Control of Excited State Dynamics of Ru(II) Complexes for Dual Activity

在这个项目中，由化学部门化学结构、动力学和机制B项目资助，俄亥俄州立大学化学和生物化学系的Claudia Turro与德克萨斯州农工大学的Kim Dunbar和韦恩州立大学的Jeremy Kodanko合作，旨在了解过渡金属配合物在很早的时候（飞秒到皮秒范围内）吸收光的光子后发生的步骤。这些金属配合物的应用包括太阳能转换和光动力治疗药物的输送。该项目还将侧重于设计新的复合物，通过低能量可见光到近红外光的照射，释放更广泛的配体，特别是那些强协调的配体。一个主要目标是研究具有双重反应性的配合物。获得的关于光诱导配体交换的基本知识将有助于设计需要消除配体交换过程的配合物，以增加金属到配体电荷转移（3MLCT）态的寿命，这是太阳能转换中的一个重要因素。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。该项目的主要目标是了解Ru（II）配合物早期光物理过程的基本原理。重点是控制有效光取代的因素，以及双活性化合物。这些物质产生细胞毒性单线态氧并进行配体交换。两种不同的光活性态在这些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。此外，Ru（II）配合物的光诱导药物释放高度依赖于离去配体和辅助配体的身份，这一点将被研究。假设金属中心三重态配体场（3LF）的快速填充是配体交换发生的必要条件，但目前尚不清楚配体交换是否也直接发生在最低能量的3MLCT（三重态金属到配体的电荷转移）态。关于光诱导配体交换的基本知识将有助于设计或配合物，这些配合物需要消除配体交换过程，以增加3MLCT状态的寿命，这是太阳能转换中的一个重要因素。建议的研究包括电子和振动超快光谱研究，以及合成新的配合物，以改善配体解离和双重作用。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 & Mechanisms B Program of the Chemistry Division, Claudia Turro of the Department of Chemistry and Biochemistry at Ohio State University, in collaboration with Kim Dunbar at Texas A&M University and Jeremy Kodanko at Wayne State University, aims at understanding the steps that take place after a transition metal complex absorbs a photon of light at very early times--in the femtosecond to picosecond domain. Applications of these metal complexes include solar energy conversion and the delivery of drugs for photodynamic therapy. The project will also focus on the design of new complexes that release a wider range of ligands, especially those that coordinate strongly, through irradiation with low energy visible to near-infrared light. One major goal is the investigation of complexes that exhibit dual-reactivity. The basic knowledge gained regarding photoinduced ligand exchange will aid in the design of complexes that require the ligand exchange process to be eliminated in order to increase the lifetime of the triplet metal-to-ligand charge transfer (3MLCT) state, a factor important in solar energy conversion. This collaborative team is also well positioned to provide the highest level of education and training for students underrepresented in science. The major goal of this project is to understand the basic principles governing photophysical processes in Ru(II) complexes at early times. Focus is on the factors that control efficient photosubstitution, as well as dual-activity compounds. These substances generate cytotoxic singlet oxygen and also undergo ligand exchange. The mechanism by which two different photoactive states are populated in these complexes remains unknown and is counter to the rules of photochemistry developed for organic molecules. In addition, photoinduced drug release using Ru(II) complexes is highly dependent on the identity of both the leaving and ancillary ligands, a point that will be investigated. It is hypothesized that fast population of the metal-centered triplet ligand field (3LF) state is required for ligand exchange to take place, but it is yet unknown if ligand exchange also occurs directly from the lowest-energy 3MLCT (triplet metal-to-ligand charge transfer) state. The basic knowledge gained regarding photoinduced ligand exchange will aid in the design or complexes that require the ligand exchange process to be eliminated in order to increase the lifetime of the 3MLCT state, a factor important in solar energy conversion. The proposed research includes electronic and vibrational ultrafast spectroscopic studies, as well as the synthesis of new complexes for improved ligand dissociation and for dual action.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.