Gas-Phase Studies of Substituted Aromatic Radicals, Biradicals and Polyradicals

在有机动力学项目和数学与物理科学理事会多学科活动办公室的支持下，普度大学化学系的Hilkka I. Kenttamaa教授开展了取代芳香族自由基、双自由基和多自由基的气相研究。通过生成包含带正电基团的芳香自由基，Kenttamaa教授能够使用傅里叶变换离子回旋共振质谱法在清洁条件下检查其固有或无溶剂反应性，允许评估反应速率常数，产物分支比和热化学参数，如键解离能。研究了苯基、苄基和其他芳香单自由基和多自由基除携带远端带电基团外还携带中性取代基的取代基的取代效应，并利用自由基陷阱探讨了极性效应在不同类型的自由基反应中的重要性。对于双基，反应性和预测基态多重性之间的关系进行了研究，该信息用于搜索自旋选择性气相反应。普渡大学化学系的Hilkka I. Kenttamaa教授在有机动力学项目和数学与物理科学理事会多学科活动办公室的支持下，研究含有一个或多个不成对电子（“自由基”）的分子化学。通过对自由基的适当选择，Kenttamaa教授能够采用气相技术来研究自由基的形成和反应性，在没有溶剂或其他潜在反应物质的复杂影响的情况下，可以评估自由基的内在性质。通过这些研究，我们获得了关于缺电子分子化学的基本知识，促进了对取代基效应和极性效应在控制其反应性中的作用的理解，并在基于自由基的有机合成和有机材料研究领域提供了潜在的进展。

With the support of the Organic Dynamics Program and the Office of Multidisciplinary Activities of the Mathematical and Physical Sciences Directorate, Professor Hilkka I. Kenttamaa, of the Department of Chemistry at Purdue University, carries out gas-phase studies of substituted aromatic radicals, biradicals, and polyradicals. By generating aromatic radicals which incorporate a positively charged group, Professor Kenttamaa is able to employ Fourier-transform ion cyclotron resonance mass spectrometry to examine their intrinsic or solvent-free reactivity under clean conditions, permitting the assessment of reaction rate constants, product branching ratios, and thermochemical parameters such as bond dissociation energies. Substituent effects are explored for phenyl, benzyl, and other aromatic mono- and polyradicals carrying neutral substituents in addition to the remote charged groups, and radical traps are employed to probe the importance of polar effects in different types of radical reactions. For biradicals, the relationship between reactivity and predicted ground state multiplicity is examined, and this information is used to search for spin-selective gas-phase reactions. Professor Hilkka I. Kenttamaa, of the Department of Chemistry at Purdue University, with the support of the Organic Dynamics Program and the Office of Multidisciplinary Activities of the Mathematical and Physical Sciences Directorate, studies the chemistry of molecules containing one or more unpaired electrons (`radicals`). By appropriate choice of radicals, Professor Kenttamaa is able to employ gas-phase techniques to study their formation and reactivity, permitting an assessment of their intrinsic properties in the absence of the complicating influences of solvents or other potentially reactive species. Through these studies is gained fundamental knowledge regarding the chemistry of electron-deficient molecules, advancing the understanding of the roles of substituent effects and polar effects in governing their reactivity and offering potential advances in the areas of radical-based organic synthesis and organic materials research.