Acid-Base Properties of Photoexcited Molecules

研究了羟基芳烃激发态中酸性增强的现象。通过战略设计和定向合成，具有专门设计的内部质子受体或具有极大增强的光酸性的新分子已经制备出来并将被研究。这些衬底将允许测试各种激发态质子转移理论，提供研究质子转移引发反应的新方法，并产生基态方法无法获得的新结构。这些研究将涉及分子轨道计算，目标分子的有机合成，时间分辨纳秒荧光和其他光谱技术，以及结构分析。这项来自有机动力学项目的资助用于支持乔治亚理工大学的Laren M. Tolbert教授的持续工作。有机分子的一个重要性质是它们的酸度，也就是说，质子转移到底物上的容易程度。质子转移在许多反应的催化中起着重要的作用，这也是人们对有机分子的酸性非常感兴趣的原因之一。与没有照射时的酸性相比，被紫外线照射激发的分子可能显示出增强的酸性。这种效应的起源尚不清楚，以前的解释可能是错误的。在目前的研究中，分子将被专门设计来测试各种质子转移理论，这些理论是由紫外线照射激发的分子。

The phenomenon of enhanced acidity occurring in the excited state of hydroxyarenes will be studied. Through strategic design and directed synthesis, new molecules with specifically designed internal proton acceptors or with greatly enhanced photoacidity have been prepared and will be studied. These substrates will allow the testing of various theories of exited state proton transfer, provide new methods of studies of proton transfer initiated reactions, and yield novel structures unattainable by ground state methods. These studies will involve molecular orbital calculations, organic synthesis of target molecules, time-resolved nanosecond fluorescence and other spectroscopic techniques, and structure analysis. %%% This grant from the Organic Dynamics Program supports the continuing work of Professor Laren M. Tolbert at Georgia Tech University. One of the important properties of organic molecules is their acidity, that is, how readily a proton can be transferred to a substrate. Proton transfers are important in the catalysis of many reactions and this is one of the reasons for the great interest in the acidity of organic molecules. Molecules that are excited by irradiation with ultraviolet light may display enhanced acidity, compared to their acidity in the absence of irradiation. The origin of this effect is not well understood and previous explanations may be in error. In the present study, molecules will be specifically designed to test various theories of proton transfer from molecules that are excited by ultraviolet light irradiation.