REACTIVE SPECIES BY FTMS: FREE RADICALS AND ELECTRON-DEFICIENT MAIN GROUP ATOMS

FTMS 测定的反应物质：自由基和缺电子主族原子

• 批准号: 7355152
• 负责人: MICHAEL L GROSS
• 金额: $ 2.13万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-01 至 2007-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7355152
• 关键词: REACTIVE; SPECIES; FTMS; FREE; RADICALS

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. We are investigating pyrolysis of suitable precursors seeded into a supersonic beam as a means to follow reactions of ions with radicals and other reactive species. Our test reaction is that of the benzene radical cation, stored in an FTMS cell, and the allyl radical generated by pyrolysis of 1,5-hexadiene. All reactions were performed in a specially designed FT mass spectrometer, following on-line pyrolysis of 1,5-hexadiene at T = 1273 K in the nozzle. Studies using deuterated benzene and semiempirical MO calculations at the PM3 level give insight to mechanism. When the pyrolysis is incomplete, both the starting 1,5-hexadiene and the product allyl radical are observed. The production of adduct ions indicate the presence of allyl radical. Studies in which an electron beam is used for ionization of the reactive beam showed that both charge exchange and formation of ions of m/z 91 occur at the time the seeded radical beam enters the FT-ICR cell. The [adduct - H], however, does not track the onset of the radical beam; instead, it is delayed by 3 ms. The reactive species must travel a considerably longer distance than that from the nozzle to the cell before reacting. Now that the instrumentation is built and the system working, we intend to characterize better the experimental system and expand to reactions of electron-deficient silicon-containing systems and to biological systems where free radical damage can cause serious modification in biological function. We are also using ion trap technology to follow directly the reactions of other reactive species (e.g., CBr+, SiH+, PBr+) with small organic molecules. In addition, we are augmenting these experimental studies with theoretical calculations by using density functional theory which is implemented through the Gaussian 98 suite running on a small Dell cluster.

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。我们正在研究将合适的前体放入超音速波束中进行热解，作为跟踪离子与自由基和其他活性物种反应的一种手段。我们的测试反应是储存在FTMS池中的苯自由基阳离子和1，5-己二烯裂解产生的烯丙基自由基的反应。所有反应都在专门设计的FT质谱仪中进行，随后在喷嘴中1，5-己二烯在T=1273K下在线裂解。在PM3水平上使用重氢苯和半经验分子轨道计算的研究给出了机理的见解。当热解不完全时，同时观察到起始的1，5-己二烯和产物烯丙基自由基。加合物离子的产生表明烯丙基自由基的存在。电子束用于电离反应束的研究表明，当种子自由基束进入FT-ICR池时，m/z 91离子的电荷交换和形成都发生了。然而，[加法-H]并不跟踪自由基束的开始；相反，它被延迟了3毫秒。在反应之前，活性物质必须比从喷嘴到细胞的距离要长得多。现在仪器已经建立，系统工作正常，我们打算更好地描述实验系统，并将其扩展到缺电子硅系统的反应，以及自由基损伤会导致生物功能严重改变的生物系统。我们还使用离子陷阱技术来直接跟踪其他活性物种(例如，CBr+、SiH+、Pbr+)与有机小分子的反应。此外，我们还使用密度泛函理论对这些实验研究进行了补充，密度泛函理论是通过运行在小型戴尔群集上的Gauss98套件实施的。