Hydrogen Atom Transfer Reactivity of Unsymmetric Bimetallic Complex

在化学系化学结构、动力学和机理B计划(CSDM-B)和化学合成计划(SYN)的支持下，俄亥俄州立大学化学系的张世宇正在开发模型化合物，以阐明不等价环境对天然蛋白质中双金属中心反应活性的影响。这项研究的目标是弥合金属酶和旨在模拟酶功能的合成催化剂之间的差距，并揭示对能源、健康和环境科学至关重要的催化剂的新设计策略。研究活动将与本科生和研究生的培训相结合，通过结合合成无机、光谱和理论方法来应对跨学科的挑战。涉及K-12学生的外展活动也将是该资助项目的一部分。在本项目中，将制备两类新的双金属配合物，以再现自然界中普遍存在的双金属活性中心的不对称特征，例如：(I)不等价的二次配位球，(Ii)不等价的一次配位球，(Iii)不对称的金属结合(异双金属中心)。将开发新的方法来量化双金属的分化程度，并建立一套衡量标准(氢原子转移动力学、金属亲和力等)。帮助定义成功，目标是提高我们对感兴趣的金属酶的理解。在目标1中，将合成在主次配位球上具有不等价特征的双铜模型络合物，以了解位置分化的程度是否与氢原子转移速度相关。在目标2中，将开发仿生异质双金属FeMn络合物，以了解合成FeMn络合物的形成。将比较等结构的FeMn、FeFe和MnMn双金属络合物对氧活化和氢原子转移的反应性，以了解异双金属活性中心的进化影响。这一奖项反映了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。

With support from the Chemical Structure, Dynamics & Mechanisms-B Program (CSDM-B) and the Chemical Synthesis (SYN) Program of the Chemistry Division, Shiyu Zhang of the Department of Chemistry at Ohio State University is developing model complexes to elucidate the influence of inequivalent environment on the reactivity of bimetallic centers in natural proteins. The goal of this research is to bridge the gap between metalloenzymes and synthetic catalysts designed to mimic enzymatic functions and unveil new design strategies for catalysts fundamental to energy, health, and environmental science. The research activities will be integrated with the training of undergraduate and graduate students in addressing interdisciplinary challenges with a combination of synthetic inorganic, spectroscopic, and theoretical methods. Outreach activities involving K-12 students will also be part of the funded project. In this project, two classes of new bimetallic complexes will be prepared to reproduce ubiquitous unsymmetric features of bimetallic active sites in nature, e.g., (i) inequivalent secondary coordination sphere, (ii) inequivalent primary coordination sphere, and (iii) unsymmetric metal binding (heterobimetallic center). New methods will be developed to quantify the degree of bimetallic differentiation and establish a set of metrics (hydrogen atom transfer kinetics, metal affinity, etc.) to help define success with the goal of improving our understanding of the metalloenzymes of interest. In Aim 1, dicopper model complexes with inequivalent features at the primary and secondary coordination sphere will be synthesized to understand if the degree of site-differentiation correlates with the rate of hydrogen atom transfer. In Aim 2, biomimetic heterobimetallic FeMn complexes will be developed to understand the formation of synthetic FeMn complexes. The reactivity of isostructural FeMn, FeFe, and MnMn bimetallic complexes toward oxygen activation and hydrogen atom transfer will be compared to understand the evolutionary implications of heterobimetallic active sites.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.