FLP Zintl Clusters for the Electrochemical Catalytic Reduction of Small Molecules

用于小分子电化学催化还原的 FLP Zintl 簇

• 批准号: 2466112
• 金额: --
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2466112
• 关键词: FLP; Zintl; Clusters; Electrochemical; Catalytic

We will harness the untapped reactivity of Zintl ions, polayanionic clusters of earth abundant main-group elements, to affect small molecule activations in stoichiometric and catalytic fashions. Coupling reactions to yield new bonds, especially C-C bonds, occupy a central position in synthetic chemistry. To this end, a rich history of Pd cross-coupling reactions exploited by both academic and industrial chemists has developed. However, the high operational costs and toxicity of metal-based catalysts has spurred an interest in main-group systems that can represent this reactivity. Perhaps the most diverse and successful examples of main-group catalysts are frustrated Lewis pairs (FLPs). Traditional FLP systems rely on a Lewis acidic and a Lewis basic site to activate small molecules, and most homoatomic and heteroatomic bond formation reactions are accessed by bond polarisation mechanisms. However, the scope of these bond formation reactions remains limited and C-C bond formation with CO2 remains unidentified in the field. In this project, a new family of FLPs consisting of clusters capable of multi-site activation will be coupled with electrochemical methods to promote bond formation chemistries.We intend to establish Zintl clusters as the basic component in FLP chemistry. Preliminary investigations are targeted with [P7]3-, not only because of its synthetic accessibility, presence of an NMR handle, and greater stability relative to group 14 clusters, but also because of the wide-spread success of phosphines as the basic component in established FLP systems. Once functionalised with an acidic component, these polyanionic clusters are excellent targets for small molecule activation via a FLP pathway, as they feature both the necessary electron-rich and electron-poor components. With this proximity and the propensity to undergo redox reactions in mind, these systems will be assessed in the electrochemical reduction of small molecules, our most ambition target would be the selective reduction of CO2 to ethane. Recycling the C1 building-block, environmental toxin, and industrial by-product into value-added products reminiscent of the fuels from which CO2 is generated upon combustion.This research project will be collaboratively undertaken by the Mehta and Dryfe groups, and has been divided into two work packages.Work Package 1 (primarily based in the Mehta group):1. Functionalise the group 15 Zintl clusters, namely [P7]3-, with a Lewis acidic component2. Perform insertion chemistry between acidic and basic centres on these clusters akin to FLP chemistry. Small molecules of particular interest include CO2, olefins, carbonyls, carbodiimides, and isocyanates.PhD project call 20203. Reductively couple activated substrates to form new bondsWork Package 2 (primarily based in the Dryfe group):4. Immobilise FLP Zintl material on suitable electrode surfaces, e.g. glassy carbon or edge-plane pyrolytic graphite5. Electrochemically close catalytic cycles by reducing the expected oxidatively coupled cluster product6. Use kinetic analysis methods to determine, and optimise, rates of catalytic processes via fitting of electrochemical data.Zintl clusters capture the imagination of academics because they are molecular models for larger heterogenous systems. Technology we develop with [P7]3- can be expanded to larger polyphosphides, such as [P11]3-, [P16]2-, [P21]3-, and eventually inform reactivity possible with functionalised red phosphorus. The strategy of electrochemically / photochemically converting CO2 to reduced value-added products is referred to as artificial photosynthesis.

我们将利用锌离子的未开发反应性，锌离子是地球上丰富的主族元素的多阴离子簇，以化学计量和催化的方式影响小分子的激活。偶合反应产生新的键，特别是C-C键，在合成化学中占有重要地位。为此，学术和工业化学家都开发了丰富的钯交叉偶联反应的历史。然而，金属催化剂的高操作成本和毒性激发了人们对能够代表这种反应活性的主族系统的兴趣。也许最多样化和最成功的主基团催化剂的例子是受挫的刘易斯对(FLP)。传统的FLP系统依赖Lewis酸性和Lewis碱性位置来激活小分子，并且大多数同原子和异原子键的形成反应是通过键极化机制进行的。然而，这些成键反应的范围仍然有限，而且在该领域中仍未确定与二氧化碳形成C-C键。在这个项目中，一个由能够多位活化的簇合物组成的新的FLP家族将与电化学方法相结合来促进成键化学。我们打算建立锌簇合物作为FLP化学的基本成分。初步研究的目标是[P7]3-，这不仅是因为它的合成可及性、存在一个核磁共振手柄，以及相对于14族簇合物更稳定，而且还因为在已建立的FLP系统中，膦作为基本成分的广泛成功。一旦用酸性组分官能化，这些多阴离子簇就是通过FLP途径激活小分子的极佳目标，因为它们同时具有必要的富电子和贫电子成分。考虑到这种接近和进行氧化还原反应的倾向，这些系统将在小分子的电化学还原中进行评估，我们最雄心勃勃的目标将是选择性地将二氧化碳还原为乙烷。将C1积木、环境毒素和工业副产品回收到附加值产品中，使人想起燃烧时产生二氧化碳的燃料。这项研究项目将由Mehta和Dryfe小组合作进行，并已分为两个工作包。工作包1(主要基于Mehta组)：1.使15个锌离子簇功能化，即[P7]3-，具有Lewis酸性成分2。在这些簇上的酸性中心和碱性中心之间进行插入化学，类似于FLP化学。特别感兴趣的小分子包括二氧化碳、烯烃、羰基、碳二亚胺和异氰酸酯。博士项目电话20203。还原偶联活化的衬底以形成新的键工作包2(主要基于Dryfe组)：4.将FLP锌材料固定在合适的电极表面上，例如玻璃炭或边缘平面热解石墨石5。通过减少预期的氧化偶联簇合物6，在电化学上结束催化循环。使用动力学分析方法，通过对电化学数据的拟合来确定和优化催化过程的速率。锌簇合物吸引了学者的想象力，因为它们是更大的多相体系的分子模型。我们用[P7]3开发的技术-可以扩展到更大的聚磷化物，如[P11]3-，[P16]2-，[P21]3-，并最终用官能化红磷告知可能的反应性。通过电化学/光化学方法将二氧化碳转化为低附加值产品的策略被称为人工光合作用。