Geometric and Electronic Structure Contributions to Bond-breaking and Bond-making Reactions of Mid-valent Manganese-Oxygen Complexes

在许多生物体中，重要的化学反应，如防御有毒自由基和DNA的生物合成，都是由需要金属锰的酶来执行的。要彻底了解这些酶的功能，需要了解化学反应过程中形成的中间产物。目前，科学家们对该酶如何在锰中心周围创造环境以控制特定中间体的反应活性的了解有限。在这个项目中，堪萨斯大学的蒂莫西·杰克逊教授正在使用合成化学来制作这些酶中间体的模型，目的是了解锰环境的特殊变化如何控制化学反应。需要确定这些系统的反应原理，以使科学家能够更好地了解锰酶的功能，并利用这些酶作为灵感来开发合成对应酶。杰克逊教授还积极参与为一门普通化学课程开发公共海报项目，该项目具有展示学生学习和提高公众科学素养的双重目的。该项目还提供独特的专业培训活动，让研究生和本科生参加联合的学术-工业会议和工作坊。在化学结构、动力学和机制B项目的资助下，堪萨斯大学的蒂莫西·杰克逊教授正在阐明管理MnIII-羟基和MnIII-烷基过氧基配合物的断键和成键反应的基本原理。这些络合物模拟了各种锰依赖酶机制中的中间体，包括锰超氧化物歧化酶和锰脂肪氧合酶。X射线衍射、X射线吸收、电子吸收和磁性圆二色谱方法与电子结构计算相结合，确定了MnIII-羟基和MnIII-烷基过氧基加合物的结构和电子性质，并确定了这些化合物的物理性质如何受到Lewis酸、氢键和/或支撑配体的变化的影响。采用实验和计算相结合的方法，建立了这些具有生物相关性的锰-氧中间体的新的结构-反应关系。杰克逊教授积极致力于将STEM教育和推广结合起来，通过将STEM推广项目纳入普通化学课程来提高公众的科学素养，以支持该项目的更广泛影响。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

In many organisms, important chemical reactions, such as defense against toxic free radicals and the biosynthesis of DNA, are performed by enzymes that require the metal manganese. A thorough understanding of the functions of these enzymes requires knowledge of intermediates formed during the chemical reactions. At present, scientists have a limited understanding of how the enzyme creates an environment around the manganese center to control the reactivity of particular intermediates. In this project, Professor Timothy Jackson of the University of Kansas is using synthetic chemistry to make models of these enzyme intermediates, with the goal of understanding how particular variations to the manganese environment control chemical reactivity. The identification of principles of reactivity for these systems are required to allow scientists to both better understand the function of the manganese enzymes and to use these enzymes as inspiration to develop synthetic counterparts. Professor Jackson is also actively engaged in developing public poster projects for a General Chemistry course that serve a dual purpose of displaying student learning and increasing public scientific literacy. This project also offers unique, professional training activities by having graduate and undergraduate students participate in joint academic-industrial meetings and workshops.With funding from the Chemical Structure, Dynamics, and Mechanisms B program, Professor Timothy Jackson of the University of Kansas is elucidating foundational principles governing the bond-breaking and bond-making reactions of MnIII-hydroxo and MnIII-alkylperoxo complexes. These complexes mimic intermediates proposed in the mechanisms of various manganese-dependent enzymes, including manganese superoxide dismutase and manganese lipoxygenase. X-ray diffraction, X-ray absorption, electronic absorption, and magnetic circular dichroism methods are combined with electronic structure computations to define structural and electronic properties of MnIII-hydroxo and MnIII-alkylperoxo adducts and determine how the physical properties of these complexes are modulated by Lewis acids, hydrogen-bonds, and/ or variations in supporting ligands. The combined experimental and computational approach is employed to develop new structure-reactivity relationships for these manganese-oxygen intermediates of biological relevance. Professor Jackson is actively engaged in combining STEM education and outreach by increasing public scientific literacy through the incorporation of STEM outreach projects in a General Chemistry course, in support of the broader impacts of this project.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.