FRAGMENTATION OF SMALL GAS PHASE IONS: THEORY & EXPERIMENT

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者的研究机构。 具有生物学意义的小离子的碎裂机制正在通过从头算和密度泛函方法进行探索。 计算的执行，以获得热化学信息，结构，和过渡态的碎裂过程，沿着各种小分子离子的离子-分子反应及其随后的模式的碎裂。为了完成这项工作，我们建立了一个小型的戴尔计算机集群，并在本周期中进行了扩展，专门用于这些计算。 当需要时，我们将理论工作与使用MS/MS（离子阱，三扇区，四扇区），动能释放，同位素标记，反应性相关性以及其他在机制研究中重要的工具的实验相结合。 这是研究资源在质谱领域的一个独特的研究领域，我们的目标是提供一个解决适用于生物分子的有趣的质谱碎片问题的资源。 目前，我们正在完成有趣的环化反应的工作，这些反应发生在溶液中，可以通过使用ESI，MS/MS和密度泛函理论在气相中建模。 我们正在应用类似的方法，可能的环加成反应，涉及五元环杂环（呋喃，噻吩，吡咯）。 其动机是探索这些反应是否可以通过使其中一种试剂成为自由基阳离子来加速，从而为药物和相关材料的化学合成提供机会。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The mechanisms for fragmentation of small ions that have biological significance are being explored by ab initio and density functional methods. The calculations are executed to obtain thermochemical information, structures, and transition states for fragmentation processes, along with ion-molecule reactions of various small molecule ions and their subsequent patterns of fragmentation. To carry out this work, we have set up a small cluster of Dell computers, which we have expanded in this cycle, that are devoted to these calculations. When needed, we couple the theoretical work with experiments using MS/MS (ion trap, three sector, four sector), kinetic-energy release, isotope labeling, reactivity correlation, and other tools that are important in mechanism studies. This is a unique area of research for Research Resources in the mass spectrometry area, and our goal is to provide a resource for solving interesting mass spectral fragmentation problems that apply to biological molecules. Currently, we are finishing work on interesting cyclization reactions that take place in solution and can be modeled in the gas phase by using ESI, MS/MS, and density functional theory. We are applying a similar approach to possible cycloaddition reactions involving five-membered ring heterocycles (furan, thiophene, pyrrole). The motivation is to explore whether these reactions, which occur very slowly for neutral molecules, can be accelerated by making one of the reagents a radical cation, thus offering opportunities in the chemical synthesis of drugs and related materials.