Investigating new porous organic materials and their application in porous liquids

多孔材料的研究领域正在迅速扩大，对金属有机框架（MOFs）和共价有机框架（COFs）等既定类别的持续兴趣，以及对多孔有机笼（POC）和多孔液体的日益关注。这包括气体储存和分离，因为它们的特定孔径允许捕获气体，或阻止较大的气体分子通过，充当分子筛。2研究也进入催化，因为这些材料可以产生非常大的表面积与体积比，允许催化位点的高度分散，并且还可以提供空间上定制的活性位点，其可以允许对映体选择性反应。3然而，较大的骨架如MOFs和COFs具有它们的缺点，包括不能溶解在有机溶剂中。多孔有机笼是一类相对较新的多孔材料，并且与扩展框架不同，它由含有永久空腔的离散分子单元组成，该空腔可以在固态下组装以形成互连的孔网络。笼的离散性意味着它们是溶液可加工的，并且使它们更容易溶解在有机溶剂中。一类新型多孔材料的概念，称为“多孔液体”，由James于2007年提出，并将这些材料描述为具有永久固有孔隙率的液体。4提出了三种不同类型的多孔液体：类型1 -由具有内部空腔的分子组成的纯液体，以及防止多孔性坍塌和损失的刚性;类型2 -溶解在空间位阻溶剂中的空宿主（同样，需要刚性离散分子来防止孔的塌陷，例如POC的塌陷）;和类型3 -分散在溶液中的固体微孔框架以产生流体多孔材料。在所有情况下，要考虑的主要因素之一是结构，以及它们是否会与分子间孔相互作用。这方面的一个例子包括使用长链烷烃，其可以穿过相邻分子的“窗口”并占据空腔，导致孔隙率的净损失。该项目旨在探索新的多孔有机笼和多孔液体的合成，建立在库珀等人的工作基础上。他在2015年报道了第一种2型多孔液体。5为了生产这些2型多孔液体，研究了溶解在各种大体积溶剂中的高可溶性多孔有机笼的使用。该项目还旨在改进气体吸附，因为与固态相比，许多当前系统作为多孔液体失去了孔隙度。该项目还旨在探索开发分子笼的可能性，这些分子笼能够在外部刺激（如热或光）下发生变化，以及如何将其应用于多孔液体。A.王文，微孔结构固体，皇家化学学会，2007。北川河Kitaura和S.诺萝安琪化学国际版，2004，43，2334-2375.J. Cejka，G. Centi，J，Perez-Pariente，and W. J.Roth，Catal. Today.，2012，179，2- 15. N. O'Reilly，N. Giri和S. L. James，Chem. Eur. J.，13，2007，3020- 3025. Giri，M. G.德尔波波洛湾梅洛河L. Greenaway，K. Rätzke，T.科申湖Pison，M. F. Costa Gomes，A. I.库珀和S. L. James，Nature，527，2015，216-220.

The field of porous materials research is rapidly expanding, with continuing interest in established classes such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), sitting alongside increasing focus on porous organic cages (POCs) and porous liquids.1 These materials are currently in the limelight due to their wide array of applications. This includes gas storage and separation due to their specific pore size allowing entrapment of gases, or the prevention of larger gas molecules to pass through, acting as a molecular sieve.2 Research has also moved into catalysis, as these materials can produce very large surface area to volume ratios, allowing for a high dispersion of catalytic sites, and can also provide a sterically-tailored active site which can allow for enantioselective reactions.3 However, larger frameworks such as MOFs and COFs have their drawbacks, including the inability to be dissolved in organic solvents. Porous organic cages are a relatively new class of porous material, and, unlike extended frameworks, are comprised of discrete molecular units containing a permanent cavity that can assemble in the solid state to form interconnected pore networks. The discrete nature of the cages means they are solution processable and makes them significantly easier to dissolve in organic solvents.The concept of a novel class of porous material, referred to as 'porous liquids', was proposed by James in 2007, and described these materials as liquids with permanent intrinsic porosity.4 Three different types of porous liquids were proposed: Type 1 - neat liquids consisting of molecules with an internal cavity, and rigidity to prevent the collapse and loss of porosity; Type 2 - empty hosts dissolved in a sterically hindered solvent (again, rigid discrete molecules are required to prevent the collapse of the pore, such as that of POCs); and Type 3 - solid microporous frameworks dispersed within a solution to produce a fluid porous material. In all cases, one of the major factors to consider is the structure, and whether they will interact with an intermolecular pore. An example of this includes using long chain alkanes which can pass through the 'window' of a neighbouring molecule and occupy the empty cavity, resulting in the net loss of porosity. This project aims to explore the synthesis of new porous organic cages and porous liquids, building on the work by Cooper et al. who reported the first Type 2 porous liquids in 2015.5 To produce these type 2 porous liquids, the use of highly soluble porous organic cages dissolved in a variety of bulky solvents were investigated. This project also aims to make improvements to gas sorption, as many of the current systems lose porosity as a porous liquid compared to those in the solid-state. This project also aims to explore the possibility of developing molecular cages that have the ability to change under external stimuli such as heat or light, and how this can then be applied to porous liquids.ReferencesP. A. Wright, Microporous Framework Solids, Royal Society of Chemistry, 2007.S. Kitagawa, R. Kitaura, and S. Noro, Angew. Chem. Int. Ed., 2004, 43, 2334-2375.J. Cejka, G. Centi, J, Perez-Pariente, and W. J.Roth, Catal. Today., 2012, 179, 2-15.N. O'Reilly, N. Giri, and S. L. James, Chem. Eur. J., 13, 2007, 3020-3025.N. Giri, M. G. Del Pópolo, G. Melaugh, R. L. Greenaway, K. Rätzke, T. Koschine, L. Pison, M. F. Costa Gomes, A. I. Cooper and S. L. James, Nature, 527, 2015, 216-220.