Catalytic photo-induced oxygen atom transfer using metal oxo complexes

背景资料：显然需要开发使有限能源的消耗最小化并减少对环境有害的废物的方法。在这种情况下，光催化剂显示出很大的希望，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，支撑许多过程的基本化学反应是氧原子转移。原则上，最清洁的氧原子来源是水和空气。然而，工业界经常使用危险的过氧化物或金属氧化物，这导致大量废物，主要是因为可以使用水或空气的可行催化剂尚未得到充分开发。目的：我们的目标是开发氧原子转移（OAT）催化剂，使用生物启发的金属配合物，可以被光激活。初步工作表明，OAT是非常敏感的配体结构，光是需要在催化循环中的一个以上的基本步骤。本项目将研究该机制的细节，并探索OAT反应转化有用底物的范围。有前途的光催化剂将被插入到蛋白质支架中，以赋予其水溶性、生物相容性和立体选择性。实验方法：金属络合物的合成和表征将得到详细的结构和光谱研究的支持，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。金属络合物合成将包括开发具有光活性组分的多齿配体和使用过渡金属，如钼、钨和铼，它们可以支持反应性金属-氧代官能团。蛋白质样品将由正在为人工金属酶开发蛋白质支架的小组中的PDRA提供。表征将包括单晶X射线衍射、NMR、IR、拉曼、紫外-可见光谱和电化学。将使用时间分辨光谱学研究催化机制，并有可能使用国际设施进行超快研究。在合作中，机械和物理过程也将使用DFT理论研究。新奇：OAT是一种基本的生物过程，尚未用于化学合成。使用水作为良性溶剂和氧源的光催化OAT将是一个显著的进步，其将对清洁氧化具有直接影响和潜在的广泛应用。

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.