Structure of molecules by NMR spectroscopy using liquid crystal solvents

Suryaprakash, N.

doi:10.1002/(sici)1099-0534(1998)10:3<167::aid-cmr3>3.0.co;2-v

Cited by 19 publications

(9 citation statements)

References 71 publications

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“…Aiming at treating more complex molecules of lower symmetry, a wide range of weakly ordering liquid crystalline media has been explored over the years [18][19][20][21][22][23]. Among those soluble in organic solvents, the most popular are probably the chiral nematic phases made of synthetic homopolypeptides, namely poly-γ -benzyl-L-glutamate (PBLG), poly-γ -ethyl-L-glutamate (PELG), or poly-ε-carbobenzyloxy-L-lysine (PCBLL), dissolved in helicogenic organic solvents [24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Conformational and Orientational Determination from Dipolar Couplings in a Weakly Ordering Organic-Based Lyotropic and a Strongly Ordering Thermotropic Liquid Crystal

Pietro

Celebre

et al. 2015

Molecular Crystals and Liquid Crystals

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A weakly ordering organic-based lyotropic phase and a strongly ordering nematic liquid crystal have been used as NMR media for a parallel study of the conformation and orientational order of the same solute, trans-stilbene. A careful comparison allows to figure out some interesting conclusions on accessibility and precision of the experimental data and reliability and accuracy of the conformational descriptions into these two kinds of mesophases.

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Section: Introductionmentioning

confidence: 99%

Conformational and Orientational Determination from Dipolar Couplings in a Weakly Ordering Organic-Based Lyotropic and a Strongly Ordering Thermotropic Liquid Crystal

Pietro

Celebre

et al. 2015

Molecular Crystals and Liquid Crystals

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“…In order to control a system, as in quantum information processing [1], this task is critically important, because current optimal control algorithms, such as gradient ascent pulse engineering [2] and strongly modulating pulse [3] algorithms, depend on the full information of the Hamiltonian. Moreover, the Hamiltonian of spin systems provides valuable information for molecular structure analysis [4].…”

Section: Introductionmentioning

confidence: 99%

Hamiltonian Characterization for Dipolar Coupled Spin Systems

Trottier,

Jauregui-Villanueva,

Zhang

2013

Preprint

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Measuring the Hamiltonian of dipolar coupled spin systems is usually a difficult task due to the high complexity of their spectra. Currently, molecules with unknown geometrical structure and low symmetry are extremely tedious or impossible to analyze by sheer spectral fitting. We present a novel method that addresses the problem of spectral analysis, and report experimental results of extracting, by spectral fitting, the parameters of an oriented 6-spin system with very low symmetry in structure, without using a priori knowledge or assumptions on the molecular geometry or order parameters. The advantages of our method are achieved with the use of a new spectral analysis algorithm -NAFONS (Non-Assigned Frequency Optimization of NMR Spectra), and by the use of simplified spectra obtained by transition selective pulses. This new method goes beyond the limit of spectral analysis for dipolar coupled spin systems and is helpful for related fields, such as quantum computation and molecular structure analysis.

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“…Over the years a large body of NMR data on solutes in nematic phases has been accumulated, and a great deal of information about molecular structures has been published. − However, the majority of these structures is based on an incomplete theory in which a “rigid” structure is taken as the starting point and effects of vibrational motion (usually in the harmonic approximation) have been added later on an ad hoc basis. Unfortunately, this approach neglects the interplay that exists between vibrational and reorientational motions.…”

Section: Introductionmentioning

confidence: 99%

Scope and Limitations of Accurate Structure Determination of Solutes Dissolved in Liquid Crystals

Lange¹,

Meerts²,

Weber³

et al. 2010

J. Phys. Chem. A

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The determination of accurate structures of relatively small molecules dissolved in liquid-crystal solvents is no trivial matter. Extensive vibrational corrections to the observed dipolar couplings are required. Vibrational force fields are often available, but the usual harmonic corrections are strictly limited to small-amplitude internal motions. Moreover, the need to also apply anharmonic corrections and to include the elusive vibration-reorientation interaction is problematic and can only be fulfilled for a very limited set of small molecules. In this paper we discuss the implications for the accuracy of the structure of larger molecules for which this information is not available. We discuss the examples of azulene and biphenylene, and set realistic limits on their proton structures, derived from (1)H dipolar couplings extracted from NMR spectra obtained in different liquid-crystal solvents and analyzed with sophisticated evolutionary algorithms.

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Structure of molecules by NMR spectroscopy using liquid crystal solvents

Cited by 19 publications

References 71 publications

Conformational and Orientational Determination from Dipolar Couplings in a Weakly Ordering Organic-Based Lyotropic and a Strongly Ordering Thermotropic Liquid Crystal

Conformational and Orientational Determination from Dipolar Couplings in a Weakly Ordering Organic-Based Lyotropic and a Strongly Ordering Thermotropic Liquid Crystal

Hamiltonian Characterization for Dipolar Coupled Spin Systems

Scope and Limitations of Accurate Structure Determination of Solutes Dissolved in Liquid Crystals

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