Molecular Structure in Various Phases of Cooled Liquid Crystals

Estrela-llopis, Iryna; Pogorelov, V.; Bukalo, Vyacheslav; Astashkin, Yuri

doi:10.1080/10587259808024382

Cited by 6 publications

(5 citation statements)

References 9 publications

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“…14 At the Crystal II-Sm G transition, there is a rotation around the F-N bond, which is a characteristic feature of this transition. 9 It is to be emphasized that due to the rotation around the F-N bond, the strength of this bond would obviously decrease and thereby, the wavenumber of the corresponding mode will be lowered. The charge cloud shifts to the adjacent ring and the C5N bond.…”

Section: Resultsmentioning

confidence: 99%

“…A good amount of work has been done [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] to study the phase transitions in liquid cr ystals through linear and nonlinear Raman spectroscopy. The importance of the Raman spectroscopic method is that it is a m icroscopic technique whereby a trace of molecular rearrangement in different m esophases can be established, whereas the most widely used traditional techniques 13 to investigate and characterize liquid crystalline phases, viz.…”

Section: Introductionmentioning

confidence: 99%

“…5 The chain length does play an important role for liquid crystal phase stabilization. 3,7,9,10,16,17 The lateral interaction between alkyl chains gives ordered arrangement of chains in a sublayer, and this is more effective for longer alkyl chains. As a result of stabilization of the sublayer due to increased interaction between the chains of the same sublayer, the interaction between the cores is decreased, as shown recently in the case of 4alkyl-4 9-cynobiphenyl.…”

Section: Introductionmentioning

confidence: 99%

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Crystal—Smectic G Transformation Investigated by Temperature-Dependent Raman Study

Singh

Schlücker²,

Asthana³

et al. 2003

Appl Spectrosc

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We report on a temperature-dependent Raman study of terephthalidine-bis-butylaniline (TBBA) and terephthalidine-bis-heptylaniline (TB7A) in the temperature range 10-406 K and in the wavenumber regions 1120-1240 cm-1 and 1500-1700 cm-1. The variations of peak positions and linewidths of several Raman marker bands with temperature, which clearly show crystal-SmG transition at approximately 334 K, have been used to discuss the dynamics of this phase transition. The temperature-dependent Raman study revealed that the increased vibration of the long alkyl tail and the rotation around the long molecular axis are the two primary phenomena responsible for the crystal-SmG transition. Density functional theory (DFT) at the B3LPY/6-31G(d) level was employed to obtain the optimized geometry and the harmonic vibrational wavenumbers of TBBA. The eigenvectors of the modes corresponding to these marker bands were also calculated.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Crystal—Smectic G Transformation Investigated by Temperature-Dependent Raman Study

Singh

Schlücker²,

Asthana³

et al. 2003

Appl Spectrosc

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show abstract

“…Слiд вiдзначити, що для таких представникiв ряду, як МББА, ЕББА, в лiтературi накопиченi майже вичерпнi експериментальнi данi щодо їх структури, фазового полiморфiзму, спектральних властивостей [1][2][3][4][5]. У той час як для iнших речовин, наприклад АБТ, такi данi майже вiдсутнi або зустрiчаються вкрай рiдко.…”

Section: вступunclassified

“…лiчних сполук (5CB, МББА) [6][7][8][9]. Коливальна спектроскопiя може бути корисною для визначення молекулярних конформацiй у рiзних фазових станах та параметрiв порядку, отримання iнформацiї про особливостi мiжмолекулярної взаємодiї та динамiки [10][11][12].…”

Section: вступunclassified

Коливальний Спектр Р-Амілоксібензиліден-Р-Толуідіну В Кристалічній Фазі

Pogorelov¹,

Bukalo²,

Жовтобрюх³

2022

Ukr. J. Phys.

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У роботі виконано аналіз коливального раманівського спектра рідкого кристала p-амілоксібензиліден-p-толуідіну (АБТ).Спектр КРС було зареєстровано в інтервалі 0–1650 cм–1 за кімнатної температури T = 293 К, коли АБТ перебуває у кристалічнійфазі. Проведено квантово-хімічне комп'ютерне моделювання геометрії та розрахунок теоретичних коливальних частот молекули АБТ методом B3LYP/6-31G(d, p). На основі результатів комп'ютерного моделювання виконано інтерпретацію експериментального спектра КРС, отримано конформаційні параметри молекули для кристалічного стану.

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Raman investigation of the low‐temperature phase transition in a liquid crystalline system: terephthalidine‐bis‐heptylaniline (TB7A)

Singh

Schlücker

Asthana

et al. 2002

J Raman Spectroscopy

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Raman spectra of terephthalidine-bis-heptylaniline (TB7A) were recorded in the region 1125-1225 cm −1 from room temperature to 10 K at 18 different temperatures. The splitting of the ∼1165 cm −1 band, and the variation of the ratio of integrated intensities of the original band at ∼1165 cm −1 to the new component at 1170/1171 cm −1 reveals a solid modification. The analysis of the temperature dependence of the linewidth was made using Rakov's relation. A logarithmic plot as a function of 1/T gives two straight lines with an abrupt discontinuity, which clearly exhibits a phase transition at about 210 K. The temperature dependence of the linewidth of the ∼1165 cm −1 band was used to characterize this transition. A relatively large variation (∼3 cm −1 ) of the linewidth on going from 250 to 10 K in TB7A having an odd (n = 7) number of carbon atoms in the alkyl tail compared with those observed (∼1 cm −1 ) in other homologues having an even (n = 2 or 10) number of carbon atoms in the alkyl tail is a clear demonstration of the even-odd effect.

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Molecular Structure in Various Phases of Cooled Liquid Crystals

Cited by 6 publications

References 9 publications

Crystal—Smectic G Transformation Investigated by Temperature-Dependent Raman Study

Crystal—Smectic G Transformation Investigated by Temperature-Dependent Raman Study

Коливальний Спектр Р-Амілоксібензиліден-Р-Толуідіну В Кристалічній Фазі

Raman investigation of the low‐temperature phase transition in a liquid crystalline system: terephthalidine‐bis‐heptylaniline (TB7A)

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