Organic chiral nano- and microfilaments: types, formation, and template applications

Gowda, Ashwathanarayana; Pathak, Suraj Kumar; Rohaley, Grace A. R.; Acharjee, Gourab; Oprandi, Andrea; Williams, Ryan; Prévôt, Marianne E.; Hegmann, Torsten

doi:10.1039/d3mh01390a

Cited by 6 publications

(3 citation statements)

References 223 publications

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“…This aspect certainly deserves further investigation through electro-optical characterization. Another interesting question to be elucidated is whether the mesoscale undulations observed in our films could be caused by a frustration mechanism similar to that originating saddle splay layer distortion in the so-called helical nanofilament (HNF) phases of BCMs [ 7 , 8 , 46 , 47 ].…”

Section: Discussionmentioning

confidence: 99%

“…However, despite considerable experimental effort, the biaxial N phase has remained elusive, with no undisputable evidence reported until now for low-molecular-weight calamitic LCs [ 3 , 4 ]. Over the last two decades, bent-core mesogens (BCMs), a class of compounds featuring a kinked aromatic core between two terminal aliphatic tails, have attracted considerable interest for the formation of a variety of exotic mesophases and self-assembled supramolecular structures [ 5 , 6 , 7 , 8 ], as well as for the exhibition of a possibly biaxial N phase [ 5 , 9 , 10 , 11 ]. Although the occurrence of spontaneous macroscopic biaxiality in nematic BCMs has been questioned, strong experimental evidence suggests the presence of local biaxial (and possibly polar) order within nanosized clusters of stratified molecules (known as cybotactic groups) which permeate the N phase.…”

Section: Introductionmentioning

confidence: 99%

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Macroscopic Biaxial Order in Multilayer Films of Bent-Core Liquid Crystals Deposited by Combined Langmuir–Blodgett/Langmuir–Schaefer Technique

Vita,

Adamo,

Campana

et al. 2024

Nanomaterials

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Bent-core liquid crystals, a class of mesogenic compounds with non-linear molecular structures, are well known for their unconventional mesophases, characterized by complex molecular (and supramolecular) ordering and often featuring biaxial and polar properties. In the nematic phase, their unique behavior is manifested in the formation of nano-sized biaxial clusters of layered molecules (cybotactic groups). While this prompted their consideration in the quest for nematic biaxiality, experimental evidence indicates that the cybotactic order is only short-ranged and that the nematic phase is macroscopically uniaxial. By combining atomic force microscopy, neutron reflectivity and wide-angle grazing-incidence X-ray scattering, here, we demonstrate that multilayer films of a bent-core nematic, deposited on silicon by a combined Langmuir–Blodgett and Langmuir–Schaefer approach, exhibit macroscopic in-plane ordering, with the long molecular axis tilted with respect to the sample surface and the short molecular axis (i.e., the apex bisector) aligned along the film compression direction. We thus propose the use of Langmuir films as an effective way to study and control the complex anchoring properties of bent-core liquid crystals.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Macroscopic Biaxial Order in Multilayer Films of Bent-Core Liquid Crystals Deposited by Combined Langmuir–Blodgett/Langmuir–Schaefer Technique

Vita,

Adamo,

Campana

et al. 2024

Nanomaterials

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“…Typically, bent-shaped liquid crystalline molecules are composed of three units: an angular central core, two linear rigid arms, and terminal chains [ 55 , 56 , 57 , 58 , 59 , 60 , 61 ]. Bent-core dimers with a flexible spacer consisting of an odd number of methylene groups are a kind of typical bent-core liquid crystal which are usually synthesized by using rod-shaped liquid crystals [ 62 ]. Lin et al explored the flexoelectric-effect-induced switching mechanism of positive dielectric cholesteric liquid crystals doped with the bent-core liquid crystal dimer CB7CB.…”

Section: Electrically Driven Multi-stable Modes Of Cholesteric Liquid...mentioning

confidence: 99%

Research Progress of Electrically Driven Multi-Stable Cholesteric Liquid Crystals

Wang,

Hu,

et al. 2023

Materials

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Electrically driven multi-stable cholesteric liquid crystals can be used to adjust the transmittance of incident light. Compared with the traditional liquid crystal optical devices, the multi-stable devices only apply an electric field during switching and do not require a continuous electric field to maintain the various optical states of the device. Therefore, the multi-stable devices have low energy consumption and have become a research focus for researchers. However, the multi-stable devices still have shortcomings before practical application, such as contrast, switching time, and mechanical strength. In this article, the latest research progress on electrically driven multi-stable cholesteric liquid crystals is reviewed, including electrically driven multi-stable modes, performance optimization, and applications. Finally, the challenges and opportunities of electrically driven multi-stable cholesteric liquid crystals are discussed in anticipation of contributing to the development of multi-stable liquid crystal devices.

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Multifaceted regulation of chiroptical properties and self‐assembly behaviors of chiral fluorescent polymers

He,

Zhang,

et al. 2024

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The multifaceted regulation of the chiroptical properties and self‐assembly behaviors of chiral fluorescent polymers is of great significance yet remains challenging to achieve. Herein, a series of novel salen‐based chiral fluorescent polymers with aggregation‐induced emission and varied substitution manners were facilely and efficiently synthesized. Multiple factors were systematically investigated on the chiroptical properties and self‐assembly performance of these polymers, which include molecular structures, solvent environments, metal coordination, and liquid crystal (LC) assemblies. Sutle change in the solvent composition can lead to diverse assembly morphologies of all these chiral polymers, from single‐handed helical fibers, helical toroids or loops, to spherical structures, consequently leading to an aggregation‐reduced circular dichroism (CD) phenomenon. The polymers bearing salen units show highly selective and reversible coordination with Zn2+ and can also induce multiple responses in the absorption, luminescence, CD, and circularly polarized luminescence (CPL) of these chiral fluorescent polymers via a coordination‐ and dissociation‐initiated self‐assembly tuning. Furthermore, a small amount of the chiral fluorescent polymer in can induce achiral nematic 4‐cyano‐4′‐n‐pentylbiphenyl (5CB) to form ordered chiral nematic LC phase with significant improvement in their CD and CPL signal. The absolute absorption and luminescent dissymmetry factors of the resulting supramolecular assemblies can reach the order of 10−1.

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Organic chiral nano- and microfilaments: types, formation, and template applications

Abstract: Chiral filaments are omnipresent in nature and our daily lives. This review gives an overview of nano- and microfilaments, delineates formation modes based on the concept of intra- or interlayer misfits, and shows examples of template applications.

Cited by 6 publications

References 223 publications

Macroscopic Biaxial Order in Multilayer Films of Bent-Core Liquid Crystals Deposited by Combined Langmuir–Blodgett/Langmuir–Schaefer Technique

Macroscopic Biaxial Order in Multilayer Films of Bent-Core Liquid Crystals Deposited by Combined Langmuir–Blodgett/Langmuir–Schaefer Technique

Research Progress of Electrically Driven Multi-Stable Cholesteric Liquid Crystals

Multifaceted regulation of chiroptical properties and self‐assembly behaviors of chiral fluorescent polymers

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