Catalytic photo-induced oxygen atom transfer using metal oxo complexes

背景：显然有必要开发能够最大限度地减少对有限能源的消耗并减少对环境有害的废物的工艺。在这种背景下，光催化显示出很大的前景，因为它允许利用光能通过电子或能量转移来驱动催化反应。在自然界和工业中，支撑许多过程的一个基本化学反应是氧原子转移。原则上，氧原子最清洁的来源是水和空气。然而，工业经常使用危险的过氧化氢或导致大量废物的金属氧化物，主要是因为可以利用水或空气的可行催化剂尚未得到充分开发。目的：我们的目标是开发利用生物灵感金属络合物的氧原子转移(OAT)催化剂，该催化剂可以被光激活。初步工作表明，OAT对配体结构非常敏感，催化循环中不止一个基本步骤需要光。该项目将研究机理的细节，并探索用于转化有用底物的燕麦反应的范围。实验方法：金属络合物合成和光催化将通过详细的结构和光谱研究来支持，以了解决定控制OAT过程的热力学和动力学现象的结构-性质关系。金属络合物的合成将包括开发具有光活性成分的多齿配体，以及使用能够支持活性金属氧合功能的过渡金属，如钼、钨和Re。蛋白质样本将由PDRA提供，他们正在为人造金属酶开发蛋白质支架。表征将包括单晶X射线衍射、核磁共振、红外、拉曼、紫外可见光谱和电化学。催化机理将使用时间分辨光谱进行研究，有可能利用国际设施进行超快研究。在合作中，还将使用密度泛函理论研究机械和光物理过程。新颖性：燕麦是一种基本的生物过程，尚未被用于化学合成。将水作为良性溶剂和氧源的光催化氧化技术将是一项重大的进步，将产生立竿见影的影响，并有可能广泛应用于清洁氧化。

Background: There is a clear need to develop processes that minimise the consumption of limited energy resources and reduce waste detrimental to the environment. In this context, photocatalysis is showing much promise since it allows light energy to be harnessed to drive catalytic reactions via electron or energy transfer. A fundamental chemical reaction that underpins many processes, both in nature and in industry, is oxygen atom transfer. In principle, the cleanest sources of oxygen atoms are water and air. However, industry often uses hazardous peroxides instead or metal oxides that lead to significant waste, primarily because viable catalysts that can use water or air are yet to be sufficiently developed. Objectives: Our aim is to develop oxygen atom transfer (OAT) catalysts using bioinspired metal complexes that can be activated by light. Preliminary work has shown that OAT is very sensitive to the ligand structure and that light is required for more than one fundamental step in the catalytic cycle. This project will investigate details of the mechanism and explore the scope of the OAT reaction for the conversion of useful substrates. Promising photocatalysts will be inserted into protein scaffolds to confer water solubility, biocompatibility and stereoselectivity.Experimental Approach: Metal complex synthesis and photocatalysis will be supported by detailed structural and spectroscopic studies to understand the structure-property relationships that determine thermodynamic and kinetic phenomena that control the OAT process. Metal complex synthesis will include the development of multidentate ligands with photoactive components and the use of transition metals, such as molybdenum, tungsten and rhenium, which can support reactive metal-oxo functionalities. Protein samples will be provided by PDRAs in the group who are developing protein scaffolds for artificial metalloenzymes. Characterisation will include single-crystal X-ray diffraction, NMR, IR, Raman, UV-Vis spectroscopies and electrochemistry. The catalytic mechanism will be studied using time-resolved spectroscopy with the potential to use international facilities for ultrafast studies. In collaboration, mechanistic and photophysical processes will also be studied theoretically using DFT. Novelty: OAT is a fundamental biological process that has not yet been exploited for chemical synthesis. Photocatalytic OAT using water as both benign solvent and oxygen source would be a significant advance that would have immediate impact and potentially wide application for clean oxidations.