Paul Aniruddha, Samanta Anunay
School of Chemistry, University of Hyderabad, Hyderabad 500 046, India.
J Phys Chem B. 2007 May 10;111(18):4724-31. doi: 10.1021/jp065790z.
Steady-state and time-resolved fluorescence behaviors of two dipolar solutes, coumarin 153 and 4-aminophthalimide, have been studied in an alcohol-functionalized room-temperature ionic liquid, 1-(hydroxyethyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. The steady-state fluorescence parameters have been exploited for the estimation of the polarity of this ionic liquid and to obtain information on the hydrogen bonding interaction between the ionic liquid and the probe molecules. The time-resolved measurements have been focused on the dynamics of solvation by studying the dynamic Stokes shift in the ps-ns time scale and solute rotation by measuring the time dependence of the fluorescence anisotropy. The time-resolved anisotropy studies reveal a significant slow down of the rotational motion of one of the probe molecules. The time-dependent fluorescence Stokes shift measurements suggest that the time-resolvable part of the dynamics is biphasic in nature, highly dependent on the probe molecule and the ultrafast component is comparatively less than that in other ionic liquids. The influence of the hydrogen bonding interaction between the probe molecules and the ionic liquids on the solute rotation and the various components of the solvation dynamics is carefully analyzed in an attempt to obtain further insight into the mechanism of solvation in these novel media.
在一种醇官能化的室温离子液体1-(羟乙基)-3-甲基咪唑双(三氟甲磺酰)亚胺中，研究了两种偶极溶质香豆素153和4-氨基邻苯二甲酰亚胺的稳态和时间分辨荧光行为。利用稳态荧光参数来估计这种离子液体的极性，并获取有关离子液体与探针分子之间氢键相互作用的信息。时间分辨测量通过研究皮秒-纳秒时间尺度上的动态斯托克斯位移以及通过测量荧光各向异性的时间依赖性来关注溶剂化动力学和溶质旋转。时间分辨各向异性研究表明，其中一种探针分子的旋转运动显著减慢。随时间变化的荧光斯托克斯位移测量表明，动力学中可时间分辨的部分本质上是双相的，高度依赖于探针分子，并且超快成分比其他离子液体中的相对要少。仔细分析了探针分子与离子液体之间的氢键相互作用对溶质旋转和溶剂化动力学各组分的影响，以期进一步深入了解这些新型介质中的溶剂化机制。
