Methyl dynamics flattens barrier to proton transfer in crystalline tetraacetylethane

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dc.contributor.authorKearley, GJen_AU
dc.contributor.authorStare, Jen_AU
dc.contributor.authorKutteh, Ren_AU
dc.contributor.authorDaemen, LLen_AU
dc.contributor.authorHartl, MAen_AU
dc.contributor.authorEckert, Jen_AU
dc.date.accessioned2012-06-20T02:43:12Zen_AU
dc.date.available2012-06-20T02:43:12Zen_AU
dc.date.issued2012-03-08en_AU
dc.date.statistics2012-06-20en_AU
dc.description.abstractWe analyze the interplay between proton transfer in the hydrogen-bond bridge, O center dot center dot center dot H center dot center dot center dot O, and lattice dynamics in the model system tetraacetylethane (TAB) (CH(3)CO)(2)CH=CH(COCH(3))(2) using density functional theory. Lattice dynamics calculations and molecular dynamics simulations are validated against neutron scattering data. Hindrance to the cooperative reorientation of neighboring methyl groups at low temperatures gives a preferred O atom for the bridging proton. The amplitude of methyl torsions becomes larger with increasing temperature, so that the free-energy minimum for the proton becomes flat over 0.2 angstrom. For the isolated molecule, however, we show an almost temperature-independent symmetric double-well potential persists. This difference arises from the much higher barriers to methyl torsion in the crystal that make the region of torsional phase space that is most crucial for symmetrization poorly accessible. Consequently, the proton-transfer potential remains asymmetric though flat at the base, even at room temperature in the solid. © 2012, American Chemical Society.en_AU
dc.identifier.citationKearley, G. J., Stare, J., Kutteh, R., Daeman, L. L., Hartl, M. A., & Eckert, J. (2012). Methyl dynamics flattens barrier to proton transfer in crystalline tetraacetylethane. Journal of Physical Chemistry A, 116(9), 2283-2291. doi:10.1021/jp210212qen_AU
dc.identifier.govdoc4322en_AU
dc.identifier.issn1089-5639en_AU
dc.identifier.issue9en_AU
dc.identifier.journaltitleJournal of Physical Chemistry Aen_AU
dc.identifier.pagination2283-2291en_AU
dc.identifier.urihttp://dx.doi.org/10.1021/jp210212qen_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/4345en_AU
dc.identifier.volume116en_AU
dc.language.isoenen_AU
dc.publisherAmerican Chemical Societyen_AU
dc.subjectProtonsen_AU
dc.subjectNeutron diffractionen_AU
dc.subjectCrystallizationen_AU
dc.subjectApproximationsen_AU
dc.subjectDensityen_AU
dc.subjectCrystal latticesen_AU
dc.titleMethyl dynamics flattens barrier to proton transfer in crystalline tetraacetylethaneen_AU
dc.typeJournal Articleen_AU
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