Methyl group dynamics in glassy, polycrystalline, and liquid coenzyme Q(10) studied by quasielastic neutron scattering

Journal article


Publication Details

Author(s): Smuda C, Busch S, Wagner B, Unruh T
Journal: Journal of Chemical Physics
Publisher: AMER INST PHYSICS
Publication year: 2008
Volume: 129
Journal issue: 7
ISSN: 0021-9606


Abstract


The methyl group rotation of coenzyme Q(10) confined in nanosized droplets was studied using quasielastic neutron scattering (QENS). Q(10) as an oligoisoprene derivative with ten isoprene units can easily be supercooled in nanodroplets. Fixed window scans and QENS spectra at several temperatures of glassy Q(10) were recorded to study the methyl group rotation which can be described by a logarithmic Gaussian distribution of hopping rates for temperatures below the glass transition temperature (T(g)approximate to 200 K). A mean activation energy of 4.8 kJ/mol with a distribution width of 2.1 kJ/mol was obtained from the evaluation of the QENS spectra. A corresponding analysis of a fixed window scan yielded an average activation energy of 5.1 kJ/mol with a distribution width of 1.8 kJ/mol. The results are compared and discussed with those of chain deuterated polyisoprene-d(5). For polycrystalline Q(10), the QENS spectra could be described by the same model yielding a similar average activation energy as found for glassy Q(10). However, no temperature dependence of the distribution width was observed. Based on the performed low-temperature measurements, the correlation times for the methyl group rotation were extrapolated to temperatures of liquid Q(10). The complex dynamics of liquid Q(10) could be described by a model yielding an apparent diffusion coefficient, the jump rate of the methyl groups, as well as an overall molecular rotational diffusion coefficient. The correlation times of the methyl group rotation in liquid Q(10) at a given temperature T(0) coincide with values determined in the glassy phase and extrapolated to T(0). (C) 2008 American Institute of Physics.



FAU Authors / FAU Editors

Unruh, Tobias Prof. Dr.
Professur für Nanomaterialcharakterisierung (Streumethoden)


External institutions
Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung GmbH (HZG)
Technische Universität München (TUM)


How to cite

APA:
Smuda, C., Busch, S., Wagner, B., & Unruh, T. (2008). Methyl group dynamics in glassy, polycrystalline, and liquid coenzyme Q(10) studied by quasielastic neutron scattering. Journal of Chemical Physics, 129(7). https://dx.doi.org/10.1063/1.2967188

MLA:
Smuda, Christoph, et al. "Methyl group dynamics in glassy, polycrystalline, and liquid coenzyme Q(10) studied by quasielastic neutron scattering." Journal of Chemical Physics 129.7 (2008).

BibTeX: 

Last updated on 2018-06-08 at 14:09