Design of New Ru(II) Complexes to Control Excited State Reactivity

在这个由化学部门化学结构、动态和机制B项目资助的项目中，俄亥俄州立大学化学和生物化学系的Claudia Turro教授与Kim Dunbar教授（德州农工大学）和Jeremy Kodanko教授（韦恩州立大学）合作研究无机光化学的基本过程。该项目旨在了解过渡金属配合物吸收光的光子后，在超快（飞秒到皮秒）时间尺度上发生的基本步骤。设计、合成和研究了新的钌配合物，以确定它们的激发态过程和光化学如何依赖于结构的变化。在这项研究中研究的过渡金属配合物在从太阳能转换到光疗药物输送的应用中具有重要意义。这个合作团队也有能力为在科学领域代表性不足的学生提供最高水平的教育和培训。该项目的中心目标是了解早期控制钌II配合物光物理过程的基本原理，包括控制有效光取代和双活性化合物的因素。设计、合成和研究新的钌配合物，以测试结构变化如何影响光化学和光物理的理论。两种不同的光活性态在这些钌配合物中填充的机制仍然未知，并且与有机分子开发的光化学规则相反。钌II配合物的光诱导配体释放高度依赖于离去配体和辅助配体的身份。解释这种结构依赖性的一个假设是，金属中心配体场态的快速填充是配体交换发生的必要条件。目前尚不清楚这是通过单线态流形或振动热三重态的直接系统间交叉发生的。获得的关于光诱导配体交换的基本知识也有助于设计消除交换过程的配合物，以增加金属到配体的电荷转移状态的寿命。这是太阳能转换的一个重要因素。该项目还侧重于设计和合成新的配合物，通过可见光或低能量近红外光照射释放更大范围的配体。本研究研究的过渡金属配合物在太阳能转换和光治疗等方面具有潜在的应用前景。这项合作研究为学生提供了多种研究技能的培训。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, Dynamic & Mechanism B Program of the Chemistry Division, Professor Claudia Turro of the Department of Chemistry and Biochemistry at The Ohio State University works in collaboration with Professor Kim Dunbar (Texas A&M University) and Professor Jeremy Kodanko (Wayne State University) investigate fundamental processes in inorganic photochemistry. This project seeks to understand the fundamental steps that take place on ultrafast (femtosecond to picosecond) time scales after a transition metal complex absorbs a photon of light. New ruthenium complexes are designed, synthesized and studied to determine how their excited state processes and photochemistry depend on variation in structure. Transition metal complexes studied in this research are important in applications that range from solar energy conversion to the delivery of drugs for phototherapy. This collaborative team is also well positioned to provide the highest level of education and training for students underrepresented in science.The central goal of this project is to understand the basic principles that govern the photophysical processes in ruthenium II complexes at early times, including the factors that control efficient photosubstitution and dual-activity compounds. New ruthenium complexes are designed, synthesized and studied to test theories about how variation in structure affects photochemistry and photophysics. The mechanism by which two different photoactive states are populated in these ruthenium complexes remains unknown and is counter to the rules of photochemistry developed for organic molecules. Photoinduced ligand release using ruthenium II complexes is highly dependent on the identity of both the leaving and ancillary ligands. One hypothesis being tested to explain this structural dependence is that fast population of the metal-centered ligand field state is required for ligand exchange to take place. It is yet unknown if this occurs through direct intersystem crossing from the singlet manifold or from a vibrationally hot triplet state. The basic knowledge gained regarding photoinduced ligand exchange also aids in the design of complexes that eliminate the exchange process in order to increase the lifetime of the metal-to-ligand charge transfer state. This is an important factor in solar energy conversion. The project also focuses on the design and synthesis of new complexes that release a wider range of ligands through irradiation with visible or low energy near-infrared light. Transition metal complexes studied in this research have potential applications that include solar energy conversion and phototherapy. This collaborative research provides students with training in diverse research skills.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.