems reported by Sackmann and Demus (1966) and Gray and Goodby (1984) [18][19]. Under POM, nematic texture was observed (Fig.(5)).…”

Section: Mesomorphic Propertiessupporting

confidence: 57%

Schiff Base liquid Crystals with Terminal Alkoxy Group Synthesis and Thermotropic Properties

Jber

Shukur

Najaf

2017

JNUS

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A new homologous series of Schiff base esters comprising a terminal alkoxy substituent N-{(nalkoxy-4``-bezoyloxy)-4`-benzylidene}-4-butyl aniline was studied. The alkyloxy substituent contributes to the molecular polarizability, thus, affecting intermolecular interactions, hence, resulting in nematic polymorphism. The mesomorphic properties were studied using polarizing optical microscope (POM). The lower members, n-methoxy and n-ethoxy derivatives were nonmesogens, enantiotropic nematogenic phase was observed on further lengthening of the alkyl chain from C3 to C6 and smectogenic phase was observed for compounds C7 and C8. FT-IR, 1 HNMR, 13 CNMR, EI-MS and elemental analysis were employed to elucidate the molecular structure of the title compounds whereas the liquid crystal properties were determined by POM analysis. The mesomorphic behaviors of the homologous compounds are rationalized based on the varying lengths of the alky chain.

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“…3) [14]. The identification of the liquid crystal phase by contact preparation is based on the rule of miscibility proposed by Sackmann and Demus [15]. If the unknown phase is miscible with a reference phase over the entire concentration range then these two phases are equivalent while if the two phases are not miscible no www.crt-journal.org conclusion can be drawn.…”

Section: Resultsmentioning

confidence: 99%

Smectic phases of liquid crystals based on dinuclear palladium(II) complexes with carboxylato bridge

Cı̂rcu

Simonescu

2010

Cryst. Res. Technol.

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In this paper we present the preparation and the investigation of the liquid crystal properties of a series of dinuclear carboxylato bridge Pd(II) complexes bearing six alkoxy peripheral chains in the molecule. Their structures were assigned based on elemental analysis, IR and 1 H NMR spectroscopy whereas the thermal behaviour was investigated by polarizing optical microscopy and differential scanning calorimetry. The monotropic smectic A phase displayed by these materials was identified by miscibility studies with a previously reported mesogen. It was found that the transition temperatures and the SmA mesophase stability depend on the alkyl chain length of the carboxylato bridge.

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The Polymorphism of Liquid Crystals

Cited by 216 publications

References 3 publications

Synthesis and Mesomorphic Properties of New Fluorinated Schiff Base Liquid Crystals

Synthesis and Mesomorphic Properties of New Fluorinated Schiff Base Liquid Crystals

Schiff Base liquid Crystals with Terminal Alkoxy Group Synthesis and Thermotropic Properties

Smectic phases of liquid crystals based on dinuclear palladium(II) complexes with carboxylato bridge

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