Temperature-dependent 11B spin–lattice relaxation time for BF4 and CF3BF3 anions in room-temperature ionic liquids
✍ Scribed by Kikuko Hayamizu; Seiji Tsuzuki; Shiro Seki
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 146 KB
- Volume
- 49
- Category
- Article
- ISSN
- 0749-1581
- DOI
- 10.1002/mrc.2698
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✦ Synopsis
Abstract
Temperature‐dependent ^11^B T~1~ values were measured for the BF~4~ anion and BF~3~ in the CF~3~BF~3~ anion in room‐temperature ionic liquids (RTILs) composed of the cation N‐diethyl‐N‐methyl‐N‐(2‐methoxyethyl)ammonium (DEME). Including the lithium‐salt‐doped samples, two neat and two binary ionic liquids were studied. Arrhenius plots of the ^11^B T~1~ showed T~1~ minima for BF~4~ in the temperature range between 243 (or above freezing) and 373 K. Using the Bloembergen, Pound, and Purcell(BPP) equations for the ^11^B quadrupolar and ^11^B^19^F dipolar relaxation mechanisms, the correlation times for motions of BF~4~ were calculated. Since the internal rotation of BF~3~ is assumed in CF~3~BF~3~, T~1~ minimum was not observed. The effects of the addition of the lithium salt on the ^11^B correlation time and ^11^B__T__~1~ for the anions in the ILs are discussed. Copyright © 2010 John Wiley & Sons, Ltd.