An unusual type of polymorphism in a liquid crystal

Li, Lin; Salamończyk, Mirosław; Shadpour, Sasan; Zhu, Chenhui; Jákli, Antal; Hegmann, Torsten

doi:10.1038/s41467-018-03160-9

Cited by 42 publications

(79 citation statements)

References 28 publications

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“…Interestingly, the HNF phase is the only phase observed on cooling. On heating, however, an additional phase is formed in an ≈14 °C temperature interval above the HNF phase, which is characterized by thin‐film textures typically observed for oblique columnar (Col ob ) phases (Figure b) . DSC measurements performed for both compounds, ( m R , p S )‐ 5 and ( m S , p R )‐ 5 , performed at the same heating/cooling rate (5 °C min −1 , see Figure S4 in the Supporting Information), confirm the number of phase transitions on heating and cooling, respectively.…”

Section: Resultssupporting

confidence: 52%

“…The synthetic approach for the new compounds ( m R , p S )‐ 5 and ( m S , p R )‐ 5 (Figure ) was described earlier, and involved the stepwise deprotection and esterification of mono‐tetrahydropyranyl (THP)–mono‐ tert ‐butyldimethylsilyl (TBDMS)‐protected 3,4′‐dihydroxybiphenyl, which was synthesized by a Suzuki coupling reaction (for the synthesis scheme and characterization data, see Scheme S1 as well as Figures S1 and S2 in the Supporting Information).…”

Section: Methodsmentioning

confidence: 99%

“…Upon rapid cooling, we discovered a unique new polymorph for B4 phase BCLCs, which we termed helical microfilaments (HµFs) based on the much larger dimensions of the helical building blocks. Upon slow cooling, however, an oblique columnar (Col ob ) phase was formed by these materials …”

Section: Introductionmentioning

confidence: 99%

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Missing Link between Helical Nano‐ and Microfilaments in B4 Phase Bent‐Core Liquid Crystals, and Deciphering which Chiral Center Controls the Filament Handedness

Shadpour

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Salamończyk

et al. 2019

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The range of possible morphologies for bent‐core B4 phase liquid crystals has recently expanded from helical nanofilaments (HNFs) and modulated HNFs to dual modulated HNFs, helical microfilaments, and heliconical‐layered nanocylinders. These new morphologies are observed when one or both aliphatic side chains contain a chiral center. Here, the following questions are addressed: which of these two chiral centers controls the handedness (helicity) and which morphology of the nanofilaments is formed by bent‐core liquid crystals with tris‐biphenyl diester core flanked by two chiral 2‐octyloxy side chains? The combined results reveal that the longer arm of these nonsymmetric bent‐core liquid crystals controls the handedness of the resulting dual modulated HNFs. These derivatives with opposite configuration of the two chiral side chains now feature twice as large dimensions compared to the homochiral derivatives with identical configuration. These results are supported by density functional theory calculations and stochastic dynamic atomistic simulations, which reveal that the relative difference between the para‐ and meta‐sides of the described series of compounds drives the variation in morphology. Finally, X‐ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) data also uncover the new morphology for B4 phases featuring p2/m symmetry within the filaments and less pronounced crystalline character.

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Section: Resultssupporting

confidence: 52%

Section: Methodsmentioning

confidence: 99%

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Missing Link between Helical Nano‐ and Microfilaments in B4 Phase Bent‐Core Liquid Crystals, and Deciphering which Chiral Center Controls the Filament Handedness

Shadpour

Nemati

Salamończyk

et al. 2019

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“…[7,68] A close relationship between HNF and DC phases was recently highlighted by showing that a spatially confined sample can exhibit both morphologies, depending solely on the diameter of the channels into which the material was introduced. [69] Since then, several groups reported use of FFTEM, low dose thin film TEM, [70] SEM, [71] and AFM [65,72] techniques in the investigation of the structure of supramolecular assemblies of bent and oligomeric molecules (Figure 3b-d), leading to a quickly growing number of reports on the identification of related phases. It was found that helical nanofilament phases may exhibit either very short (helical nanocrystallite phase, HNC, Figure 3a), [73] or much longer fibers (helical microfilament phase, HµF).…”

