Measurements of the complete solvation response of coumarin 153 in ionic liquids and the accuracy of simple dielectric continuum predictions.
Measurements of the complete solvation response of coumarin 153 in ionic liquids and the accuracy of simple dielectric continuum predictions.
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DOI：
10.1039/c1fd00058f
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发表时间：
2012
影响因子：
3.4
通讯作者：
M. Maroncelli;Xin-Xing Zhang;Min Liang;Durba Roy;N. Ernsting
中科院分区：
文献类型：
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作者：
M. Maroncelli;Xin-Xing Zhang;Min Liang;Durba Roy;N. Ernsting
利用飞秒宽带荧光上转换和皮秒时间相关单光子计数技术，测定了香豆素153（C153）在不同离子液体中10（-13）-10（-8）s范围内的完全溶剂化响应.这些数据一起使用最近报道的介电数据在8个离子液体测试一个简单的连续模型预测溶剂化动力学的准确性。在大多数情况下，由介电连续模型预测的溶剂化响应函数的功能是类似的C153的测量动力学。然而，预测的动态系统地比观察到的要快，平均为3-5倍。模型溶质/离子液体系统的计算机模拟也表现出相同的介电预测和观察到的动态之间的关系。模拟点的极化响应的空间分散作为一个重要的贡献者在离子液体中的溶剂化速率的过度预测。
The complete solvation response of coumarin 153 (C153) has been determined over the range 10(-13)-10(-8) s in a variety of ionic liquids by combining femtosecond broad-band fluorescence upconversion and picosecond time-correlated single photon counting measurements. These data are used together with recently reported dielectric data in eight ionic liquids to test the accuracy of a simple continuum model for predicting solvation dynamics. In most cases the features of the solvation response functions predicted by the dielectric continuum model are similar to the measured dynamics of C153. The predicted dynamics are, however, systematically faster than those observed, on average by a factor of 3-5. Computer simulations of a model solute/ionic liquid system also exhibit the same relationship between dielectric predictions and observed dynamics. The simulations point to spatial dispersion of the polarization response as an important contributor to the over-prediction of solvation rates in ionic liquids.