Structural ordering and molecular-optical properties of a discotic liquid crystal (Col<sub>ho</sub>)

Gunyakov, V. A.; Shibli, S. M.

doi:10.1080/0267829021000043321

Cited by 10 publications

(10 citation statements)

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“…only, since was discovered by refraction measurements [11], confirms the constancy of the oscillator strength A m . only, since was discovered by refraction measurements [11], confirms the constancy of the oscillator strength A m .…”

Section: Resultsmentioning

confidence: 70%

“…only, since was discovered by refraction measurements [11], confirms the constancy of the oscillator strength A m . Thus, the difference between mean values of the effective polarizability g g, of about 6 Å in the columnar and isotropic phases [11], is caused not only by the features of the local-field effects in these phases, but also by the alteration of the conformation of discogenic molecular cores at Col ho -I transition. S 4 transition in the Col ho phase of H7T is caused by the mixing effects only.…”

Section: Resultsmentioning

confidence: 70%

“…3), we used the experimental values of the refractive indices measured in the region of the wavelengths 488-633 nm [11] and single-band dispersion relation n 2 o;i ¼ 1 þ l 2 A ? To obtain the background refractive indices at l ¼ 270 nm (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Conformation and Electronic Structure Studies of Molecules at the Col HO - I Phase Transition in Columnar Discotic Liquid Crystal

Gunyakov

Shibli

2003

Molecular Crystals and Liquid Crystals

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The changes of the electronic structure of molecules in the columnar discotic liquid crystal 2,3,6,7,10,11-hexaheptyloxytriphenylene were studied by using the polarized electronic absorption measurements. The detailed analysis of the spectral data showed that a mixing of electronic excitations is present in discotics and that it affects the measured values of the optical density and the oscillator strength of the electronic absorption bands. The changes in the oscillator strength of the long-wavelength electronic transition and the conformation of the aromatic molecular cores have been discovered experimentally upon the isotropic -columnar phase transition.

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Section: Resultsmentioning

confidence: 70%

Section: Resultsmentioning

confidence: 70%

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Conformation and Electronic Structure Studies of Molecules at the Col HO - I Phase Transition in Columnar Discotic Liquid Crystal

Gunyakov

Shibli

2003

Molecular Crystals and Liquid Crystals

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“…The DLC shows uniaxial phase behaviour. [28] Therefore, the homeotropic alignment of discotic molecules does not show the birefringence Table 1. The peak transition temperatures (T P in C) at the scan rate 5 C/min, average of enthalpies (DH in J/g) and entropies (DS in mJ/g K) for various transitions deduced from the thermodynamic studies for HAT4 and HAT4 C 0.6 wt% CuNPs.…”

Section: Resultsmentioning

confidence: 99%

Effects of copper nanoparticles on the thermodynamic, electrical and optical properties of a disc-shaped liquid crystalline material showing columnar phase

2015

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Thermodynamic, electrical and optical studies have been carried out on a discotic liquid crystal (DLC), namely 2, 3, 6, 7, 10, 11-hexabutyloxytriphenylene (possessing columnar phase) and its copper nanoparticles (0.6 wt%) based composite. The ionic conductivity of DLCÀcopper nanocomposite has increased by about two orders of magnitude as compared to the pure system. Dielectric permittivity has also increased. The absorption spectra for pure and nanocomposites have been studied by UVÀVis spectrophotometer. The optical study suggests that surface plasmon resonance has been introduced in DLC due to the incorporation of copper nanoparticles. It has been observed that the presence of nanoparticles has decreased the optical band gap to 3.3 eV from 4.2 eV of the pure DLC. Enhanced properties are useful for onedimensional conduction and photovoltaic applications.

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“…The homeotropically aligned discotic liquid crystals show uniaxial phase behaviour. [34] Therefore, the homeotropic alignment of discotic molecules does not show the birefringence under the PLM between crosspolarisers. Thus, the refractive indices of homeotropically aligned pure and composite materials have been estimated using the relationship:…”

Section: Dielectric Investigationsmentioning

confidence: 99%

Effect of silver nanoparticles on frequency and temperature-dependent electrical parameters of a discotic liquid crystalline material

et al. 2015

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The effect of silver nanoparticles (AgNPs) of diameters 6 and 100 nm on a discotic liquid crystalline material, namely 2,3,6,7,10,11-hexabutyloxytriphenylene (in short HAT4), has been observed in thermodynamic, electrical and optical texture studies. Silver nanoparticles (0.6 wt%) of diameter~6 nm demonstrate a negligible (but 100 nm shows appreciable) effect on the broad temperature range plastic columnar hexagonal (Col hex ) phase (~65.0°C) of pure HAT4. The dielectric studies have been carried out in the frequency range of 10 Hz-35 MHz under homeotropic anchoring conditions of the molecules. In the low frequency region of pure HAT4 and its AgNP composites, a relaxation mode has been observed. AgNPs of 6 nm elevate the value of dielectric permittivity of the plastic columnar hexagonal phase of pure HAT4. The dc conductivity of pure HAT4 and its AgNP composite (6 and 100 nm) material has been determined. The optical band gap for pure and AgNP composites of HAT4 has been determined by the ultraviolet-visible study. Due to insertion of AgNPs, the optical band gap of HAT4 has reduced.

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Structural ordering and molecular-optical properties of a discotic liquid crystal (Col_ho)

Cited by 10 publications

References 9 publications

Conformation and Electronic Structure Studies of Molecules at the Col HO - I Phase Transition in Columnar Discotic Liquid Crystal

Conformation and Electronic Structure Studies of Molecules at the Col HO - I Phase Transition in Columnar Discotic Liquid Crystal

Effects of copper nanoparticles on the thermodynamic, electrical and optical properties of a disc-shaped liquid crystalline material showing columnar phase

Effect of silver nanoparticles on frequency and temperature-dependent electrical parameters of a discotic liquid crystalline material

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Structural ordering and molecular-optical properties of a discotic liquid crystal (Colho)

Cited by 10 publications

References 9 publications

Conformation and Electronic Structure Studies of Molecules at the Col HO - I Phase Transition in Columnar Discotic Liquid Crystal

Conformation and Electronic Structure Studies of Molecules at the Col HO - I Phase Transition in Columnar Discotic Liquid Crystal

Effects of copper nanoparticles on the thermodynamic, electrical and optical properties of a disc-shaped liquid crystalline material showing columnar phase

Effect of silver nanoparticles on frequency and temperature-dependent electrical parameters of a discotic liquid crystalline material

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Structural ordering and molecular-optical properties of a discotic liquid crystal (Col_ho)