Organofunctionalisation of Polyoxometalates for Photocatalysis

该合作研究项目的基本目标是开发合成方法，以便从简单，易得的起始材料有效构建医学相关化合物。在这方面，该项目涉及设计和合成可用于合成有机反应的新型光催化剂。与传统方法（如加热）相比，利用光来促进反应性可以被视为一种更可持续和更经济的能源，并可用于克服显着的反应障碍。有机光氧化还原化学中最常用的催化剂涉及由铱、铑或钌组成的过渡金属络合物。然而，这些铂族金属是稀有的、昂贵的，并且通常需要预官能化的起始材料来进行反应。近年来，避免这些金属的催化剂的开发在该领域显示出了希望。然而，这些催化剂具有局限性，包括低选择性和需要高能UV光。此外，使用这些催化剂开发的反应可能产率低，范围有限，并显示出竞争性的产物分解。在该领域取得进展的关键是开发新型可见光响应性光催化剂，其可以被改性以（i）提高催化效率，（ii）表现出额外的功能-其可以用于促进催化剂分离和/或再循环，以及（iii）增加反应速率和产率。这引发了对可用于合成有机反应的更可持续，可调和选择性可见光活性光催化剂的驱动。在有机反应类型方面，本项目将特别关注光催化C-H功能化。通过C-H键官能化的偶联涉及使用简单的底物，这些底物直接转化为更复杂的分子，而不需要预先官能化，从而大大减少了废物的产生和所需的合成步骤的数量。通过将C-H功能化和光氧化还原催化相结合，可以将已建立的合成方法应用并纳入药物发现中，作为结构-活性关系（SAR）探索和后期功能化的一部分。建议的解决方案和方法成功设计和合成各种光活性催化剂构成了该项目的基础。我们努力合成的催化剂类型由用各种有机配体官能化的核心结构组成。通过精心设计，我们的目标是研究不同的配体对催化剂的光催化性能的影响，同时考虑到对选择性，产率，催化回收和进行的反应的效率的影响。在展示了光催化剂的催化性能并深入了解了催化剂的化学反应性和适用性之后，该项目的下一个目标是开发充分利用催化剂的新方法。这些目标的成功完成首先将推进现有的反应，这些反应具有先前使用的特定催化剂所固有的局限性，其次，将提供目前未知或无法获得的反应途径，允许简单的有机底物在温和和有效的反应条件下转化为复杂的结构。

The fundamental goal of this collaborative research project is the development of synthetic methodologies that will allow for the efficient construction of medicinally relevant compounds from simple, readily available starting materials. In this context, the project involves the design and synthesis of novel photocatalysts that can be exploited in synthetic organic reactions. Harnessing light to promote reactivity can be viewed as a more sustainable and economic energy source when compared to conventional methods such as heat and can be used to overcome significant reaction barriers. The most used catalysts in organic photoredox chemistry involve transition-metal complexes comprised of iridium, rhodium, or ruthenium. However, these platinum-group metals are rare, expensive, and usually require pre-functionalised starting materials for the reactions to proceed. In recent years, the development of catalysts that avoid these metals have shown promise in this field. However, these catalysts have limitations including low selectivity and the requirement of high energy UV-light. Furthermore, the reactions developed using these catalysts can be low yielding, be limited in scope and display competitive product decomposition. Crucial to progressing in this area is the development of novel visible light responsive photocatalysts that can be modified to (i) enhance the catalytic efficiency, (ii) exhibit additional functionality - that can be used to facilitate catalyst isolation and/or recycling, and (iii) increase the reaction rates and yield. This has sparked the drive towards more sustainable, tuneable, and selective visible-light active photocatalysts that can be used in synthetic organic reactions. In terms of organic reaction types, particular attention will be focused on photocatalytic C-H functionalisation for this project. Couplings through C-H bond functionalisation involves the use of simple substrates that are directly converted into more complex molecules, without the need of a previous functionalisation, thus considerably reducing waste generation and the number of synthetic steps required. By combining C-H functionalisation and photoredox catalysis, established synthetic methodology could be applied and incorporated into drug discovery, as part of structure-activity relationship (SAR) exploration and late-stage functionalisation. Proposed solution and methodologyThe successful design and synthesis of a variety of photoactive catalysts forms the basis of this project. The type of catalyst we endeavour to synthesise consists of a core structure functionalised with a variety of organic ligands. By careful design, we aim to investigate the effect of different ligands on the photocatalytic performance of the catalyst, taking into consideration the effects on selectivity, yield, catalytic recycling, and efficiency of the reactions conducted. After the demonstration of the catalytic performance of the photocatalysts and insight is gained into the chemical reactivity and applicability of the catalysts, the next aim of the project involves the development of novel methodology exploiting the catalysts to their full potential. The successful completion of these aims will firstly advance existing reactions that have limitations inherent with the specific catalysts used previously, and secondly, will provide access to currently unknown or inaccessible reaction routes, allowing simple organic substrates to be converted into complex structures, under mild and efficient reaction conditions.