Surface Supported Frustrated Lewis Pairs (FLPs) for Small Molecule Activation and Catalysis

催化剂是通过降低反应发生所需的能量来加速反应的物质。虽然我们在日常生活中不一定经常想到它们，但它们就在我们身边；从汽车排气管中的催化转换器减少有毒物质的排放，到促进我们体内生命必需代谢过程的酶。催化转化器是多相催化剂的一个例子，即产物与催化剂处于不同的物理状态，而酶被认为是均相催化剂——产物和催化剂处于相同的状态（通常都是液体）。在现代世界中，我们所依赖的许多工业系统都使用一组被称为过渡金属的元素作为均相催化剂。就像牛奶在混合后很难从茶中分离出来一样，从产品混合物中去除均相催化剂也是一个相当大的挑战。这是进一步复杂的事实，即使是少量的残余金属是一个非常不希望的污染物在应用中，特别是医药。在过去的14年里，一种被称为FLPs（受挫刘易斯对）的化合物家族被开发出来，作为传统催化剂的无过渡金属替代品。FLPs最初引起了人们的注意，因为它们能够可逆地分裂氢原子之间的强键（称为激活氢）。打破这个键是氢催化的先决条件，因此研究这些活化过程对催化剂设计至关重要。换一种说法，氢激活，想象一下在你身体的休息状态下，你的手掌被超级粘在一起。只有当胶封被某种物质冲走时，你才能拿起许多不同的东西，而不是被限制在另一只手掌上。现在，想象一下，在捡起物品并根据你的愿望修改它们之后，你可以使用洗涤物质一次又一次地随意重建和打破密封。这本质上是氢活化的过程，你的手是氢原子，洗手是FLP。想想你能用双手完成多少不同的重要任务——突然间，一个类似的化学过程似乎很重要。虽然氢分裂的主要工作集中在均相系统上，但尝试创建异相FLPs正变得越来越普遍，因为这将解决获得纯产物的两个问题：从催化剂中分离和金属杂质的存在。在这个项目中，我们将首先专注于扩大我们对具有潜在催化能力的FLP的理解。然后，我们的目标是将其附着在称为LDH（层状双氢氧化物）的表面支撑物上，使系统异构。之所以选择ldh作为表面，是因为它们已经得到了很好的研究，而且很容易制造。该项目属于EPSRC的“制造未来”研究领域。

Catalysts are substances which speed up reactions by lowering the amount of energy required for them to occur. Whilst we don't necessarily think about them often in everyday life, they are all around us; from catalytic converters in car exhaust pipes reducing toxic emissions, to enzymes facilitating life essential metabolic processes in our bodies. A catalytic converter is an example of a heterogeneous catalyst i.e. one where the products are in a different physical state to the catalyst, whilst enzymes are considered homogeneous catalysts - the products and the catalyst are in the same state (usually both liquids). Many of the industrial systems we rely upon in the modern world employ a group of elements known as the transition metals as homogeneous catalysts. In much the same way as it would be difficult to separate the milk from your tea once mixed, removing homogeneous catalysts from the product mixture is a considerable challenge. This is further complicated by the fact that even a small amount of residual metal is a highly undesirable contaminant in applications, especially medicine. In the past 14 years, a family of compounds known as FLPs (Frustrated Lewis Pairs) have been developed as transition metal free alternatives to traditional catalysts. FLPs initially caught attention due to their ability to reversibly split the strong bond between hydrogen atoms (referred to as activating hydrogen). Breaking this bond is a prerequisite for catalysis using hydrogen so investigation of these activation processes is vital for catalyst design. To put hydrogen activation in different terms, imagine that in your body's resting state the palms of your hands are superglued together. Only if the glue seal is washed away with some substance are you able to pick up many different objects rather than be constrained to the other palm. Now, imagine that after picking up objects and modifying them to your desires, you are able to recreate and break the seal at will over and over again using the washing substance. This is essentially the process of hydrogen activation where your hands are the hydrogen atoms and the wash an FLP. Think about how many different vital tasks you are able to complete with your hands - suddenly an analogous chemical process seems important. Whilst the main body of work on hydrogen splitting has focussed on homogenous systems, attempts to create heterogeneous FLPs are becoming more common as this would solve both issues with obtaining pure product: separation from catalyst and presence of metal impurities. In this project, we will first focus on broadening our understanding of an FLP which has potential catalytic capability. We will then aim to attach it to a surface support called an LDH (Layered Double Hydroxide) to make the system heterogeneous. LDHs have been chosen as the surface as they have been well studied and are easily made. This project falls within the EPSRC 'manufacturing the future' research area.