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Characterization of the molecular reorientational dynamics of the neat ionic liquid 1‐butyl‐3‐methylimidazolium bromide in the super cooled state using 1 H and 13 C NMR spectroscopy
Author(s) -
Imanari Mamoru,
Tsuchiya Hiroyuki,
Seki Hiroko,
Nishikawa Keiko,
Tashiro Mitsuru
Publication year - 2009
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2351
Subject(s) - chemistry , ionic liquid , bromide , imidazole , relaxation (psychology) , ring (chemistry) , nmr spectra database , molecular dynamics , methyl group , phase (matter) , crystallography , liquid state , medicinal chemistry , spectral line , analytical chemistry (journal) , stereochemistry , computational chemistry , alkyl , organic chemistry , catalysis , psychology , social psychology , physics , astronomy
Abstract The 13 C spectra and 13 C longitudinal relaxation times ( T 1 ) were measured to investigate the segmental motion of the neat ionic liquid 1‐butyl‐3‐methylimidazolium bromide ([bmim]Br) in the super cooled state. The 13 C signals of the imidazole ring significantly broadened at 283 K, whereas many other signals were unchanged. In the process of lowering temperature, the [bmim]Br changed to the solid state at ca 273 K without showing the rapid phase transition. Only the 13 C signal of the terminal methyl group in the butyl chain was still observed at 263 K, indicating that the motion of the imidazole ring was extremely restricted, whereas the methyl group in the butyl chain was active even in the solid state. The 13 C‐ T 1 values measured as a function of temperature also supported the discrete segmental motions of the [bmim] + cation. Copyright © 2008 John Wiley & Sons, Ltd.