Smectogenic dimeric liquid crystals. The preparation and properties of the α,ω-bis(4-<i>n</i>-alkylanilinebenzylidine-4′-oxy)alkanes

Date, Richard W.; Imrie, Corrie T.; Luckhurst, G. R.; Seddon, John M.

doi:10.1080/02678299208030393

Cited by 298 publications

(100 citation statements)

References 29 publications

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“…The conventional behaviour in liquid crystal dimers is smectic behaviour to be favoured on increasing the spacer length. Since in the present series of compounds nematic phase is favoured in higher methylene spacer containing members this behaviour is unexpected [8][9].…”

Section: Phase Transition and Mesomorphic Behaviourmentioning

confidence: 90%

“…4, the 1,3-dimethyluracil ring and the two phenyl rings (or biphenyl moiety) which is adjacent to the spacer appear at different positions depending on the number of carbons at the alkoxy spacer [34][35][36]. The models indicate that 1.3-dimethyluracil and biphenyl core groups take at different side where the number of carbons at spacer change from n = 6 to 10.…”

Section: Molecular Modelingmentioning

confidence: 99%

“…A wide range of low molar mass dimeric molecular architectures are known to exhibit interesting LC properties when compared to the conventional monomer low molar mass LCs [7]. Moreover, the studies directed toward the dimers are enormous due to their LC favorable chemical structure, size/type of the core, connecting groups and terminal/spacer alkyl chains [8,9].…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and comparative studies of phase transition behaviour of new dimeric liquid crystals consisting of dimethyluracil and biphenyl cores

Mohammad

Srinivasa

et al. 2016

Journal of Molecular Liquids

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A new homologous series of mesogens containing 6-amino-1,3-dimethyluracil moiety have been synthesized. The structures of the compounds were characterised by elemental analysis, FT-IR, 1 H and 13 C NMR spectroscopic techniques. Their mesomorphic properties were studied by polarising optical microscopy attached to a heating stage. Microscopy data were supported with transition temperatures and enthalpy change values obtained from the differential scanning calorimetry analysis. The studies have shown that the mesomorphic properties of the compounds are dependent on the lengths of alkoxy-spacers. Compounds 4a-f with a shorter alkoxyspacer chain (n = 6) exhibited smectic A phase, while compounds 4g-r with a alkoxy-spacer chain (n = 8 or 10) displayed nematic phase.

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Section: Phase Transition and Mesomorphic Behaviourmentioning

confidence: 90%

Section: Molecular Modelingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis and comparative studies of phase transition behaviour of new dimeric liquid crystals consisting of dimethyluracil and biphenyl cores

Mohammad

Srinivasa

et al. 2016

Journal of Molecular Liquids

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“…The compounds were synthesized following a standard procedure as discussed in literature [1,3]. The crude product was repeatedly recrystallized from ethyl acetate until the transition temperatures were found to be constant and reproducible.…”

Section: Methodsmentioning

confidence: 99%

“…Liquid crystal dimers have been attracting a great deal of interest in recent years, both theoretically and experimentally, due to their quite unusual properties compared to low molar mass liquid crystals and their ability to act as model compounds for semi-flexible main-chain liquid crystal polymers [1][2][3][4][5][6][7][8]. They are classified into two categories: symmetric and nonsymmetric dimers.…”

Section: Introductionmentioning

confidence: 99%

Phase transition studies in mesogenic dimers

Gogoi¹,

Alapati²,

Verma³

2002

Cryst. Res. Technol.

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Phase transition studies in mesogenic dimersSchiff base liquid crystal dimers, both symmetric and non-symmetric, in which two anisotropic groups are linked by a flexible spacer, exhibit a rich variety of smectic mesomorphism. The interest in this class of mesogens stems not only from their ability to act as model compounds for semi-flexible mainchain liquid crystal polymers but also from their quite different properties compared to conventional low molar mass liquid crystals (monomers). We report here the phase transition studies on two examples of these schiff base liquid crystal dimers using the Differential Scanning Calorimetry and density measurements as a function of temperature. The symmetric liquid crystal dimer, α,ω-bis (4-ndodecylaniline benzylidene-4′-oxy)decane (10.O12O.10) exhibits a very rare Isotropic to G transition. Where as, the non-symmetric dimer, α-(4-cyano biphenyl-4′-yloxy)-ω-(4-n-decylanilinebenzylidene-4′-oxy)decane (CB.O10O.10) exhibits a rare nematic to intercalated smectic A phase transition. The transitions studied, isotropic to nematic and isotropic to G exhibit a large density jump at the transition confirming their first order nature. Nematic to intercalated smectic A transition is found to be a second order transition whose behavior is similar to nematic to smectic A transition. Calculated values of pressure dependence of transition temperature and thermal expansion coefficient are also reported.

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Nematic Dendrimers Based on Carbosilazane Cores

et al. 2001

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Research on dendritic liquid crystal systems has focused mainly on the investigation of materials that exhibit layered, columnar, cubic-phase structures. [1, 2] The emphasis has been associated with the chemical structure of these systems, in which a dendritic core and a periphery consisting of functional groups of different chemical composition, which are responsible for self-assembly processes, leads to nanoscopic phase segregation between core and periphery. [3,4] Thus, well-defined dendritic systems that exhibit nematic phase behavior and that are characterized only by orienta-tional ordering and contain functional groups promoting nanophase separation have attracted considerable interest. The opposing forces of the nematic director field, which are attributed to the peripheral mesogens, and the tendency of the dendritic cores to undergo phase separation should lead to a new class of compounds with interesting properties in the liquid-crystalline (LC) state. [5] This structural concept should allow the decoupling of the transition behavior and the ordering of the LC phase from the size of the molecules, which is a long-standing aim of LC polymer research. The materials should additionally be characterized by comparatively low viscosities.The use of carbosilazane cores 1 ± 5, which display an overall threefold symmetry and possess a planar central core, allows the synthesis of microphase-separated systems. [6] The

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Smectogenic dimeric liquid crystals. The preparation and properties of the α,ω-bis(4-n-alkylanilinebenzylidine-4′-oxy)alkanes

Cited by 298 publications

References 29 publications

Synthesis and comparative studies of phase transition behaviour of new dimeric liquid crystals consisting of dimethyluracil and biphenyl cores

Synthesis and comparative studies of phase transition behaviour of new dimeric liquid crystals consisting of dimethyluracil and biphenyl cores

Phase transition studies in mesogenic dimers

Nematic Dendrimers Based on Carbosilazane Cores

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