Amadeu, N. D. ; Grünberg, B. ; Frydel, J. ; Werner, M. ; Limbach, H. H. ; Breitzke, H. ; Buntkowsky, G. (2012)
Melting of Low Molecular Weight Compounds in Confinement Observed by H-2-Solid State NMR: Biphenyl, a Case Study.
In: Zeitschrift Fur Physikalische Chemie-International Journal of Research in Physical Chemistry & Chemical Physics, 226 (11-12)
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
The H-2-NMR solid echo spectra of biphenyl molecules as guests in the mesopores of neat and silylated SBA-15 have been measured as a function of temperature. At low temperatures typical H-2-Pake patterns with parameters of (Q(zz) = 132 kHz, corresponding to Q(cc) = 176 kHz) and (eta = 0.04) are observed. All samples exhibit a strong reduction of the melting point from the bulk value of 342.4 K to values between 222 K and 229 K, depending on both the pore diameter and the surface state and a glass like behavior of the biphenyl molecules in the melting regime. Employing the Roessler two-phase model of the modeling of glass-transitions by H-2-solid state NMR the distribution of activation energies for the rotational motions has been determined. At temperatures closely below the glass-transition temperature deviations from a static Pake pattern of an aromatic deuteron are observed, which indicate a pre-melting motion of biphenyl, which could be caused by C-2-ring flips of the phenyl rings.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2012 |
| Autor(en): | Amadeu, N. D. ; Grünberg, B. ; Frydel, J. ; Werner, M. ; Limbach, H. H. ; Breitzke, H. ; Buntkowsky, G. |
| Art des Eintrags: | Bibliographie |
| Titel: | Melting of Low Molecular Weight Compounds in Confinement Observed by H-2-Solid State NMR: Biphenyl, a Case Study |
| Sprache: | Englisch |
| Publikationsjahr: | 2012 |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Zeitschrift Fur Physikalische Chemie-International Journal of Research in Physical Chemistry & Chemical Physics |
| Jahrgang/Volume einer Zeitschrift: | 226 |
| (Heft-)Nummer: | 11-12 |
| Kurzbeschreibung (Abstract): | The H-2-NMR solid echo spectra of biphenyl molecules as guests in the mesopores of neat and silylated SBA-15 have been measured as a function of temperature. At low temperatures typical H-2-Pake patterns with parameters of (Q(zz) = 132 kHz, corresponding to Q(cc) = 176 kHz) and (eta = 0.04) are observed. All samples exhibit a strong reduction of the melting point from the bulk value of 342.4 K to values between 222 K and 229 K, depending on both the pore diameter and the surface state and a glass like behavior of the biphenyl molecules in the melting regime. Employing the Roessler two-phase model of the modeling of glass-transitions by H-2-solid state NMR the distribution of activation energies for the rotational motions has been determined. At temperatures closely below the glass-transition temperature deviations from a static Pake pattern of an aromatic deuteron are observed, which indicate a pre-melting motion of biphenyl, which could be caused by C-2-ring flips of the phenyl rings. |
| Freie Schlagworte: | solid state nmr confinement melting premelting biphenyl mesoporous silica materials nuclear-magnetic-resonance potential applications phase-transitions internal-rotation phenylene motion spin-diffusion drug-delivery glass formers exchange nmr |
| Zusätzliche Informationen: | Sp. Iss. SI 067TE Times Cited:1 Cited References Count:88 |
| Fachbereich(e)/-gebiet(e): | 07 Fachbereich Chemie > Eduard Zintl-Institut > Fachgebiet Physikalische Chemie 07 Fachbereich Chemie |
| Hinterlegungsdatum: | 27 Okt 2014 20:34 |
| Letzte Änderung: | 27 Jul 2015 14:59 |
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