Liquid crystal tetramers: influence of molecular shape on liquid crystal behaviour

Henderson, Peter A.; Imrie, Corrie T.

doi:10.1080/02678290500410620

Cited by 60 publications

(17 citation statements)

References 42 publications

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“…The behaviour may be contributed by the position of the mesogenic linkage of the triazole core which introduces an aspect of non-linearity into the even membered dimers, therefore, the two innermost mesogenic units are no longer planar. [51] As a consequence, the molecular arrangement for both the odd and even members can be considered as a bent shape. This phenomenon can be observed in other oligomers such as trimers and tetramers.…”

Section: Liquid Crystalsmentioning

confidence: 99%

Non-symmetrical liquid crystal dimers armed with azobenzene and 1,2,3-triazole-cholesterol

et al. 2015

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New non-symmetrical dimers which contain respective side units of azobenzene and 1,2,3-triazole-choloesteral have been synthesised from the reaction between 6-azido-[4-(4-acetylphenylazo)phenoxy]alkane and cholesteryl-4-(prop-2-ynyloxy)benzoate. The results show that the derivatives of 6-bromo[4-(4-acetylphenylazo)phenoxy] alkanes which possess the odd alkyl spacers exhibit dimesomorphism of N and SmA phases whilst the members with even numbers are non-mesogenic. However, the 6-azido-[4-(4-acetylphenylazo)phenoxy]-alkanes show N and SmA phases in a wide temperature range. On heating and cooling the target compounds cholesteryl 4-[(1-(6-(4-(4ʹ-acetylphenylazo)phenoxy)alkyl)-1H-1,2,3-triazol-4-yl)methoxy]benzoate show chiral nematic (oily streak and fanshaped texture) and focal conic texture characteristics of smectic A phases with high thermal stability. Present investigation also reveals the effect of the spacer length upon the phase transition temperature. Intercalated arrangement is favoured by the molecules in the smectic phase. The observation is well established by XRD measurement wherein the actual molecular length is smaller than the theoretical value.

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Section: Liquid Crystalsmentioning

confidence: 99%

Non-symmetrical liquid crystal dimers armed with azobenzene and 1,2,3-triazole-cholesterol

et al. 2015

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“…Percec et al [25] reported the transition properties of the LC copolymers containing odd-and evenmembered flexible spacers. Henderson and Imrie reported the transition properties of the LC trimers [12] and the LC tetramers [13,14] containing odd-and even-membered flexible spacers. In the present report, the transition properties of the four types of trimers and of tetramers were compared in order to elucidate an effect of combining of different flexible spacers in LC trimers (1) and tetramers (2).…”

Section: Introductionmentioning

confidence: 99%

“…These molecules exhibit a remarkable odd-even effect in their transition properties, which depends on the length and parity of the flexible spacer. The structure property relationships in LC trimers and tetramers have been studied by a number of researchers [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], and we have also studied odd-even effects in LC trimers (1) [21] and tetramers (2) [22]. The molecules (1) and (2) contain two kinds of flexible spacers, namely O(CH 2 ) m O and COO(CH 2 ) n O groups.…”

Section: Introductionmentioning

confidence: 99%

Effects of combining of different flexible spacers in liquid crystal trimers and tetramers on transition properties

Itahara

2010

Liquid Crystals

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Liquid crystal trimers and tetramers containing two kinds of flexible spacers, namely O(CH 2 ) m O and COO(CH 2 ) n O, were divided into four classes according to the odd/even nature of the number of atoms in the flexible spacers: specifically, even-even, odd-odd, even-odd, and odd-even trimers, and even-even-even, odd-odd-odd, odd-even-odd, and even-odd-even tetramers. The transition properties of the four types of trimers and of tetramers were compared. Although the nematic-isotropic transition temperature and the associated entropy changes were primarily related to the number of the even-membered flexible spacers in these molecules, the different combinations of the flexible spacers significantly affected their transition properties.

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“…Such studies are not only of academic value in understanding the structural and mechanistic aspects of phase transitions, but they can also be of technological importance [11].…”

Section: Introductionmentioning

confidence: 99%

Computer Simulations of Ordering in a Nematogen – The Role of Dielectric Medium

Praveen¹,

Ojha²

2010

Zeitschrift Für Naturforschung A

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Computer simulations of ordering in a nematic liquid crystal propyl 4-(4 -methoxybenzylidene amino)-α-methyl cinnamate (MBA2C3) was carried out with respect to translatory and orientational motions. The evaluation of atomic charges and dipole moment at each atomic center was carried out through the complete neglect differential overlap (CNDO/2) method. The modified RayleighSchrödinger perturbation method along with multicentered-multipole expansion method has been employed to evaluate long-range intermolecular interactions, while a '6-exp' potential function has been assumed for short-range interactions. The total interaction energy values obtained through these computations were used to calculate the probability of each configuration in a dielectric medium (i. e., non-interacting and non-mesogenic solvent, e. g. benzene) at room temperature (300 K) using the Maxwell-Boltzmann formula. On the basis of stacking, in-plane, and terminal interaction energy calculations, all possible geometrical arrangements of pairs have been considered. The most favourable configuration of pairing has been obtained. An attempt has been made to develop a new and interesting molecular model of nematogen in dielectric medium.

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Liquid crystal tetramers: influence of molecular shape on liquid crystal behaviour

Cited by 60 publications

References 42 publications

Non-symmetrical liquid crystal dimers armed with azobenzene and 1,2,3-triazole-cholesterol

Non-symmetrical liquid crystal dimers armed with azobenzene and 1,2,3-triazole-cholesterol

Effects of combining of different flexible spacers in liquid crystal trimers and tetramers on transition properties

Computer Simulations of Ordering in a Nematogen – The Role of Dielectric Medium

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