Heterocyclic pyridine-based liquid crystals: synthesis and mesomorphic properties

Ong, Lay Khoon; Ha, Sie‐Tiong; Yeap, Guan Yeow; Lin, Hong‐Cheu

doi:10.1080/02678292.2018.1455225

Cited by 49 publications

(21 citation statements)

References 42 publications

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“…The above-mentioned classes of hybrid materials are one of the ways to meet the growing demand for specialized materials. Another way is the chemical synthesis of extremely complex organic materials, including the use of longer alkyl substituents, increasing the number of benzene rings in a rigid core and the presence of heteroatoms (such as S, N) [ 1 , 2 , 3 , 4 ]. Another possibility is, for example, to introduce lactate groups into the structure of organic compounds or fabrication of a polymer-dispersed liquid crystal [ 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

Modifications of FLC Physical Properties through Doping with Fe2O3 Nanoparticles (Part I)

et al. 2021

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The aim of this paper is to show, by systematic studies, the influence of γ-Fe2O3 nanoparticles on the physical parameters of the liquid crystalline matrix, exhibiting a ferroelectric phase in a wide temperature range. The detailed research was carried out by using diffraction (PXRD), microscopic (OM, SEM, FCPM, POM), thermal (DSC), optical (TLI), electric and spectroscopic (FTIR) methods. We show that even the smallest concentration of γ-Fe2O3 nanoparticles largely modifies the parameters of the ferroelectric SmC* phase, such as spontaneous polarization, switching time, tilt angle, rotational viscosity, dispersion anchoring energy coefficient and helix pitch. The admixture also causes a significant reduction in the temperature of phase transitions, broadening the SmA* phase at the expense of the SmC* phase and strong streaking of the texture. We present and explain the non-monotonic modification of these parameters with an increase in the nanoparticle concentration. The influence of oleic acid admixture on these parameters is also widely discussed. We have shown that certain parameters of organic-metal nanocomposites can be controlled by the appropriate amount of metal admixture.

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Section: Introductionmentioning

confidence: 99%

Modifications of FLC Physical Properties through Doping with Fe2O3 Nanoparticles (Part I)

et al. 2021

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“…Smaller thermal ranges of mesomorphic phase than those of the pure alkoxy benzoic acid dimeric mesogens were observed in the 144a-b/145a-g complexes with two aromatic rings. Ong et al 63 synthesized calamitic mesogens, 4-{[(pyridin-4-yl) methylidene]amino}phenyl 4-alkoxybenzoates (152a-i), containing pyridine heterocycles and a two-phenyl core ring system, imine linkage, ester linkage, and alkoxy chain (which was varied as n ¼ 2, 4,6,8,10,12,14,16,18). Further, they referred to previous reports by Ha et al 64 and Kadkin et al 65 to synthesize the compounds 4-[(pyridine-4-ylmethylene)amino]phenol (148) and 4-alkoxybenzoic acid (151a-i), respectively.…”

Section: Pyridine-based Molecules As Thermotropic Mesogensmentioning

confidence: 99%

Recent synthetic advances in pyridine-based thermotropic mesogens

Devadiga

Ahipa

2019

RSC Adv.

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“…In the last few years, interesting studies of heterocyclic liquid crystal compounds comprising azopyridene moieties have been prepared and their mesomorphic properties were characterized [1][2][3][4][5][6][7][8][9][10][11]. The incorporation of heterocyclic rings with electronegative hetero-atoms (N, O or S) will enhance and impact powerful polar induction [12].…”

Section: Introductionmentioning

confidence: 99%

Induced Wide Nematic Phase by Seven-Ring Supramolecular H-Bonded Systems: Experimental and Computational Evaluation

et al. 2020

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New seven-ring systems of dipyridine derivative liquid crystalline 2:1 supramolecular H-bonded complexes were formed between 4-n-alkoxyphenylazo benzoic acids and 4-(2-(pyridin-4-yl)diazenyl)phenyl nicotinate. Mesomorphic behaviors of the prepared complexes were investigated using a combination of differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Fermi bands attributed to the presence of intermolecular H-bond interactions were confirmed by FT–IR spectroscopy. All prepared complexes possessed an enantiotropic nematic phase with a broad temperature nematogenic range. Phases were confirmed by miscibility with a standard nematic (N) compound. A comparison was constructed to investigate the influence of the incorporation of the azophenyl moiety on the mesomeric behavior of corresponding five-membered complexes. It was found that the present complexes observed induced a wide nematic phase with relatively higher temperature ranges than the five aromatic systems. Density functional theory (DFT) suggested the nonlinear geometry of the formed complex. The results of the DFT explained the nematic mesophase formation. Moreover, the π–π stacking of the aromatic moiety in the phenylazo acid plays an effective role in the mesomorphic thermal stability. The energy difference between the frontier molecular orbitals, HOMO (highest occupied) and LUMO (lowest occupied), and the molecular electrostatic potential (MEP) of the prepared complexes were estimated by DFT calculations. The results were used to illustrate the observed nematic phase for all H-bonded supramolecular complexes. Finally, photophysical studies were discussed which were carried out by UV spectroscopy connected to a hot stage.

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Heterocyclic pyridine-based liquid crystals: synthesis and mesomorphic properties

Cited by 49 publications

References 42 publications

Modifications of FLC Physical Properties through Doping with Fe2O3 Nanoparticles (Part I)

Modifications of FLC Physical Properties through Doping with Fe2O3 Nanoparticles (Part I)

Recent synthetic advances in pyridine-based thermotropic mesogens

Induced Wide Nematic Phase by Seven-Ring Supramolecular H-Bonded Systems: Experimental and Computational Evaluation

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