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

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。我们正在研究合适的前体的热解接种到超声束作为一种手段，以遵循离子与自由基和其他活性物种的反应。我们的测试反应是储存在FTMS电池中的苯自由基阳离子和由1，5-己二烯热解产生的烯丙基自由基的反应。所有的反应都在一个专门设计的FT质谱仪中进行，以下的在线热解的1，5-己二烯在T = 1273 K的喷嘴。研究使用氘代苯和半经验分子轨道计算在PM 3水平提供洞察机制。当热解不完全时，观察到起始1，5-己二烯和产物烯丙基自由基。加合离子的产生表明烯丙基自由基的存在。研究中，电子束被用于电离的反应束表明，电荷交换和形成的离子的m/z 91发生在时间的种子自由基束进入FT-ICR细胞。然而，[加合物- H]不跟踪自由基束的开始;相反，它被延迟3 ms。反应性物质必须在反应之前行进比从喷嘴到电池的距离长得多的距离。现在，仪器的建立和系统的工作，我们打算更好地表征实验系统，并扩大到缺电子含硅系统的反应和生物系统中的自由基损伤可能会导致严重的生物功能的修改。我们还使用离子阱技术直接跟踪其他活性物质的反应（例如，CBr+、SiH+、PBr+）与小有机分子的混合物。此外，我们正在通过使用密度泛函理论（通过在小型戴尔群集上运行的Gaussian 98套件实现）的理论计算来增强这些实验研究。

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.