Acid-Base Properties of Photoexcited Molecules

我们将研究在羟基芳烃的激发态中发生的酸性增强现象。通过策略设计和定向合成，具有特殊设计的内部质子受体或具有极大增强的光酸活性的新分子已经被制备出来，并将被研究。这些衬底将允许检验激发态质子转移的各种理论，为质子转移引发的反应提供新的研究方法，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。来自有机动力学项目的这笔赠款支持佐治亚理工大学拉伦·M·托尔伯特教授的继续工作。有机分子的重要性质之一是它们的酸性，也就是说，质子转移到底物的难易程度。质子转移在许多反应中起着重要的催化作用，这也是为什么人们对有机分子的酸性产生极大兴趣的原因之一。在紫外光照射下激发的分子，与没有照射时的酸性相比，可能会表现出更强的酸性。这种效应的起源尚不清楚，之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由紫外光激发的分子的质子转移的各种理论。

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.