The optical anisotropy and orientational order parameter of two mesogens having slightly different flexible side chain – a comparative study

Patari, Sangita; Chakraborty, Santanu; Nath, A.

doi:10.1080/02678292.2016.1155767

Cited by 12 publications

(9 citation statements)

References 28 publications

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“…It was clear that as the temperature increases, the no values increase and the ne values decrease. The effective geometry αeg is the dispersion of light in liquid crystals that can be obtained by the following equation [49][50][51]:…”

Section: Measurements Of Refractive Indexmentioning

confidence: 99%

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Mesomorphic, Optical and DFT Aspects of Near to Room-Temperature Calamitic Liquid Crystal

et al. 2020

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A new liquid crystalline, optical material-based Schiff base core with a near to room-temperature mesophase, (4-methoxybenzylideneamino)phenyl oleate (I), was prepared from a natural fatty acid derivative, and its physical and chemical properties investigated by experimental and theoretical approaches. The molecular structure was confirmed by elemental analysis, FT-IR (Fourier-Transform-Infrared Spectroscopy) and NMR (nuclear magnetic resonance) spectroscopy. Optical and mesomorphic activities were characterized by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The results show that compound (I) exhibits an enantiotropic monomorphic phase comprising a smectic A phase within the near to room-temperature range. Ordinary and extraordinary refractive indices as well as birefringence with changeable temperatures were analyzed. Microscopic and macroscopic order parameters were also calculated. Theoretical density functional theory (DFT) calculations were carried out to estimate the geometrical molecular structures of the prepared compounds, and the DFT results were used to illustrate the mesomorphic results and optical characteristics in terms of their predicted data. Three geometrical isomers of the prepared compound were investigated to predict the most stable isomer. Many parameters were affected by the geometrical isomerism such as aspect ratio, planarity, and dipole moment. Thermal parameters of the theoretical calculations revealed that the highest co-planar aromatic core is the most stable conformer.

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Section: Measurements Of Refractive Indexmentioning

confidence: 99%

“…The αeg values reach unity in the isotropic phase because the molecular orientation order in the sample used vanished [52,53]. The effective geometry α eg is the dispersion of light in liquid crystals that can be obtained by the following equation [49][50][51]:…”

Section: Measurements Of Refractive Indexmentioning

confidence: 99%

Mesomorphic, Optical and DFT Aspects of Near to Room-Temperature Calamitic Liquid Crystal

et al. 2020

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“…where α and ∆α are the mean molecular polarizability and the anisotropy polarizability, respectively. The scaling factor ∆α/α was obtained by using Haller's extrapolation method, and by substituting in Equation (5), the order parameter S could be calculated for each sample [20,21,83]. Figure 14 shows the correlation between S and ∆n for the compounds I, II, I/II and I/III, which was directly proportional.…”

Section: Order Parameters Measurementsmentioning

confidence: 99%

“…Figure 11 shows the values of ∆n = n e − n o for the compounds I, II, I/II and I/III, which were obtained by measuring n o and n e at a variable temperature by using a laser light source of wavelength (543 nm). It was noticed that as the temperature increased, the ∆n values decreased gradually [81][82][83][84][85][86]. Birefringence n of the LC is one of the essential parameters for LCs, which affects the operation of the electro-optic devices [81][82][83].…”

mentioning

confidence: 99%

“…It was noticed that as the temperature increased, the ∆n values decreased gradually [81][82][83][84][85][86]. Birefringence n of the LC is one of the essential parameters for LCs, which affects the operation of the electro-optic devices [81][82][83]. Figure 11 shows the values of n = ne -no for the compounds I, II, I/II and I/III, which were obtained by measuring no and ne at a variable temperature by using a laser light source of wavelength (543 nm).…”

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Optical and Geometrical Characterizations of Non-Linear Supramolecular Liquid Crystal Complexes

et al. 2020

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Nonlinear architecture liquid crystalline materials of supramolecular 1:1 H-bonded complexes (I/II and I/III) were prepared through a self-assembly intermolecular interaction between azopyridine (I) and 4-n-alkoxybenzoic acid (II) as well as 4-n-alkoxyphenylazo benzoic acid (III). The H-bond formation of the prepared supramolecular hydrogen bonded (SMHB) complexes was confirmed by Fourier-transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Optical and mesomorphic behaviors of the prepared complexes were studied by polarized optical microscopy (POM) as well as DSC. Theoretical calculations were performed by the density functional theory (DFT) and used to predict the molecular geometries of the synthesized complexes, and the results were used to explain the experimental mesomorphic and optical properties in terms of their estimated thermal parameters. Ordinary and extraordinary refractive indices as well as birefringence at different temperatures were investigated for each sample using an Abbe refractometer and modified spectrophotometer techniques. Microscopic and macroscopic order parameters were calculated for individual compounds and their supramolecular complexes.

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Impact of fluorine orientation on the optical properties of difluorophenylazophenyl benzoates liquid crystal

Zaki

Ahmed

Hagar

2018

Materials Chemistry and Physics

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The optical anisotropy and orientational order parameter of two mesogens having slightly different flexible side chain – a comparative study

Cited by 12 publications

References 28 publications

Mesomorphic, Optical and DFT Aspects of Near to Room-Temperature Calamitic Liquid Crystal

Mesomorphic, Optical and DFT Aspects of Near to Room-Temperature Calamitic Liquid Crystal

Optical and Geometrical Characterizations of Non-Linear Supramolecular Liquid Crystal Complexes

Impact of fluorine orientation on the optical properties of difluorophenylazophenyl benzoates liquid crystal

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