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Melting of Low Molecular Weight Compounds in Confinement Observed by ²H-Solid State NMR: Biphenyl, a Case Study

Sousa Amadeu, Nader de ; Grünberg, Bob ; Frydel, Jarek ; Werner, Mayke ; Limbach, Hans-Heinrich ; Breitzke, Hergen ; Buntkowsky, Gerd (2021):
Melting of Low Molecular Weight Compounds in Confinement Observed by ²H-Solid State NMR: Biphenyl, a Case Study. (Publisher's Version)
In: Zeitschrift für Physikalische Chemie, 226 (11-12), pp. 1169-1186. De Gruyter, ISSN 0942-9352, e-ISSN 2196-7156,
DOI: 10.26083/tuprints-00019687,
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Item Type: Article
Origin: Secondary publication service
Status: Publisher's Version
Title: Melting of Low Molecular Weight Compounds in Confinement Observed by ²H-Solid State NMR: Biphenyl, a Case Study
Language: English
Abstract:

The ²H-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 ²H-Pake patterns with parameters of (Qzz = 132 kHz, corresponding to Qcc = 176 kHz) and (η = 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 ²H-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 C₂-ring flips of the phenyl rings.

Journal or Publication Title: Zeitschrift für Physikalische Chemie
Journal volume: 226
Number: 11-12
Publisher: De Gruyter
Classification DDC: 500 Naturwissenschaften und Mathematik > 540 Chemie
Divisions: 07 Department of Chemistry > Physical Chemistry
Date Deposited: 01 Oct 2021 11:29
Last Modified: 01 Oct 2021 11:30
DOI: 10.26083/tuprints-00019687
Corresponding Links:
URN: urn:nbn:de:tuda-tuprints-196879
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/19687
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