Gas-Phase Studies of Organic Sigma-type Polyradicals

有机双自由基和多自由基在溶液中的高活性和短寿命阻碍了它们的反应性研究。例如，人们对控制许多以碳为中心的自由基的化学性质的因素所知甚少，对相关的三自由基和四自由基的化学性质一无所知。然而，控制这些物种化学性质的因素的信息是非常需要的，因为它可以允许人们通过改变结构细节来“调整”它们的反应性，从而设计出具有定制性质的多自由基。这种能力有望影响许多领域，包括有机合成、材料科学（如有机磁体）和药物开发。过去，PI和她的学生使用傅里叶变换离子回旋共振质谱仪（FT-ICR），流动的余光四极-八极-四极装置，以及最近的线性四极离子阱，研究了气态单基和双基的反应性。这些研究揭示了几个重要的反应性控制因素，可以用来“调整”这些物种的反应性。该项目将这些研究扩展到类似的三自由基和四自由基，其反应性几乎完全未被探索。几种异构体和不同取代的三自由基和四自由基的性质将通过对其反应性的实验研究和对其几何形状和电子结构的计算研究来探索。20多名研究生和至少5名本科生将进行研究的各个方面，并在PI的监督下传播结果。大约一半的参与学生是女性和/或属于代表性不足的少数民族。此外，质谱法将被引入普渡大学的科学学院，该学院为印第安纳州中部的高中和初中提供研究级仪器。拟议的研究将导致培养大量不同种族、高素质的科学博士。

Reactivity studies on organic bi- and polyradicals are hindered by their high reactivity and short lifetime in solution. Only little is known, for example, about the factors that control the chemical properties of many carbon-centered radicals, and nothing is known about the chemical properties of related tri- and tetraradicals. However, information on the factors that control the chemical properties of these species is highly desirable since it may allow one to "tune" their reactivity by varying structural details and hence design polyradicals with tailored properties. The ability to do this is expected to impact many fields, including organic synthesis, materials science (e.g., organic magnets), and drug development. In the past, PI and her students have studied the reactivity of gaseous mono- and biradicals by using Fourier-transform ion cyclotron resonance mass spectrometers (FT-ICR), a flowing afterglow quadrupole-octapole-quadrupole apparatus, and most recently, a linear quadrupole ion trap. These studies have revealed several important reactivity controlling factors that can be used to "tune" the reactivity of these species. This project will extend these studies to analogous tri- and tetraradicals whose reactivity is nearly entirely unexplored. The properties of several isomeric and differently substituted tri- and tetraradicals will be explored by experimental studies on their reactivity and by computational studies on their geometries and electronic structures. More than 20 graduate and at least five undergraduate students will carry out all aspects of the research, and disseminate the results under the PI's supervision. About half of the participating students are female and/or belong to underrepresented minorities. Further, mass spectrometry will be introduced to Purdue's College of Science Van that delivers research grade instruments to high and middle schools throughout central Indiana. The proposed research will lead to the training of a large number of ethnically diverse, highly qualified science Ph.D.'s.