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

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Details zur Publikation

Autorinnen und Autoren: Smuda C, Busch S, Wagner B, Unruh T
Zeitschrift: Journal of Chemical Physics
Verlag: AMER INST PHYSICS
Jahr der Veröffentlichung: 2008
Band: 129
Heftnummer: 7
ISSN: 0021-9606
eISSN: 1089-7690


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-Autorinnen und Autoren / FAU-Herausgeberinnen und Herausgeber

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


Einrichtungen weiterer Autorinnen und Autoren

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


Zitierweisen

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).

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