Two-dimensional ultrafast vibrational spectroscopy of azides in ionic liquids reveals solute-specific solvation
Two-dimensional ultrafast vibrational spectroscopy of azides in ionic liquids reveals solute-specific solvation
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DOI：
10.1039/c5cp02119g
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发表时间：
2015-01-01
影响因子：
3.3
通讯作者：
Garrett-Roe, Sean
中科院分区：
文献类型：
--
作者：
Dutta, Samrat;Ren, Zhe;Garrett-Roe, Sean
叠氮化物在离子液体中的双分子亲核取代反应的立体化学和反应速率受溶质-溶剂相互作用的影响。二维超快振动光谱（2D-IR）表明，在一系列同系咪唑离子液体中，无机叠氮化物的皮秒动力学比有机叠氮化物慢得多.在水中，有机和无机叠氮化物都以类似于2 ps的时间常数光谱扩散。在非质子溶剂四氢呋喃中，两种叠氮化物在>5 ps的时间尺度上光谱扩散。在离子液体中，如1-丁基-3-甲基咪唑四氟硼酸盐（[BMIM][BF 4]），有机叠氮化物以2- 4ps的时间常数光谱扩散，无机叠氮化物以>40 ps的时间常数光谱扩散。这种显著的差异表明，中性（有机）和带电（无机）叠氮化物被纳入不同的溶剂化结构的离子液体。
The stereochemistry and the reaction rates of bimolecular nucleophilic substitution reactions involving azides in ionic liquids are governed by solute-solvent interactions. Two-dimensional ultrafast vibrational spectroscopy (2D-IR) shows that the picosecond dynamics of inorganic azides are substantially slower than organic azides in a series of homologous imidazolium ionic liquids. In water, both organic and inorganic azides spectrally diffuse with a similar to 2 ps time constant. In the aprotic solvent tetrahydrofuran, both kinds of azides spectrally diffuse on a timescale >5 ps. In ionic liquids, like 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), organic azides spectrally diffuse with a 2-4 ps time constant, and inorganic azides spectrally diffuse with a >40 ps time constant. Such a striking difference suggests that neutral (organic) and charged (inorganic) azides are incorporated in the ionic liquids with different solvation structures.