Optic and electro-optic investigations on SmQ, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si34.gif" overflow="scroll"><mml:msubsup><mml:mrow><mml:mi>SmC</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">A</mml:mi></mml:mrow><mml:mrow><mml:mo>*</mml:mo></mml:mrow></mml:msubsup></mml:math> and L phases in highly chiral compounds

Manai, M.; Gharbi, A.; Marcerou, J. P.; Nguyen, H. T.; Rouillon, J. C.

doi:10.1016/j.physb.2005.07.013

Cited by 11 publications

(4 citation statements)

References 38 publications

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“…Helical and polar structures have been known to appear as a result of a chiral effect: the helical structures are observed in the chiral nematic, blue, and twist grain boundary liquid crystal phases, and the polar structures, with the helical structures in some cases, observed in the ferroelectric, antiferroelectric, and related chiral liquid crystal phases. In our previous studies, a dichiral azobenzene compound (AZO-PP, Figure ) was designed and prepared, , and was found to exhibit two SmQ − phases that are known to possess three-dimensional (3D) tetragonal liquid crystal structures. , In this Letter, on the basis of the detailed investigation on the effect of the optical purity of AZO-PP, a new type of chiral effect that induces the optical anisotropy in the 3D liquid crystal phase is for the first time reported.…”

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confidence: 89%

Novel Chiral Effect That Produces the Anisotropy in 3D Structured Soft Material: Chirality-Driven Cubic−Tetragonal Liquid Crystal Phase Transition

et al. 2009

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The effect of chirality on the liquid crystal organization has been systematically investigated between (S,S)- and (R,R)-isomers of a dichiral azobenzene compound. The racemic mixture was found to show the cubic phase (Im3m), indicating that the studied compound shows the cubic structure without the effect of chirality. However, with increasing optical purity of the racemic mixture, the cubic (Im3m) structure changes into the tetragonal phases (I422 and I4(1)22), which have been known as the SmQ phases, via a chiral cubic phase (I432). This is the first example of "chirality-driven" cubic-tetragonal structural change observed in liquid crystal systems, which is experimental evidence showing the novel type of chiral effect that produces the anisotropy in the structures of soft materials. The emergence of the anisotropy, i.e., the cubic-tetragonal phase transformation, is also induced by means of photoinduced phase transition of the SmQ phases based on cis-trans photoisomerization of the azobenzene compounds.

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confidence: 89%

Novel Chiral Effect That Produces the Anisotropy in 3D Structured Soft Material: Chirality-Driven Cubic−Tetragonal Liquid Crystal Phase Transition

et al. 2009

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“…From a molecular structure viewpoint, the characteristics of the chiral part of the azo‐dichiral molecule are important because all known compounds exhibiting the SmQ phase typically have the same chiral part structure,22–24,30–34 such as that of compounds 17 (Fig. 2), 18 , and 19 (Fig.…”

Section: Discussionmentioning

confidence: 99%

Toward rational design of complex nanostructured liquid crystals

Yoneya

2011

The Chemical Record

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An analogy of block copolymer micro-segregation as a low-molecular weight nanostructured liquid crystal (LC) was tested with recently found columnar and cubic phase-forming LC molecules, to clarify the broader applicability of the analogy as a molecular design principle. We found that the copolymer analogy principle also works well for new micellar cubic phase-forming molecules. For bicontinuous cubic phase-forming 1,2-bis(4'-n-alkoxybenzoyl)hydrazines (BABH-n) compounds that cover a much broader core fraction range than that predicted by the copolymer analogy, we propose hierarchical preferential orientation as an additional mechanism for their cubic range broadening. For azo-dichiral molecules that also do not fit with the above principle, we propose chiral segregation as an alternative origin for their cubic phase formation.

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“…The density (packing) differences in Figure could be related to the chirality-dependent molecular conformations. The characteristics of the chiral part of the M7BBM7 molecule would be important since all known SmQ-phase-showing compounds commonly have the same chiral part structure. – …”

Section: Discussionmentioning

confidence: 99%

“…Smectic Q (SmQ) phases , are also considered as chirality-originated 3D-structured LC phases since the SmQ phases are very sensitive to optical purities and are lost with low chiral fractions . Only a limited number of compounds have been known to exhibit the SmQ phases, but new compounds have been reported recently. – Compared with the BPs, the SmQ phases have a small unit cell length (∼10 nm) and tetragonal (for T*1, T*2, and T*3 SmQ subphases) or hexagonal (for the H* subphase) symmetry . The unit cell length of a SmQ phase is similar to that of yet another 3D-structured LC phase, the cubic (Cub) phase, although the origin of Cub phase formation is considered to be different, that is, nanosegregation .…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulation Study of the Influence of Chirality on the Stability of the Smectic Q Liquid Crystal Phase

et al. 2008

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The structure of smectic Q (SmQ) liquid crystal phase consisting of a dichiral molecule, called M7BBM7, was studied by submicrosecond molecular dynamics (MD) simulation. A detailed atomic model was used to study the stability of a model SmQ structure proposed by Levelut et al. (Levelut, A.-M.; Hallouin, E.; Bennemenn, D.; Heppke, G.; Lotzsch, D. J. Phys. II 1997, 7, 981) and its difference between (S,S)-, (S,R)-M7BBM7 and racemic mixture systems. Negative values of the fourth-rank orientational order parameter (), which characterize the model SmQ structure, were stably kept up to a 100 ns MD run only in the (S,S)-M7BBM7 system and lost in the other systems. The results correspond well to the marked chiral sensitivity in real systems where only the (S,S)-M7BBM7 system (among the three above-mentioned systems) shows the SmQ phase. Our simulation results imply that the asymmetric intramolecular potentials and resultant chirality-dependent molecular conformations are primarily responsible for keeping the negative values of and the model SmQ structure.

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Optic and electro-optic investigations on SmQ, SmCA* and L phases in highly chiral compounds

Cited by 11 publications

References 38 publications

Novel Chiral Effect That Produces the Anisotropy in 3D Structured Soft Material: Chirality-Driven Cubic−Tetragonal Liquid Crystal Phase Transition

Novel Chiral Effect That Produces the Anisotropy in 3D Structured Soft Material: Chirality-Driven Cubic−Tetragonal Liquid Crystal Phase Transition

Toward rational design of complex nanostructured liquid crystals

Molecular Dynamics Simulation Study of the Influence of Chirality on the Stability of the Smectic Q Liquid Crystal Phase

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