Optical Acetone Vapor Sensors Based on Chiral Nematic Liquid Crystals and Reactive Chiral Dopants

Cachelin, Pascal; Green, Joshua P.; Peijs, Ton; Heeney, Martin; Bastiaansen, Cees W. M.

doi:10.1002/adom.201500549

Cited by 30 publications

(23 citation statements)

References 33 publications

(29 reference statements)

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“…Another approach to using chiral dopants is based on the principle that, upon reaction with a specific analyte, the dopant will respond with either a chemical or a supramolecular way, leading to changes in the reflected color. [ 99,160 ] For example, Cachelin et al [ 161 ] have recently developed a time‐integrating sensor, which can serve as a chemical dosimeter by measuring the total exposure to an analyte over a given time frame. In their work, they described an acetone vapor detection system, based on a film of E7 doped with tetraaryl‐1,3‐dioxolane (TADDOL)–phenylhydrazine complex.…”

Section: Functional Liquid Crystal Materialsmentioning

confidence: 99%

Seeing the Unseen: The Role of Liquid Crystals in Gas‐Sensing Technologies

Esteves

Ramou

Porteira

et al. 2020

Advanced Optical Materials

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Fast, real‐time detection of gases and volatile organic compounds (VOCs) is an emerging research field relevant to most aspects of modern society, from households to health facilities, industrial units, and military environments. Sensor features such as high sensitivity, selectivity, fast response, and low energy consumption are essential. Liquid crystal (LC)‐based sensors fulfill these requirements due to their chemical diversity, inherent self‐assembly potential, and reversible molecular order, resulting in tunable stimuli‐responsive soft materials. Sensing platforms utilizing thermotropic uniaxial systems—nematic and smectic—that exploit not only interfacial phenomena, but also changes in the LC bulk, are demonstrated. Special focus is given to the different interaction mechanisms and tuned selectivity toward gas and VOC analytes. Furthermore, the different experimental methods used to transduce the presence of chemical analytes into macroscopic signals are discussed and detailed examples are provided. Future perspectives and trends in the field, in particular the opportunities for LC‐based advanced materials in artificial olfaction, are also discussed.

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Section: Functional Liquid Crystal Materialsmentioning

confidence: 99%

Seeing the Unseen: The Role of Liquid Crystals in Gas‐Sensing Technologies

Esteves

Ramou

Porteira

et al. 2020

Advanced Optical Materials

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“…Liquid crystals (LCs), which combine key properties of crystalline solids (long‐range order) and isotropic liquids (molecular mobility), are a promising class of chemoresponsive materials because the orientations of molecules (mesogens) within LCs, termed the director, can be changed by subtle interactions between mesogens and chemical functional groups presented at surfaces . For example, past studies have shown that mesogens with specific functional groups (for example, nitrile or pyrimidine) can bind to metal cations presented at surfaces, and that competitive binding of chemical species such as organophosphonates can disrupt those binding interactions to trigger ordering transitions in the LC . The ordering transitions are visible to the naked eye or can be quantified using simple optical methods.…”

Section: Methodsmentioning

confidence: 99%

Redox‐Triggered Orientational Responses of Liquid Crystals to Chlorine Gas

et al. 2018

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Surface‐supported liquid crystals (LCs) that exhibit orientational and thus optical responses upon exposure to ppb concentrations of Cl2 gas are reported. Computations identified Mn cations as candidate surface binding sites that undergo redox‐triggered changes in the strength of binding to nitrogen‐based LCs upon exposure to Cl2 gas. Guided by these predictions, μm‐thick films of nitrile‐ or pyridine‐containing LCs were prepared on surfaces decorated with Mn2+ binding sites as perchlorate salts. Following exposure to Cl2, formation of Mn4+ (in the form of MnO2 microparticles) was confirmed and an accompanying change in the orientation and optical appearance of the supported LC films was measured. In unoptimized systems, the LC orientational transitions provided the sensitivity and response times needed for monitoring human exposure to Cl2 gas. The response was also selective to Cl2 over other oxidizing agents such as air or NO2 and other chemical targets such as organophosphonates.

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“…На их основе разрабатываются гибкие магниты [13], светочувствительные наноструктуры [14], хирооптические молекулярные переключатели [15][16][17] и микролинзы для биомиметических оптических систем [18]. В работах [19,20] показана возможность создания высокочувствительных и селективных сенсоров для обнаружения газов на основе ЖК и химически активных хиральных допантов. Существенный практический интерес может вызвать использование фоточувствительных ЖК допантов в органических солнечных ячейках [21].…”

Section: индуцированные спиральные жидкокристаллические фазыunclassified

Mechanisms of Chiral Transfer in Optically Active Dopant – Nematic Liquid Crystal Systems

Burmistrov¹,

Aleksandriiskii²,

Новиков³

et al. 2020

Liq. Cryst. and their Appl.

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Induction of helical mesophases by incorporating chiral dopants into the nematics matrix is the promising modern trends in the chemistry of liquid crystals. This process is associated with a unique phenomenon - an amplification of chirality in liquid-crystalline phases, which ensures the detection of enantiomers by their chiral induction, much more sensitive than other methods. The relevance of this approach is due to the need to create perspective electro-optical devices operating with ultra-low control voltages based on twist effects, chromatographic stationary phases with high chiral selectivity, flexible magnets, photo-sensitive nanostructures, and other smart LC materials. The successful solution of these problems is impossible without experimental research and theoretical comprehension of the mechanisms of third level chiral transfer optically active dopant – nematic liquid crystal. In the last decade, a large number of works have appeared on the solution of these problems. This review is devoted to a generalization of the experimental results and a theoretical description of the transfer of molecular chirality to orientationally ordered systems with the participation of both chiral molecular substituents with an asymmetric carbon atom and planar or quasi-planar fragments chirally distorted relative to each other. The stereochemical aspects of induction associated with the structural correspondences of the dopant and nematic liquid crystal, as well as the main classes of optically active additives, are discussed. Application of metal complexes, both Werner and macroheterocyclic, are presented. Special attention is paid to the results of the mechanisms study of chiral transfer due to various intermolecular interactions: hydrogen bonding, axial coordination, and the formation of inclusion compounds. The high efficiency of induction of spiral mesophases has been demonstrated with a combination of different self-assembly mechanisms in liquid crystal - chiral additive systems.

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Optical Acetone Vapor Sensors Based on Chiral Nematic Liquid Crystals and Reactive Chiral Dopants

Cited by 30 publications

References 33 publications

Seeing the Unseen: The Role of Liquid Crystals in Gas‐Sensing Technologies

Seeing the Unseen: The Role of Liquid Crystals in Gas‐Sensing Technologies

Redox‐Triggered Orientational Responses of Liquid Crystals to Chlorine Gas

Mechanisms of Chiral Transfer in Optically Active Dopant – Nematic Liquid Crystal Systems

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