Chemical and Spectroscopic Investigation of Nitrenium Ions

本研究将涉及芳基氮离子生成的光谱和动力学评价。虽然该项目的初始阶段将涉及到蒽盐的光解，但预计最终将出现几种用于一般生产芳基氮离子的新的光化学方法。该研究将集中于利用纳秒激光闪光光解、低温ESR光谱和分子轨道计算来提供明确的芳基氮离子鉴定。这项工作的一个亮点将是定义所产生的氮离子的自旋多重性和从每个自旋态形成的产物。将回答单重态-三重态平衡存在的问题，并描述其对最终产品分布的影响。芳基氮离子在DNA损伤反应中的作用也将通过鸟嘌呤捕获芳基氮离子来模拟致癌反应来研究。这项来自有机动力学计划的新拨款支持了马里兰大学丹尼尔·a·法尔维教授的工作。这项调查将试图分析一种叫做氮离子的寿命很短的分子的反应性。氮离子具有一个带正电荷的氮，很少受到关注，但它代表了一类潜在的活性物质，在光诱导的化学过程中具有广泛的用途。通过使用一种设计用于拍摄瞬时化学物质的紫外吸收快照的仪器，这些化学物质的寿命为几十亿分之一秒，这将有可能确认芳胺氮离子的存在，芳胺氮离子被认为是芳胺DNA损伤过程中涉及的主要实体。

This investigation will deal with spectroscopic and kinetic evaluation of the generation of arylnitrenium ions. Although the initial phase of the project will involve the photolysis of anthranilium salts, it is expected that several new photochemical methods for the general production of arylnitrenium ions will eventually emerge. The study will center on the use of nanosecond laser flash photolysis, low temperature ESR spectroscopy, and molecular orbital calculations to provide unequivocal identification of arylnitrenium ions. A highlight of the work will be to define the spin-multiplicity of the nitrenium ions generated and the products formed from each spin state. The question of the existence of a singlet-triplet equilibrium will be answered and the consequences for final product distribution will be delineated. The role of arylnitrenium ions in DNA damaging reactions will also be investigated by trapping of arylnitrenium ions with guanine to simulate carcinogenetic reactivity. %%% This new grant from the Organic Dynamics Program supports the work of Professor Daniel A. Falvey at the University of Maryland. The investigation will seek to analyze the reactivity of very short lived molecules called nitrenium ions. Nitrenium ions, which possess a nitrogen with a positive charge, have received little attention and yet represent a potential class of reactive species with widespread utility in chemical processes induced by light. By using an instrument designed to take snap-shot ultraviolet absorption "pictures" of transient chemical species which live a few billionths of a second, it will be possible to confirm the existence of arylnitrenium ions which have been implicated as the primary entities involved in the DNA damaging process of arylamines.