Transient Intermediates of Chemical Reactions

华盛顿大学化学系的Frantisek Turecek教授因其对气相化学反应的瞬态中间体的研究而获得有机和大分子化学计划的支持。拟议研究的目标是（1）在气相中产生与肽，核酸和有机金属化合物的高能化学相关的难以捉摸和高度反应性的自由基，（2）研究瞬态物质的稳定性，解离动力学和光激发，以及（3）使用高级量子化学计算结合RRKM理论获得相对，解离，和活化能的瞬态中间体和计量的解离动力学。基本的实验方法是中和-再电离质谱法（NRMS），使用“非化学”方法产生瞬态物质。在NRMS中，离子和靶之间的短相互作用时间导致在所产生的新生中性物种中保持键连接性和几何形状。提出了新的方法来扩展NRMS方法，研究极性化合物的瞬态中间体，并允许快速离解的测量。这些研究的潜在影响是提供了新的见解，复杂的化学反应的高活性多原子物种，形成短暂的高能量过程。这些研究，辅以计算分析，解决了这些瞬态中间体的稳定性和反应性，阐明了高能过程中发生的基本事件。大气中的氧与含硫分子的反应在全球每年发生100万吨，具有相当大的环境重要性。在有机和高分子化学项目的支持下，Frantisek Turecek教授将在实验室中生成和研究这些反应和相关反应的许多产物。除了研究这些对环境和维持地球上生命具有重要意义的小分子外，Turecek教授的研究重点是与核酸碱基相关的大分子系统。来自核酸碱基的自由基被认为是作为短寿命物种出现的，可以引起RNA和DNA的修饰，特别是在暴露于阳光、背景辐射或其他高能过程引起的辐射损伤中。瞬态中间体的表征对化学的实验和理论方法提出了巨大的挑战。对瞬时中间体的过程和动力学的这种探究在肽测序中具有实际用途的潜力。

Professor Frantisek Turecek, of the Department of Chemistry at the University of Washington, is supported by the Organic and Macromolecular Chemistry Program for his research on transient intermediates of chemical reactions in the gas phase. The objectives of the proposed research are to (1) generate in the gas phase elusive and highly reactive radicals relevant to the high-energy chemistry of peptides, nucleic acids, and organometallic compounds, (2) investigate the stabilities, dissociation kinetics, and photoexcitation of the transient species, and (3) use high-level quantum chemistry calculations combined with RRKM theory to obtain relative, dissociation, and activation energies for the transient intermediates and gauge the dissociation kinetics. The basic experimental method is neutralization-reionization mass spectrometry (NRMS), using a "non-chemical" means to generate transient species. In NRMS the short interaction time between ion and target results in maintaining both bond connectivity and geometry in the nascent neutral species generated. New methods are proposed to extend the NRMS methodologies to study transient intermediates from polar compounds and allow for measurements of fast dissociations. The potential impact of these studies is in providing new insights into the complex chemistries of highly reactive polyatomic species that are formed transiently by high-energy processes. These studies, complemented by computational analyses, address the stabilities and reactivity of these transient intermediates, shedding light on the fundamental events that occur during high-energy processes.The reaction of atmospheric oxygen with molecules containing sulfur occurs on a scale of one million tons per year globally making it of considerable environmental importance. With the support of the Organic and Macromolecular Chemistry Program Professor Frantisek Turecek will generate and study in the laboratory the many products from these and related reactions. In addition to studying these smaller molecules that are of great significance to the environment and sustaining life on this planet, Professor Turecek's research focuses on larger molecular systems relevant to nucleic bases. Radicals derived from nucleic bases are presumed to occur as short lifetime species that can cause the modification of RNA and DNA, especially in radiation damage caused by exposure to sunlight, background radiation, or other high-energy processes. Characterization of transient intermediates represents a formidable challenge to the experimental and theoretical methods of chemistry. This inquiry into the processes and dynamics of transient intermediates has the potential for practical usefulness in peptide sequencing.