Controlling the Rates, Distance, and Direction of Electron Transfer in Ultrafast Inorganic Ground States

在这个由化学部门化学结构、动力学和机制B项目资助的项目中，加州大学圣地亚哥分校化学和生物化学系的Clifford Kubiak教授正在开发新的金属配合物组装，这些金属配合物可以进行快速电子转移（ET）反应。这些反应由红外光谱监测，具有皮秒（1万亿分之一秒）的时间分辨率来跟踪这种超快反应。这些研究的目标是对决定ET反应速率、距离和方向的化学因素有一个基本的了解。这项工作可能最终为分子电子器件的设计铺平道路，如开关和存储器，其功能远远快于当前一代的计算机和传感器。该项目处于合成化学和物理表征的交叉点，为培养研究生和本科生的前沿研究提供了丰富的机会。控制电子转移的速率、距离和方向对生命科学、技术和能源部门有着广泛的影响。该项目代表了基础研究，但如果成功，最终可能在重要领域造福社会，包括治疗由DNA损伤引起的遗传疾病；新一代更快、更小、更便宜的集成电路；人工和自然光合作用的进展与农业粮食生产的改进。库比亚克教授让本科生参与研究，也让K-14年级的学生参与。该小组与加州州立大学蒙特利湾分校（CSUMB）建立了一个新的本科生交换项目，学生可以在暑假和学校休息期间在CSUMB和UCSD进行部分研究项目。该研究小组还开发了复杂科学思想的可视化，他们的视频也被研究人员、教育工作者和公众广泛分享。醋酸三钌簇的混合价二聚体显示了远距离超快ET的丰富光谱证据。它们已经被证明是富有成效的系统，可以说明不同的桥接部分、电子结构、化学环境和动力学如何影响ET的动力学障碍。Clifford Kubiak教授和他的团队计划开发更完整的物理化学描述，描述电子如何在氢键之间转移。他们将扩大新的配合物的合成，以更好地了解电子离域和氢键之间的相互作用。此外，他们将在皮秒时间尺度上对分子内ET进行第一次二维红外光谱（2D-IR）研究。他们将使用合成研究来探索桥接配体动力学及其与ET的关系。本研究将试图证明ET坐标的振动控制以改变其速率和方向。最后，该团队将设计和合成新的超分子组件，通过半导体金属氧化物纳米颗粒在垂坠的三钌氧化还原中心之间表现出混合价。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In this project, funded by the Chemical Structure, Dynamics, and Mechanisms B Program of the Chemistry Division, Professor Clifford Kubiak of the Department of Chemistry and Biochemistry at the University of California San Diego is developing new assemblies of metal complexes that undergo fast electron electron transfer (ET) reactions. These reactions are monitored by infrared spectroscopy which has picosecond (1 trillionth of a second) time resolution to follow such ultrafast reaction. The goal of these studies is to develop a fundamental understanding of the chemical factors that determine the rate, distance, and direction of ET reactions. This work may ultimately pave the way towards the design of molecular electronic devices such as switches and memory that function far faster than the current generation of computers and sensors. This project lies at the intersection between synthetic chemistry and physical characterization, providing a rich opportunity for the training of graduate and undergraduate students in cutting-edge research. Controlling the rates, distance, and direction of electron transfer broadly impacts the life sciences, technology, and energy sectors. This project represents basic research but, if successful, could ultimately benefit society in important areas including treatments for genetic disorders caused by damage to DNA; a new generation of faster, smaller, and less expensive integrated circuits; advances in artificial and natural photosynthesis and improvements in agricultural food production. Professor Kubiak involves undergraduate students in research and engages K-14 students. The group has established a new undergraduate exchange program with Cal State University Monterey Bay (CSUMB) for students to pursue research projects that can be performed partly at CSUMB and partly at UCSD during summers and school breaks. The research team also develops visualizations of complex scientific ideas and their videos are also being shared broadly with both researchers, educators and the general public. Mixed-valence dimers of triruthenium acetate clusters display rich spectroscopic evidence of ultrafast ET over long distances. They have proven to be fruitful systems in illustrating how different bridging moieties, electronic structures, and chemical environments and dynamics can impact the kinetic barriers of ET. Professor Clifford Kubiak and his group plan to develop a more complete physical chemical description of how electron transfer occurs across hydrogen bonds. They will expand the synthesis of new complexes to better understand the interplay between electron delocalization and hydrogen bonding. Additionally, they will conduct the first two-dimensional infrared spectroscopy (2D-IR) studies of intramolecular ET on the picosecond timescale. They will use synthetic studies to probe bridging ligand dynamics and its relation to ET. This research will attempt to demonstrate vibrational control of the ET coordinate to change its rate and direction. Finally, the team will design and synthesize new supramolecular assemblies that exhibit mixed valency between pendant tri-ruthenium redox centers through semiconducting metal oxide nanoparticles.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.