Probing Nanostructural Organization in Room Temperature Ionic Liquids Using Optical Kerr Effect Spectroscopy

德克萨斯理工大学的Edward Quitevis得到了实验物理化学计划的支持，该计划旨在研究纳米结构组织在室温离子液体(RTIL)分子间动力学中的作用。主要的方法将是使用光学克尔效应(OKE)光谱来探测RTIL动力学。研究的第一部分讨论了RTIL在体相中的行为，并解决了以下问题：(1)当没有纳米结构组织时，RTIL中的分子间动力学有何不同？(2)如果电荷有序在决定二元混合物的分子间动力学中起关键作用，如果RTIL组分具有相同大小的公共阳离子但不同的阴离子，混合物的OKE谱是否是非相加的？(3)温度无关的OKE谱是否存在温度无关的OKE谱变得依赖于温度？(4)如果RTIL组分具有共同的阴离子但具有不同烷基链长的阳离子，二元混合物的OKE谱是否仍然是纳米结构的？研究的第二部分涉及纳米多孔二氧化硅溶胶-凝胶玻璃中RTIL的行为。这里要解决的问题是，在体相中以纳米结构组织的RTIL是否仍然在硅溶胶-凝胶玻璃孔中保持这种组织，以及是否可以通过改变孔径大小或改变孔表面的化学性质来控制纳米结构组织(如果存在)。这一结果有望有助于理解RTILs的结构-功能关系，从而影响人们对具有高导电性和良好机械稳定性的电解液以及纳米液体催化剂日益感兴趣的重要技术领域。RTILs的性质使其有可能取代目前用作溶剂的许多挥发性有机液体。工业使用离子液体溶剂可以消除目前普遍使用的挥发性溶剂带来的健康和环境风险。在研究中对RTIL结构-功能关系的理解将对那些寻求了解离子液体并针对特定应用定制它们的人具有实际意义。除了技术上的好处，这个项目还包括一个强大的教育部分，将为本科生、研究生和博士后研究人员提供研究培训。PI已经制定了一个试点计划，招募代表人数不足的少数族裔学生，他们将参加他所在的小组在德克萨斯理工大学的夏季本科生研究活动。

Edward Quitevis of Texas Tech University is supported by the Experimental Physical Chemistry Program to study the role of nanostructural organization in the intermolecular dynamics of room temperature ionic liquids (RTILs). The main approach will be to use optical Kerr effect (OKE) spectroscopy to probe RTIL dynamics. The first part of the research deals with the behavior of RTILs in the bulk phase, and addresses the following questions: (1) How do the intermolecular dynamics differ in RTILs when nanostructural organization is absent? (2) If charge ordering plays a key role in determining the intermolecular dynamics of binary mixtures, will the OKE spectra of mixtures be nonadditive if the RTIL components have a common cation but different anions of the same size? (3) Is there a temperature above which temperature-independent OKE spectra become temperature-dependent? (4) Will binary mixtures still be nanostructurally organized if the RTIL components have a common anion but cations with different alkyl chain lengths? The second part of the research deals with the behavior of RTILs in nanoporous silica sol-gel glasses. The issues to be addressed here are whether RTILs that are nanostructurally organized in the bulk phase still maintain that organization in the silica sol-gel glass pores, and whether the nanostructural organization, if it exists, can be controlled by varying pore size or modifying the chemical nature of the pore surface. Outcomes are expected to shed light on the understanding of structure-function relationships in RTILs, and therefore impact technologically important areas where there is growing interest in electrolytes with high conductivity and good mechanical stability, and in the study of nanoliquid catalysis.The properties of RTILs make them potential replacements for many volatile organic liquids currently in use as solvents. Industrial use of ionic liquid solvents could eliminate the health and environmental risks that are posed by volatile solvents currently in common use. The understanding of the structure-function relationships of RTILs in the studies will be of practical used to those who seek to understand ionic liquids and tailor them for specific applications. Beyond the technological benefits, this project includes a strong educational component that will provide research training to undergraduate, graduate, and postdoctoral researchers. The PI has developed a pilot program to recruit underrepresented minority students who will participate in summer undergraduate research activities in his group at Texas Tech.