Designing Chemistry and Morphology in Metal-Organic Framework Gels, Liquids and Glasses

金属有机骨架(MOF)是由无机节点通过有机连接物连接而成的三维结构。不同的元素或功能可以很容易地整合到过多的纳米结构中，导致了大量化合物的出现。已有超过60,000个晶体结构被报道，这些晶体结构可以被‘调整’以显示出对预定目标客体分子的特殊选择性。来自西北大学和贝尔法斯特女王大学的两款产品已经商业化，涉及有毒气体储存和水果包装领域。此外，已提出将其用于高度选择性的二氧化碳捕获、药物输送、化学传感、有毒气体分离和有害废物储存应用，这将带来巨大的社会和经济效益，但尚未实现。这在一定程度上是由于化学合成取得的重大进展与对其物理性质研究的匮乏之间的差距。因此，令人非常惊讶的是，即使是所有物理性质中最基本的物质状态，也是MOF领域研究最少的领域之一。因此，这项建议旨在解决这种偏向有序的结晶固体结构域的问题，考虑到对该领域的研究投入，以及将非晶态结构域的机械稳定性与MOF提供的化学机会相结合的潜在好处，这是至关重要的。最近发现的MOF家族的玻璃形成能力提供了一种诱人的前景，即通过在随后的熔化和液态淬火之前首先调整母晶体框架的化学性质来精确设计功能玻璃。以这种方式将功能从晶体转移到玻璃将使下一代功能玻璃得以生产。这种材料将处于将MOF从目前对结晶多孔态的关注转移到最前沿的努力的前沿。在该项目过程中将生产两类新的功能MOF玻璃：(I)用于分离的多孔MOF玻璃和(Ii)用于高级光学应用的手性MOF玻璃。对于前者，鉴于目前混合基质膜存在化学兼容性问题和活性成分的减少，开发用于气体分离的多孔MOF-玻璃或MOF-玻璃复合膜将被证明是该领域的重大进步。此外，还将研究MOF在液相中的反应，并研究所生成的多元玻璃的结构和性能。MOF的“软”性质也会导致一些结构在后处理过程(如烧结、球磨、造粒)中的结构崩溃，用于将纳米晶粉末转化为工业上可用的形貌。因此，从微晶粉末中开发各种形貌(即薄膜、微珠和自支撑、无粘结剂的膜)对于该领域的应用是绝对必要的。该项目致力于从根本上扩大我们对该领域的基本理解，同时弥合基础科学和工业相关性之间的差距，该项目具有高度跨学科的性质。因此，这项建议的主要目标是：(1)创造新的多孔手性MOF玻璃；(2)通过将晶态MOF和它们的玻璃相对应物结合起来，创造用于分离的新复合材料；(3)制作两种MOF液体反应的二元相图，并分析形成的产物；(4)使不稳定的MOF球交联化，并将该方法推广到另一个MOF家族。

Metal-organic frameworks (MOFs) are three-dimensional structures composed of inorganic nodes, connected by organic linkers. The ease at which different elements or functionalities can be incorporated into a plethora of nanoscopic architectures has led to the population of an enormous class of compounds. Over 60,000 crystalline structures have been reported, which can be 'tuned' to exhibit exceptional selectivity for pre-determined target guest molecules. Two products, from companies span out of Northwestern and Queen's University Belfast, have been commercialised, in the areas of toxic gas storage and fruit packaging. Furthermore, huge societal and economic benefits from their use in highly selective CO2 capture, drug delivery, chemical sensing, toxic gas separations and harmful waste storage applications have been proposed, though not delivered. This is partly due to the gap between the significant strides made in chemical synthesis, and a dearth of work on their physical properties.It is therefore highly surprising that even the most basic of all physical properties, the state of matter, represents one of the most under-researched areas in the MOF field. This proposal hence aims at addressing this bias towards the ordered, crystalline solid domain, which is vital given the research invested into the field and the potential benefits from the combination of the mechanical stability of the amorphous domain, with the chemical opportunities afforded by MOFs.The recent discovery of the glass-forming ability of the MOF family offers the tantalising prospect of accurately designing functional glasses by first tuning the chemical properties of the parent crystalline framework, prior to subsequent melting and liquid quenching. The transfer of functionality from crystal to glass in this manner will enable the next generation of a plethora of functional glasses to be produced. Such materials will lie at the forefront of efforts to move MOFs away from the current focus on the crystalline porous state. Two new classes of functional MOF-glasses will be produced in the course of the project; (i) porous MOF-glasses for separations and (ii) chiral MOF glasses for advanced optical applications. With respect to the former, the development of porous MOF-glasses or MOF-glass composite membranes for gas separations would prove a significant advancement in the field, given the current mixed matrix membranes suffer from chemical compatibility problems and a reduction in active component. In addition, reactions between MOFs in the liquid phase will be studied, and the structure and properties of the resultant multicomponent glasses produced investigated.The 'soft' nature of MOFs also leads to the structural collapse of some frameworks during the post-processing processes (e.g. sintering, ball-milling, pelletisation) used to convert nano-crystalline powders to industrially useable morphologies. The development of a variety of morphologies (i.e. thin films, beads, and self-supporting, binder-free membranes from microcrystalline powders is therefore absolutely essential for the field to move forwards to application. Concentrating on both fundamentally expanding our basic understanding of the field and at the same time bridging the gap between basic science and industrial relevance, this project is highly interdisciplinary in nature. The overarching aims of this proposal are thus to; (i) create new porous and chiral MOF-glasses (ii) create new composite materials for separation by combining crystalline MOFs and their glassy counterparts, (iii) produce a binary phase diagram for the reaction of two MOF liquids and analyse the products formed and (iv) cross-link unstable MOF spheres produced in previous work by the group, and extend the methodology to another MOF family.