Metal-Catalyzed Diradical Reactivity: From Fundamental Thermal- and Photo-Chemistry to Novel Nanomaterials

在一个名为“金属催化的双自由基反应：从基础热化学和光化学到新型纳米材料”的项目中，化学催化(CAT)项目支持印第安纳大学的Jeffrey M.Zaleski教授探索控制伯格曼环化反应中金属催化和光化学双自由基生成的几何和电子因素。研究了三种主要的结构类型：1)通过sigma键几何控制和通过pi-体系电子控制活化的sigma/pi复合体。这一主题考察了催化Bergman环化途径与Myers-Saito环化途径的结构，这些途径对自由基介导的化学转化非常重要；2)构建大型发色组件，使用热和光化学Bergman环化反应来催化熔合环系统，形成光学响应分子；以及3)将这些反应性配体集结合到大的纳米组件中，这些大的纳米组件可以被激活，通过模板蒸发形成所有的碳骨架。这三个体系结构类既包含需要解决的基本研究问题，也包含来自最终体系结构和反应的潜在更广泛影响。热反应路径使用标准合成方法，如核磁共振、结晶学和反应中间产物的光谱表征进行评估。发色产物的光学性质主要通过纳秒、超快寿命和瞬时吸收等方法来检测，而纳米结构的表征主要是通过电子显微镜进行的。这项研究影响了利用金属/自由基介导的反应构建新分子的化学催化方法，这是化学界的基本需求。这项工作的发色团组件构建了新的结构，可用作化学传感器，或用于太阳能转换中的光收集。该项目的纳米材料方面在纳米尺度的表面上产生反应，以创造新的、更高阶的组装，这些组装在分子电子和超轻纯碳电子阵列中具有潜在的应用。从教育的角度来看，这项研究有助于培训学生采用基础科学/化学应用相结合的方法，这种方法跨越了合成和高科技测量。所有级别的学生，从本科生到博士后，包括那些来自伊利诺伊大学代表性不足的少数民族项目的学生，都受益于一系列研究挑战和多样化的解决方案。一些工作被外包给当地的学校，以吸引年轻人攻读理科学位。

In a project entitled "Metal-Catalyzed Diradical Reactivity: From Fundamental Thermal- and Photo-Chemistry to Novel Nanomaterials," the Chemical Catalysis (CAT) program supports Professor Jeffrey M. Zaleski at Indiana University to probe the geometric and electronic factors that control metal-catalyzed and photochemical diradical generation by the Bergman cyclization. Three primary structure types are investigated: 1) combined sigma/pi complexes where activation is geometrically controlled through the sigma bonds and electronically via the pi-system. Structures in this theme examination of catalytic Bergman vs. Myers-Saito cyclization pathways that are important to radical-mediated chemical transformations; 2) construction of large chromophoric assemblies that use thermal and photochemical Bergman cyclizations to fuse ring systems catalytically to form optically responsive molecules; and 3) incorporation of these reactive ligand sets into large nanoassemblies that can be activated to form all carbon frameworks by template vaporization. These three architectural classes carry both a fundamental research question to be addressed as well as a potential broader impact from the final architectures and reactions. Thermal reaction pathways are evaluated using standard synthetic methodology such as NMR, crystallography, and spectroscopic characterization of reaction intermediates. Optical properties of chromophoric products are examined using nanosecond and ultrafast lifetime and transient absorption methods, while characterization of nanoarchitectures is conducted mainly using electron microscopy.This research impacts chemical catalysis methodology for constructing new molecules using metal/radical mediated reactions, which is a fundamental need in the chemical community. The chromophore assembly component of the work builds new constructs that can be used as chemical sensors, or for light harvesting in solar energy conversion. The nanomaterial aspect of the project generates reactions on nanoscale surfaces to create new, higher-order assemblies that have potential applications in molecular electronics and ultralight pure carbon electronic arrays. From an educational perspective, the research helps to train students in a combined fundamental science/application approach to chemistry that spans synthesis and high-tech measurements. Students at all levels from undergraduate to postdoctoral, including those from underrepresented minorities programs at IU, benefit from exposure to a range of research challenges and diversities of solution. Some of the work is outreached to local schools to entice young minds to pursue degrees in science.