Heliconical-layered nanocylinders (HLNCs) – hierarchical self-assembly in a unique B4 phase liquid crystal morphology

Shadpour, Sasan; Nemati, Ahlam; Boyd, Nicola Jane; Li, Lin; Prévôt, Marianne E.; Wakerlin, Samantha L.; Vanegas, Julie P.; Salamończyk, Mirosław; Hegmann, Elda; Zhu, Chenhui; Wilson, Mark R.; Jákli, Antal; Hegmann, Torsten

doi:10.1039/c9mh00089e

Cited by 30 publications

(98 citation statements)

References 38 publications

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“…4i, S12 and S13 †), which can tentatively be attributed to the mean alkyl chain distance (0.44 nm) and the edge-to-edge and face-to-face packing distances of the aromatics (0.56/0.37 nm). This diffraction pattern is similar to those typically recorded for the symmetry broken so crystalline mesophases of bent-core mesogens, helical nano-laments (HNFs), 16,33a helical nano-crystallites (HNCs) 34 and related helical phases, 35 which in some respect can be considered as solvent free gels. 16,36,37 A transition from the LC Cub bi phase to a so crystalline network structure, where the polyaromatic rods and parts of the aliphatic chains assume a crystalline packing, appears likely.…”

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confidence: 80%

Spontaneous mirror symmetry breaking in benzil-based soft crystalline, cubic liquid crystalline and isotropic liquid phases

et al. 2020

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confidence: 80%

Spontaneous mirror symmetry breaking in benzil-based soft crystalline, cubic liquid crystalline and isotropic liquid phases

et al. 2020

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“…[6,7] Only during the past year, we witnessed a rapid expansion of the family of chiral LC phases, as exemplified by the discoveries of helical smectic phases made of achiral bent molecules (SmC TB , analogous to N TB phase) [40][41][42][43] and heliconical cylinder phases. [44] To fully understand how RXS and other advanced methods granted access to unique information on chiral LC phases, we shortly discuss their structures in the following subsections.…”

Section: Progress In Chiral Liquid Crystal Phasesmentioning

confidence: 99%

“…Notably, both chiral and achiral molecules forming complex morphologies have been shown by circular dichroism to exhibit mesoscopic homochirality, originating from structural features at different length scales (packing of molecules within layers or fibers). [44,84,85] Studies of the helical filament phases by standard X-ray methods have revealed their crystalline nature, although the X-ray signals showed characteristic broadening caused by the finite size of the investigated objects. [86] Resonant X-ray studies were also recently carried out, providing additional insight into the nature of the chiral morphology.…”

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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“…[ * ] and Cub bi Ia3 d/I23 [ * ] phases, can obviously be retained after crystallization of the aromatic cores in the optically isotropic crystalline mesophases of compounds 3/ 2 Yn,w here the polyaromatic cores and parts of the alkyl chains assume ac rystalline packing in the networks and the disordered segmentso ft he alkyl chainsf ill the remaining space.T hese crystalline mesophases are in some respect relatedt og els ("solvent free gels"), [43,59,60,62,[64][65][66] thoughdetails of their structures require further investigations. Ac ertain degree of net connectivity is in some cases also retained in the isotropic liquid phases,c onsidered as percolated liquids [67,68] and representing dynamic networks, which become chiral after crossingt he critical network density required fore mergence of chirality synchronization.…”

Section: Discussion Of the Importance Of Network Formation For Chiralmentioning

confidence: 99%

“…[73,74] Figure 11 summarizes the relations between molecular structure and formation of the distinct cubic and accompanying mirror symmetryb roken Iso 1 [ * ] phases gained herein. Overall, this work contributes to the better understanding of the development of networks and spontaneousm irror symmetry breaking in self-assembled systems, including crystalline helical aggregates, [43,[64][65][66][67][68][69][70][71][72][73][74][75] gels, [60,66] LC phases [38,59,60,62,[76][77][78][79] and Figure 11. Summary of the relationsb etween molecular structure, cubic phaset ype,cubic phase stability and mirror symmetry breaking in the LC and isotropic liquid phases.…”

Section: Discussionmentioning

confidence: 99%

Controlling Mirror Symmetry Breaking and Network Formation in Liquid Crystalline Cubic, Isotropic Liquid and Crystalline Phases of Benzil‐Based Polycatenars

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Poppe

Tschierske

2020

Chemistry A European J

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Spontaneousd evelopment of chirality in systems composed of achiral molecules is important for new routes to asymmetricsynthesis, chiral superstructures and materials, as well as for the understanding of the mechanisms of emergence of prebiotic chirality.H erein, it is shown that the 4,4'diphenylbenzil unit is au niversal transiently chiral bent building block for the design of multi-chained (polycatenar) rod-like molecules capable of forming aw idev ariety of helically twisted network structures in the liquid,t he liquid crystalline (LC) and the crystalline state. Single polar substituents at the apex of tricatenar molecules support the formation of the achiral (racemic) cubic double network phase with Ia3 d symmetry and relatively small twist along the networks. The combination of an alkyl chain with fluorine substitution leads to the homogeneously chiral triple network phase with I23 space group, and in addition, provides am irror symmetry broken liquid.R eplacing Fb yC lo rB rf urtheri ncreasest he twist,l eading to as hort pitch doubleg yroid Ia3 d phase, which is achiral again. The effects of the structural variations on the network structures, either leading to achiral phases or chiral conglomerates are analyzed.

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Heliconical-layered nanocylinders (HLNCs) – hierarchical self-assembly in a unique B4 phase liquid crystal morphology

Cited by 30 publications

References 38 publications

Spontaneous mirror symmetry breaking in benzil-based soft crystalline, cubic liquid crystalline and isotropic liquid phases

Spontaneous mirror symmetry breaking in benzil-based soft crystalline, cubic liquid crystalline and isotropic liquid phases

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

Controlling Mirror Symmetry Breaking and Network Formation in Liquid Crystalline Cubic, Isotropic Liquid and Crystalline Phases of Benzil‐Based Polycatenars

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