CAS: CAREER: Synthetic Designs Toward Wavelength-Tunable Production of Reactive Intermediates for Selective Photooxidation

北卡罗莱纳大学格林斯博罗分校化学与生物化学系的Shabnam Hematian在化学系化学结构、动力学与机理B项目的支持下，致力于开发一种新型光催化剂，将廉价和不活泼的原料转化为增值化学品。这些潜在的催化剂利用空气中氧的氧化能力，作为一种绿色末端氧化剂，和光的能量作为一种可持续的试剂，形成新的和难以接近的化学键。本研究的目的是通过调节光源的能量来控制光化学结果和反应选择性。该项目的结果有可能实现与药物和其他精细化学品合成相关的更快和可调的反应。这项工作为各级科学家在光化学、合成、光谱学、氧化还原和动力学等领域提供了坚实的跨学科培训平台。这个群体也处于有利地位，可以提供最高水平的教育和培训，让学生在职业生涯的早期参与科学（即当地高中和社区大学的学生，以及一年级本科生和研究生），促进化学领域的招聘和保留。在温和条件下以双氧作为末端氧化剂选择性氧化底物的有效均相光催化剂的发现仍然是合成化学的一个重要目标。提出的工作旨在设计和开发一类新的光催化剂，其中金属-双氧化学导致双氧的协同活化和氧桥异双核系统的形成。在开发的体系中，两种不同的活性高价金属-氧中间体可以通过两个独特的由电荷转移激发态驱动的金属-氧键的光激活来获得。在本项目中，将研究已开发的氧桥接结构的结构-功能关系，以了解通过基态氧桥接配体在单个催化位点之间的电子交换耦合如何以及在多大程度上影响电荷转移转变，以及这种耦合如何在整体光活性中表现出来。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。

With support from the Chemical Structure, Dynamics & Mechanisms B Program of the Chemistry Division, Shabnam Hematian of the Department of Chemistry and Biochemistry at the University of North Carolina at Greensboro aims to develop a new class of photocatalysts to transform cheap and unreactive raw materials into value-added chemicals. These potential catalysts exploit the oxidizing power of oxygen in the air, as a green terminal oxidant, and the energy of light as a sustainable reagent for forming new and difficult-to-access chemical bonds. The goal of this research is to control the photochemical outcome and reaction selectivity through modulating the energy of the light source. Results from this project have the potential to enable faster and tunable reactions which are relevant in the synthesis of pharmaceuticals and other fine chemicals. This work provides a solid interdisciplinary training platform in the fields of photochemistry, synthesis, spectroscopy, redox, and kinetics for scientists at all levels. This group is also well-positioned to provide the highest level of education and training to engage students in science early in their careers (i.e., local high school and community college students as well as first-year undergraduate and graduate students), promoting recruitment and retention in the chemistry field. The discovery of effective homogeneous photocatalysts for the selective oxidation of substrates under mild conditions using dioxygen as the terminal oxidant remains an important objective in synthetic chemistry. The proposed work seeks to design and develop a new class of photocatalysts in which metal-dioxygen chemistry leads to the cooperative activation of dioxygen and formation of oxo-bridged heterobinuclear systems. In the developed systems, two different reactive high-valent metal-oxo intermediates are accessible through the photoactivation of two unique metal-oxo bonds which are driven from charge transfer excited states. In this project, the structure-function relationships of the developed oxo-bridged constructs will be investigated to understand how and to what extent electronic exchange coupling between the individual catalytic sites through an oxo bridging ligand in the ground state impacts the charge transfer transitions and how this coupling manifests itself in overall photoactivity.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.