Communication: Molecular dynamics and 1H NMR of n -hexane in liquid crystals

The NMR spectrum of n-hexane orientationally ordered in the nematic liquid crystal ZLI-1132 is analysed using covariance matrix adaptation evolution strategy (CMA-ES). The spectrum contains over 150 000 transitions, with many sharp features appearing above a broad, underlying background signal that...

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Bibliographic Details
Published in:The Journal of chemical physics 2015-07, Vol.143 (1)
Main Authors: Weber, Adrian C. J., Burnell, E. Elliott, Meerts, W. Leo, de Lange, Cornelis A., Dong, Ronald Y., Muccioli, Luca, Pizzirusso, Antonio, Zannoni, Claudio
Format: Article
Language:English
Subjects:
Biological evolution
Chemical industry
Computer simulation
Couplings
Covariance matrix
Crystal structure
Deuteration
Liquid crystals
Molecular dynamics
Nematic crystals
NMR
Nuclear magnetic resonance
Physics
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Summary:The NMR spectrum of n-hexane orientationally ordered in the nematic liquid crystal ZLI-1132 is analysed using covariance matrix adaptation evolution strategy (CMA-ES). The spectrum contains over 150 000 transitions, with many sharp features appearing above a broad, underlying background signal that results from the plethora of overlapping transitions from the n-hexane as well as from the liquid crystal. The CMA-ES requires initial search ranges for NMR spectral parameters, notably the direct dipolar couplings. Several sets of such ranges were utilized, including three from MD simulations and others from the modified chord model that is specifically designed to predict hydrocarbon-chain dipolar couplings. In the end, only inaccurate dipolar couplings from an earlier study utilizing proton-proton double quantum 2D-NMR techniques on partially deuterated n-hexane provided the necessary estimates. The precise set of dipolar couplings obtained can now be used to investigate conformational averaging of n-hexane in a nematic environment.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.4923253