Communication: Synperiplanar to antiperiplanar conformation changes as underlying the mechanism of Debye process in supercooled ibuprofen
PBN-AR
Instytucja
Wydział Chemii (Uniwersytet im. Adama Mickiewicza w Poznaniu)
Informacje podstawowe
Główny język publikacji
en
Czasopismo
JOURNAL OF CHEMICAL PHYSICS
ISSN
0021-9606
EISSN
1089-7690
Wydawca
AMER INST PHYSICS
DOI
URL
Rok publikacji
2013
Numer zeszytu
11
Strony od-do
111103
Numer tomu
139
Link do pełnego tekstu
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Autorzy
(liczba autorów: 11)
Pozostali autorzy
+ 10
Słowa kluczowe
MOLECULAR-DYNAMICS;
AMORPHOUS IBUPROFEN;
SPECTROSCOPY;
RELAXATION;
ALCOHOLS;
LIQUIDS
Streszczenia
Język
Treść
In this Communication, we present experimental studies that put new insight into the puzzling nature of the Debye relaxation found in the supercooled liquid state of racemic ibuprofen. The appearance of D-relaxation in the loss spectra of non-hydrogen bonding methylated derivate of ibuprofen has proven that Debye relaxation is related solely with conformational changes of the carboxyl group, termed in this paper as synperiplanar-antiperiplanar. Our studies indicate that the presence of hydrogen bonding capabilities is not here the necessary condition to observe Debye process, however, their occurrence might strongly influence a-and D-relaxations dynamics. Interestingly, the activation energy of the D-process in ibuprofen methyl ester on approaching T-g was found to be perfectly consistent with that reported for ibuprofen by Affouard and Correia [J. Phys. Chem. B 114, 11397-11402 (2010)] (similar to 39 kJ/mol). Finally, IR measurements suggest that the equilibrium between conformers concentration depends on time and temperature, which might explain why the appearance of D-relaxation in supercooled ibuprofen depends on thermal history of the sample. (C) 2013 AIP Publishing LLC.
Inne
System-identifier
PX-58ae9d3ad5dee56058288bcc
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