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

Journal Article · Tue Jul 07 04:00:00 EDT 2015 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4923253· OSTI ID:22490861

Weber, Adrian C. J., ^[1]; Lange, Cornelis A. de, ^[2]; Muccioli, Luca; Pizzirusso, Antonio; Zannoni, Claudio ^[3]

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1. Chemistry Department, Brandon University, 270-18th Street, Brandon, Manitoba R7A 6A9 (Canada)
2. Atomic, Molecular and Laser Physics, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands)
3. Dipartimento di Chimica Industriale “Toso Montanari,” Università di Bologna and INSTM, viale Risorgimento 4, 40136 Bologna (Italy)

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.

• OSTI ID: 22490861
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 1 Vol. 143; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
COUPLINGS
HEXANE
LIQUID CRYSTALS
MOLECULAR DYNAMICS METHOD
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
PROTONS
SIGNALS
SIMULATION