Mass Spectrometric Studies of Spin Control in Open-Shell Molecules

该项目涉及对开壳层分子和离子反应性的热化学性质进行质谱研究。该提案描述了旨在调查电子在开壳层系统中相互作用的机制的研究。 这项工作的目标是提供洞察如何控制开壳层系统的自旋，通过战略性地选择结构图案，利用适当的机械方面。 控制自旋的三种方法是：1）拓扑方法：该领域的重点是不相交的双自由基，并使用连接性将它们创建为三重态或单重态。 拓扑结构的作用将通过对比结构相关但拓扑结构不同的双烯丙基双自由基的性质（如电子亲合性）来研究。2）杂原子取代：用氮或氧化氮取代已被充分研究的烃双自由基中的碳可以改变基态和激发态能量排序。 这种影响将通过检查吡啶和吡啶-N-氧化物为基础的双自由基的热化学性质进行研究，通过使用能量分辨碰撞诱导解离研究确定。3）取代：芳香族氮烯的电子状态顺序被改变通过使用取代基上的芳香环或旁边的氮烯中心。 取代苯基氮烯自由基阴离子的负离子光电子能谱将用于研究中性苯基氮烯的电子亲合势和激发态的能量。气相反应性和结构的研究可以影响化学的所有领域以及其他学科，如材料科学和工程。 机理研究提供了可用于开发新的反应性方法的见解。 而开壳物种，如双自由基和三自由基的结构研究提供了深入了解键合和反应性，它们也提供了工程和材料科学方法的基础磁性材料。 本提案中描述的工作也是普渡大学多样化和有才华的研究生群体教育的重要组成部分。 这种支持还允许PI利用他在NSF研究生研究奖学金计划中的经验，鼓励本科生在当地ACS学生联盟和Alpha Chi Sigma分会的活动，特别是在为学生开发创造性的方式来服务和影响社区方面。

The project involves mass spectrometry studies of the thermochemical properties of the reactivity of open-shell molecules and ions. The proposal describes studies designed to investigate the mechanisms through which electrons can interact in open-shell systems. The goal of the work is to provide insight into how to control the spin of open-shell system by strategically choosing structural motifs that exploit the appropriate mechanistic aspects. The three methods of controlling spin are:1) Topological approaches : the focus of this area is on disjoint diradicals and using connectivity to create them in either triplet or singlet states. The role of topology will be investigated by contrasting the properties, such as electron affinities, of structurally related but topologically distinct bis-allylic diradicals.2) Heteroatom substitution : replacing a carbon in well-studied hydrocarbon diradicals with nitrogen or oxidized nitrogen can change the ground and excited state energy orderings. This effect will be investigated by examining the thermochemical properties of pyridine- and pyridine-n-oxide based diradicals, determined by using energy-resolved collision-induced dissociation studies.3) Substitution : the electronic state ordering of aromatic nitrenes is altered by using substituents either on the aromatic ring or next to the nitrene center. Negative ion photoelectron spectroscopy of substituted phenylnitrene radical anions will be used to investigate the electron affinities and the energies of the excited states in the neutral phenyl nitrenes.Gas-phase studies of reactivity and structure can impact all areas of chemistry as well as other disciplines such as material science and engineering. Mechanistic studies provide insight that can be used to develop new reactivity methodologies. Whereas structural studies of open-shell species such as diradicals and triradicals provide insight into bonding and reactivity, they also provide a foundation for engineering and material science approaches to magnetic materials. The work described in this proposal is also an important component of the education of a diverse and talented group of graduate students at Purdue University. This support also allows the PI to utilize his experience with the NSF Graduate Research Fellowship Program to encourage and activities of the undergraduate students in the local ACS Student Affiliates and Alpha Chi Sigma chapters, particularly in regards to developing creative ways for the students to serve and impact the community.