Local Structure of Ionic Liquids Probed by Self-quenching of Thiobenzophenone
Local Structure of Ionic Liquids Probed by Self-quenching of Thiobenzophenone
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硫代二苯甲酮自猝灭探测离子液体的局域结构
DOI：
10.1039/c2cp42766d
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
M. Wakasa
中科院分区：
文献类型：
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作者：
M. Tanaka;T. Yago;M. Wakasa
使用纳秒激光闪光光解测量分子溶剂、十二烷基硫酸钠 (SDS) 胶束溶液和离子液体 (IL) 中噻二苯甲酮 (3TBP*) 三重激发态的自猝灭。在分子溶剂和离子液体中，3TBP*单指数衰减，并且随着TBP浓度的增加衰减加速。在离子液体中获得的自猝灭速率常数（kSQ）小于在具有相似溶剂粘度的分子溶剂中获得的自猝灭速率常数（kSQ），表明分子扩散在离子液体中受到抑制。在 SDS 胶束溶液中，3TBP* 的衰变显示出两个分量。快速衰减成分归因于 3TBP* 的自猝灭，其存在于含有两个或多个 TBP 分子的胶束内，而慢速衰减成分则来自单个 3TBP* 的失活。 3TBP* 在 IL、N,N,N-三甲基-N-丙基铵双(三氟甲基磺酰基)酰胺 (TMPA TFSA) 中的衰变仅具有一种衰变成分，这表明与胶束不同，TMPA TFSA 的局部结构的寿命并不长。 TMPA TFSA 的笼寿命估计在 17 至 20 ns 之间。
Self-quenching of the triplet excited state of thiobenzophenone (3TBP*) in molecular solvents, a sodium dodecyl sulfate (SDS) micellar solution, and ionic liquids (ILs) was measured using nanosecond laser flash photolysis. In the molecular solvents and ILs, 3TBP* single-exponentially decayed, and the decay was accelerated with increasing TBP concentration. Self-quenching rate constants (kSQ) obtained in the ILs were smaller than those in the molecular solvents with similar solvent viscosities, indicating that molecular diffusion is inhibited in the ILs. In the SDS micellar solution, the decay of 3TBP* showed two components. The fast decay component was attributed to self-quenching of 3TBP* which presents inside micelles containing two or more TBP molecules, while the slow decay component was from deactivation of single 3TBP*. The decay of 3TBP* in an IL, N,N,N-trimethyl-N-propylammonium bis(trifluoromethylsulfonyl)amide (TMPA TFSA), had only one decay component, showing that unlike the micelles, the local structure of TMPA TFSA does not have a long lifetime. The cage lifetime of TMPA TFSA was estimated to be between 17 and 20 ns.