A New Molecular Approach toward Liquid-phase Chemical Reactions

本合作研究的目的是了解溶质分子与溶剂分子之间的相互作用在分子基础上的溶剂效应。为此目的，采取了下列办法。(1)小的范德华团簇可以作为溶质分子被少量溶剂分子溶解的模型。在这种情况下，可以使用光谱测量来确定簇的结构，因此可以讨论分子相互作用的细节。在大簇的情况下，结构可以从热力学数据和破碎模式估计。利用这种给定结构的簇，研究了分子内化学反应和能量转移。(2)以超临界流体为溶剂，发现溶解在超临界流体中的极性分子被溶剂流体分子包围，在室温下作为独立溶剂化分子存在。研究了这种特殊溶剂化分子的异构化和电荷转移反应。(3)液体溶液在真空中破碎，发现液体溶液的射流膨胀形成了分子大小的碎片，这些碎片反映了溶液的真实结构，特别是在氢键溶剂中。(4)溶剂分子运动的飞秒观察：溶剂分子在光电离和光诱导电荷转移反应后的超快速运动。(5)基质中的反应在77K的玻璃基质中研究了自由基阳离子的反应，推断了分子相互作用对化学反应的影响信息。今年召开了两次会议，讨论了上述五个研究领域的主题和发展，热烈的讨论有助于个别与会者在实验和理论上发展自己的研究项目。

The aim of this cooperative research is to understand the solvent effect on molecular basis as the interaction between a solute and solvent molecules. For this purpose the following approaches were adopted.(1) Cluters as a model of solvated molecules Small van der Waals clusters can be served as a model of solute molecules solvated by a small number of solvent molecules. In this case, the structure of the cluster can be determined using spectroscopic measurement and hence the details of the molecular interaction can be discussed. In the case of large clusters, the structure can be estimated from the thermodynamic data and fragmentation pattern. Using such clusters of a given structure, intramolecular chemical reaction and energy transfer have been studied.(2) Using Supetcritical fluid as solvent A polar molecules dissolved in supercritical fluid was found to be surrounded by solvent fluid molecules and served as an independently solvated molecule at room temperature. Isomerization and charge-transfer reactions were studied for this particular solvated molecules.(3) fragmentation of liquid solution into vacuum Jet expansion of liquid solution was found to forms the molecular size fragments and these fragments were proved to reflect the real structure of solution phase especially in the case of hydrogen-bonded solvent.(4) femt-second observation of the motion of solvent molecules The ultra-fast motion of solvent molecules were followed after photo-ionization and photo-induced charge-transfer reactions.(5) Reactions in matrix Reactions of radical cations were studied in glassy matrix at 77K and the information of the effect of molecular interaction on chemical reactions can be inferred.Two meetings were held this year on the topics and the development of the above five research fields and hot discussions there helped individual attendant to develop his research project both experimentally and theoretically.