Dynamic Mechanically Interlocked Rotaxane and Catenane Catalysts for Isoselective Ring Opening Polymerisation

用于同选择性开环聚合的动态机械联锁轮烷和链烷催化剂

• 批准号: 2329690
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2329690
• 关键词: Dynamic; Mechanically; Interlocked; Rotaxane; Catenane

Polymers consist of long chains comprised from many repeating smaller molecules, known as monomers. Essential in modern life, polymeric materials have extensive applications such as clothing, electronics and medicine, as their desired physical and chemical properties can be engineered by careful monomer selection. However, many polymeric materials are produced from non-renewable monomers and are non-biodegradable, raising serious environmental concerns over their future manufacture and disposal. Consequently, there is mounting public and academic interest in developing more environmentally sustainable routes to biodegradable polymers.Polymer production requires catalysts, most commonly containing metals, to affect regulated linking of the monomer units to form the polymer chain. The environment of the metal in the catalyst, dictated by the arrangement of atoms surrounding it, plays a key role in specifying catalyst performance and selectivity. Such control is essential to form materials with well-defined properties, such as strength and temperature resistance, crucial for any given application.Recent studies demonstrated that incorporating a metal into complex molecular architectures dramatically influences its catalytic behaviour. Mechanically interlocked molecules consist of two components, which are inseparable from each other, but not directly connected e.g. akin to links in a chain. Components bound in this manner are said to be linked by a mechanical bond. The forced proximity of interlocked components allows for powerful interactions between them which are not observed in non-interlocked structures. Furthermore, the unique three-dimensional spatial arrangement of the components of the interlocked structure can be designed to form a host cavity into which a monomer unit binds, increasing its potential reactivity to polymerisation by placing it in a well-defined reactive environment. Such an interlocked catalyst mimics the spatially defined active sites of enzymes. Indeed, a range of interlocked structures have been shown to be catalytically active, displaying enhanced selectivity for various organic reactions compared to non-interlocked catalyst analogues. Despite this, with one exception, mechanical bonding has not been exploited for polymerisation catalysis.This project seeks to build upon on those preliminary results, exploring the relationship between the structure of mechanically interlocked catalysts and polymer properties in order to develop a family of such catalysts for the formation of sustainable polymers. Many conventional catalysts feature multiple catalytic components, typically either by binding two metal atoms in a rigid framework, or through the addition of a second co-catalyst to the mixture. This project will seek to demonstrate an unprecedented strategy of developing mechanically bound catalysts where all requisite components are incorporated in a single molecule. This unique approach uses the spatial constraints of interlocked systems to hold the components of the catalyst in close proximity, without using the rigid frameworks often found in two-centred catalysts. In addition, control over the relative proximity of the interlocked components may enable catalysis to be switched on-and-off selectively or for the reactivity of the catalyst to be modified on-demand, for instance by shielding and exposing different reactive sites on a catalyst framework. Switchability will allow for 'designer polymers', facilitating exquisite control over polymer constitution and properties to produce highly desirable polymeric materials derived from renewable and biodegradable monomer sources. This project falls within the EPSRC Manufacturing the Future, Catalysis and Synthetic Supramolecular Chemistry research areas.

聚合物由长链组成，由许多重复的较小分子（称为单体）组成。在现代生活中，聚合物材料具有广泛的应用，例如服装，电子和药物，因为可以通过仔细的单体选择来设计其所需的物理和化学特性。但是，许多聚合物材料是由不可再生的单体产生的，并且是不可生物降解的，这引起了对其未来的制造和处置的严重关注。因此，在开发更环保的可持续途径上以生物降解的聚合物开发更多的公众和学术兴趣。聚合物的生产需要催化剂，最常见的是含有金属，以影响单体单元的管制连接以形成聚合物链。催化剂中金属的环境由周围原子的排列决定，在指定催化剂性能和选择性方面起着关键作用。这种控制对于形成具有明确特性的材料，例如强度和温度抗性，对于任何给定的应用至关重要。机械互锁的分子由两个分量组成，它们彼此密不可分，但不直接连接，例如类似于链条中的链接。据说以这种方式结合的组件与机械键相连。互锁组件的强制接近允许它们之间的强大相互作用，而它们在非锁定结构中未观察到。此外，可以设计互锁结构组件的独特三维空间排列，以形成宿主腔，单体单元结合到其中，从而通过将其放置在定义明确的反应环境中来增加其对聚合的潜在反应性。这种互锁的催化剂模仿了酶的空间定义的活性位点。实际上，与非锁定的催化剂类似物相比，一系列互锁的结构已显示为催化活性，对各种有机反应的选择性提高。尽管如此，除了一个例外，还没有利用机械键合进行聚合催化。该项目试图建立在这些初步结果的基础上，探索机械互锁的催化剂和聚合物特性之间的关系，以便开发这种催化剂的家族，以形成可持续聚合物的可持续聚合物。许多常规的催化剂具有多种催化成分，通常通过在刚性框架中结合两个金属原子，或通过将第二个共催化剂添加到混合物中。该项目将寻求展示一种前所未有的策略，以开发机械结合的催化剂，其中所有必要的成分都纳入单个分子中。这种独特的方法使用互锁系统的空间约束将催化剂的组件保持在近距离状态，而无需使用经常在两个中心的催化剂中发现的刚性框架。此外，控制互锁组件的相对接近性可以使催化有选择地打开催化，也可以使催化剂的反应性进行按需修改，例如，通过屏蔽和揭示催化剂框架上的不同反应位点。切换性将允许“设计器聚合物”，从而促进对聚合物构成和特性的精美控制，从而产生源自可再生和可生物降解的单体源的高度理想的聚合物材料。该项目属于EPSRC制造的未来，催化和合成超分子化学研究领域。