Liquid Crystals as Solvents for Spectroscopic, Chemical Reaction, and Gas Chromatographic Applications

Leigh, William J.; Workentin, Mark S.

doi:10.1002/9783527619276.ch9da

Cited by 5 publications

(2 citation statements)

References 513 publications

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“…NMR in thermotropic (achiral) liquid crystals has been first used to investigate the influence of the solvent anisotropy on the fate of the reaction. 37 Another advantage of oriented media (chiral or not) is the use of anisotropic NMR interactions to obtain new insights into the progress of a reaction. In particular, it has been shown that 2 H-{ 1 H} NMR in CLCs could be advantageously employed to monitor the conversion between deuterated enantiomers.…”

Section: Chemical Reaction Monitoringmentioning

confidence: 99%

Combining Fast 2D NMR Methods and Oriented Media

Lesot

Lafon

2023

Fast 2D Solution-State NMR

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NMR in oriented samples (anisotropic solvents) offers access to informative residual order-dependent NMR interactions, including chemical shift anisotropies (RCSAs), dipolar couplings (RDCs), and quadrupolar couplings (RQCs), while preserving high spectral resolution. The analysis of these spectra often requires two-dimensional (2D) NMR experiments due to these additional anisotropic interactions. In addition, accelerated 2D NMR experiments can be essential for particular investigations, including in situ monitoring of chemical reactions or the observation of dilute isotopes, e.g. 2H and 13C, since the stability of oriented phases is limited in time and the magnetic field, B0, can drift in the absence of 2H lock. We provide here an overview of these fast 2D NMR experiments in anisotropic media. These developments have benefited from those for isotropic solutions, such as fast pulsing techniques enhancing the polarization, sparse sampling, Hadamard spectroscopy or spatial encoding. Nevertheless, fast 2D NMR in mesophases and solids present particular challenges, since these 2D spectra usually display lower signal-to-noise ratios, non-Lorentzian lineshapes, lower spectral resolution and wider spectral widths than their counterparts for isotropic solutions. We discuss here the advantages and limitations of various approaches, which have been applied for the fast 2D NMR spectra of mesophases and solids.

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Section: Chemical Reaction Monitoringmentioning

confidence: 99%

Combining Fast 2D NMR Methods and Oriented Media

Lesot

Lafon

2023

Fast 2D Solution-State NMR

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“…are generally unable to realize ideal selectivity, although their relatively loose structures are promising for the promotion of the in situ reaction. In attempts to overcome these problems, several groups have employed LCs as media to control chemical reactions [ 24 , 49 , 50 ]; among mesophase aggregates, thermotropic LCs are regarded as one of the most structurally ordered classes, which should be advantageous for the control of organic transformations.…”

Section: Tailored Reaction Mediamentioning

confidence: 99%

Organic Zeolite Analogues Based on Multi-Component Liquid Crystals: Recognition and Transformation of Molecules within Constrained Environments

Ishida

2011

Materials

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In liquid crystals (LCs), molecules are confined in peculiar environments, where ordered alignment and certain mobility are realized at the same time. Considering these characteristics, the idea of “controlling molecular events within LC media” seems reasonable. As a suitable system for investigating this challenge, we have recently developed a new class of ionic LCs; the salts of amphiphilic carboxylic acids with 2-amino alcohols, or those of carboxylic acids with amphiphilic 2-amino alcohols, have a strong tendency to exhibit thermotropic LC phases. Because of the noncovalent nature of the interaction between molecules, one of the two components can easily be exchanged with, or transformed into, another molecule, without distorting the original LC architecture. In addition, both components are common organic molecules, and a variety of compounds are easily available. Taking advantage of these characteristics, we have succeeded in applying two-component LCs as chiral media for molecular recognition and reactions. This review presents an overview of our recent studies, together with notable reports related to this field.

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Anisotropic One‐dimensional/Two‐dimensionalNMRin Molecular Analysis

Lesot

Gil

2023

Two‐Dimensional (2D) NMR Methods

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Liquid Crystals as Solvents for Spectroscopic, Chemical Reaction, and Gas Chromatographic Applications

Cited by 5 publications

References 513 publications

Combining Fast 2D NMR Methods and Oriented Media

Combining Fast 2D NMR Methods and Oriented Media

Organic Zeolite Analogues Based on Multi-Component Liquid Crystals: Recognition and Transformation of Molecules within Constrained Environments

Anisotropic One‐dimensional/Two‐dimensionalNMRin Molecular Analysis

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