Excited States of New Ru(II) Complexes: Controlling Reactivity

在这个由化学系化学结构、动态和机理B计划资助的项目中，俄亥俄州立大学化学和生物化学系的Claudia Turro教授与德克萨斯A&M大学的Kim Dunbar教授和休斯顿大学的Randolph Thummel教授合作，旨在了解过渡金属络合物吸收光子后非常早期(飞秒到皮秒)发生的步骤。这些研究在包括太阳能转换和光动力疗法在内的应用中具有重要意义。该项目还包括设计新的复合体，以更有效地释放更广泛的潜在药物，以及那些表现出双重反应的药物。当暴露在光线下时，这些络合物将有助于光释放“化学有效载荷”，并通过不同的机制影响细胞死亡。该项目结合了超快激光光谱学、合成和计算，因此非常适合各级科学家的教育。这个协作团队也处于有利地位，可以为科学方面代表性不足的学生提供最高水平的教育和培训。Ru(II)络合物在医学、工程和材料科学等众多科学领域有着广泛的应用。尽管[Ru(Bpy)3]2+(bpy=2，2‘-联吡啶)是用于这些领域的典型无机化合物，但相关配合物的超快激发态动力学和电子结构在大多数情况下仍然知之甚少。对于这些应用中的大多数，通过低位配位场(3LF)金属中心dd态的失活是不可取的，因为它减少了3MLCT(金属到配体电荷转移)激发态的发射和寿命。与之形成鲜明对比的是，光诱导药物释放的应用是为了增加具有如-L解离特性的3LF态(S)的布居。该项目的主要重点是了解管理光诱导配体交换的基本原理，最终目标是能够设计出具有更高配体交换产率的新系统，其主要元素是实现强配体的有效光释放，使用低能量可见光和近红外光，以及在激发后涉及多个路径。后一个目标提供了通过产生两个通过截然不同的机制起作用的活性物种，从而产生包含在单个分子中的“药物鸡尾酒”，从而显示出更高的生物活性的可能性。此外，获得的关于光诱导配体交换的基本知识也将有助于设计或合成需要取消配体交换过程以增加3MLCT态寿命的化合物。

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, in collaboration with Professor Kim Dunbar (Texas A&M University) and Professor Randolph Thummel (University of Houston), aims at understanding the steps that take place at very early times (femtosecond to picosecond) after a transition metal complex absorbs a photon of light. These studies are important in applications that include solar energy conversion and photodynamic therapy. The project also includes the design of new complexes that release a wider range of potential drugs more efficiently, as well as those that exhibit dual-reactivity. These complexes will be useful for the photo-release of "chemical payloads" when exposed to light and to effect cell death via different mechanisms. The project combines ultrafast laser spectroscopy, synthesis, and computation, and is therefore well suited to the education of scientists at all levels. This collaborative team is also well positioned to provide the highest level of education and training for students underrepresented in science. Ruthenium (II) complexes have been widely used in numerous areas of science, including medicine, engineering, and materials science. Despite the fact that [Ru(bpy)3]2+ (bpy = 2,2´-bipyridine) is the prototypical inorganic compound for use in these areas, the ultrafast excited state dynamics and electronic structure of related complexes remain, in most cases, poorly understood. For the majority of these applications, deactivation through the low-lying ligand-field (3LF) metal-centered dd states is undesirable, since it reduces the emission and lifetime of the 3MLCT (metal-to-ligand charge transfer) excited state. In sharp contrast, the application of photoinduced drug release is aimed at increasing the population of the 3LF state(s) with Ru-L dissociative character. The major focus of the project is to understand the basic principles that govern photoinduced ligand exchange with the ultimate goal of being able to design new systems with improved ligand exchange yields with the primary elements being to effect efficient photorelease of strong ligands, use low energy visible and near-IR light, and to involve multiple pathways following excitation. The latter goal provides the potential to exhibit increased biological activity by virtue of the production of two reactive species that act via vastly different mechanisms, thus producing a "drug cocktail" contained in a single molecule. Moreover, the basic knowledge gained regarding photoinduced ligand exchange will also 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.