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.

聚合物是由许多重复的小分子组成的长链，称为单体。聚合物材料在现代生活中是必不可少的，它在服装、电子和医药等领域有着广泛的应用，因为它们所需的物理和化学性能可以通过仔细的单体选择来设计。然而，许多聚合物材料是由不可再生的单体生产的，并且是不可生物降解的，这对其未来的生产和处置提出了严重的环境问题。因此，越来越多的公众和学术界对开发更环保的可持续途径来生产生物可降解聚合物感兴趣。聚合物生产需要催化剂，通常含有金属，以影响单体单元的调节连接，形成聚合物链。金属在催化剂中的环境，由其周围原子的排列决定，在指定催化剂的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性能的材料至关重要，例如强度和耐温性，对于任何给定应用都至关重要。最近的研究表明，将金属结合到复杂的分子结构中会极大地影响其催化行为。机械互锁的分子由两种成分组成，这两种成分彼此不可分离，但不直接连接，例如类似于链中的链接。以这种方式结合的部件称为用机械键连接。互锁组件的强制接近允许它们之间强大的相互作用，这在非互锁结构中是观察不到的。此外，联锁结构组件的独特三维空间排列可以设计成形成一个宿主腔，使单体单元结合，通过将其放置在一个明确定义的反应环境中，增加其对聚合的潜在反应性。这种联锁催化剂模拟了酶在空间上的活性位点。事实上，一系列联锁结构已被证明具有催化活性，与非联锁的催化剂类似物相比，对各种有机反应表现出更高的选择性。尽管如此，除了一个例外，机械键还没有被用于聚合催化。该项目旨在以这些初步结果为基础，探索机械联锁催化剂结构与聚合物性能之间的关系，以开发一系列此类催化剂，用于形成可持续聚合物。许多传统催化剂具有多种催化成分，通常是通过将两个金属原子结合在一个刚性框架中，或者通过在混合物中添加第二种助催化剂。该项目将寻求展示一种前所未有的开发机械结合催化剂的策略，其中所有必需的成分都包含在单个分子中。这种独特的方法利用了联锁系统的空间约束，使催化剂的组分保持在很近的距离，而不使用双中心催化剂中常见的刚性框架。此外，通过控制联锁组分的相对接近度，可以选择性地开启和关闭催化剂，或者根据需要修改催化剂的反应性，例如通过屏蔽和暴露催化剂框架上的不同反应位点。可切换性将允许“设计聚合物”，促进对聚合物结构和性能的精细控制，以生产源自可再生和可生物降解单体来源的高度理想的聚合物材料。该项目属于EPSRC制造未来，催化和合成超分子化学研究领域。