Section: Liquid Crystals With Chiral Morphologiesmentioning

confidence: 99%

Chirality of Liquid Crystals Formed from Achiral Molecules Revealed by Resonant X‐Ray Scattering

et al. 2020

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effect is also responsible for some "biological recognition" processes, including, for example, our physiological response to odor or taste of opposite enantiomeric species. Although chiral interactions have been broadly studied, the mechanism that leads to single handedness in our world is still under discussion. For example, Viedma [1] showed that deracemization in the solid state, coupled with flexibility of transforming one enantiomeric form into another in the liquid state, may lead to chirality synchronization, that is, in a system that starts from a mixture of racemic crystals, a homochiral end state can be obtained. Similarly, crystallization combined with reversible organic reactions, have been reported to transform initially achiral reactants into an enantiopure solid. [2] Whether the spontaneous formation of a homochiral state from a racemic mixture or achiral molecules can be observed in a fluid phase, is still uncertain. In general, in racemic systems lacking long range positional correlations, the chirodiastaltic forces are probably too weak to achieve spontaneous deracemization and (through amplification) enantiomeric excess. Also, in the liquid crystal (LC) state with only orientational order (nematic phase, N), spontaneous deracemization has not been observed so far, since rod-like molecules forming the N phase have freedom to rotate around their long axes, and thus the chiral discrimination effect is reduced. [3] Only few examples have been reported in which chiral discrimination was found to strongly affect nematic phase stability, but not lead to deracemization. [4] There is, however, a particularly interesting group of achiral mesogenic molecules with (constitutional or conformational) bent geometry, for which rotation is strongly hindered and therefore local interactions between neighboring molecules are expected to be much stronger than those in rod-like molecules. In fact, bent molecules have been shown to spontaneously form structurally chiral domains through chirality synchronization in the isotropic liquid [5] and LC [6,7] phases. Thus, further exploration of chirality in soft systems, such as LCs, may have high relevance toward better understanding the origin of life and be transformative for various technologies relying on chirality in soft matter systems. Testing chirality in soft matter systems (liquid crystals and solid crystals) is not always trivial. The most commonly used tools are optical methods focusing on measurements of optical activity (i.e., the ability of matter to rotate the polarization

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“…Polymorphism of liquid crystals of a bent-core-type molecule controlled solely by cooling speed. [86] This research bridges DNA origami technology with a high programmable capability of unit structure and chirality-controlled materials and colloidal science, which would have important contributions in DNA-based nanoarchitectonics. [93] In soft and flexible liquid-crystalline materials, factors to induce chirality in entire materials are not limited in the range of directly interacting vicinities.…”

Section: Chirality In Liquid Crystalsmentioning

confidence: 99%

Supramolecular Chiral Nanoarchitectonics

et al. 2020

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of well-considered materials designs. [5] Small structural differences in component molecules are often capable of producing materials with totally different properties through organic syntheses, [6] supramolecular chemistry, [7] and materials processing. [8] Therefore, molecular designs for materials production can be regarded as the most important issue in science and technology in current society. Amongst the many possibilities in molecular design for materials production, exploration of molecular functions and material properties on the basis of chirality controls would be a scientifically elegant approach. With identical elemental compositions and functional groups, but different configurations of these identical groups, functions such as chiroptical properties and chiral separations can be created. [9] Another important fact for chiral controls in molecular and materials science is the unavoidable deep relationship of chiral substances with biological activities. [10] Biomolecules are basically made of chiral components such as amino acids and saccharides. Therefore, molecular designs for biomedical drugs and bioactive materials must be produced upon critical control of their chirality. Due to the scientifically elegant approaches and biological importance, molecular sciences and materials technologies incorporating chirality continuously attract attention of scientists ranging from the fundamentals of the chirality of molecules and materials to bio-related applications. These research efforts spread into a wide range of scientific fields including basic physical chemistry, [11] chirality-controlled catalysis and synthesis, [12] chiral materials, [13] analyses of chiral structures, [14] chiral recognition, [15] chiral separation, [16] chiral plasmons and optics, [17] chiral drugs, [18] and biomedical related chiral sciences. [19] Among the broad interests of chirality research, the recent hot trends of chirality related sciences are probably studies on chirality-based supramolecular chemistry and materials science upon the self-assembly of chiral molecular components [20] and achiral building blocks. [21] Enhancement of chiral effects and the creation of chirality are sometimes results of supramolecular organizations with chiral molecular units and even with achiral components. These systems are regarded as elegant examples of the emerging concept of nanoarchitectonics (Figure 1), [22] because control of simple molecular configurations can lead to the creation of such a wide variety of functional materials. The nanoarchitectonics concept was originally proposed by Aono and co-workers [23] as methodology to create functional materials from nanosized components through the combined Exploration of molecular functions and material properties based on the control of chirality would be a scientifically elegant approach. Here, the fabrication and function of chiral-featured materials from both chiral and achiral components using a supramolecular nanoarchitectonics concept are discussed. The contents are classified...

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An unusual type of polymorphism in a liquid crystal

Cited by 42 publications

References 28 publications

Missing Link between Helical Nano‐ and Microfilaments in B4 Phase Bent‐Core Liquid Crystals, and Deciphering which Chiral Center Controls the Filament Handedness

Missing Link between Helical Nano‐ and Microfilaments in B4 Phase Bent‐Core Liquid Crystals, and Deciphering which Chiral Center Controls the Filament Handedness

Chirality of Liquid Crystals Formed from Achiral Molecules Revealed by Resonant X‐Ray Scattering

Supramolecular Chiral Nanoarchitectonics

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