Porous Liquids for Catalysis

多孔液体（PLs）是一种令人兴奋的新型反直觉多孔材料，它结合了微孔固体的特性和液体的流动性。像它们的固体对应物一样，这些有孔的液体具有气体吸收和释放以及客体选择性的能力。然而，与固体多孔材料不同的是，它们也有潜在的独特应用，例如能够在连续系统周围泵送，从而促进客加载/卸载步骤，或者用作气体负载的反应溶剂。尽管有这种潜力，PLs在除气体吸收和选择性以外的领域的应用尚未研究。最近，我们报道了使用多孔有机笼（POCs）（包含永久分子腔的离散分子，可通过窗户进入）形成高空腔浓度的PLs，并证明了它们比纯液体更能增加对一系列气体（如CO2， CH4, Xe, SF6）的吸收(Nature, 2015, 527,216; Chem。科学。化工学报，2017,8,2640,ChemRxiv, 2021, DOI:10.26434/ ChemRxiv .14719503.v2)。此外，也有报道使用笼型溶液催化二氧化碳转化为环状碳酸盐（可持续能源燃料，2019,3,2567），并作为纳米反应器(化学。Soc。Rev., 2008, 37, 247)。这些系统不同于PLs，后者被定义为具有永久的空孔，可被客体进入，因为客体与占据空腔的溶剂竞争，或者客体结合受到疏水效应的驱动。在本项目中，我们将以这些初步报告为基础，探索将PLs应用于催化领域的不同方法。这包括在化学计量气体反应中使用负载气体的PLs作为可重复使用和可控的外部气源，作为通过“模拟”通常只能在高压下实现的高浓度气体来进行低压气体反应的溶剂，以及作为纳米反应器通过限制催化小分子反应。一旦我们对这些不同的方法有了透彻的了解，我们将寻求将其转化为高通量工作流程，目的是能够使用PLs快速筛选一系列涉及气体作为试剂掺入的催化反应。

Porous liquids (PLs) are an exciting new class of counterintuitive porous materials that combine the properties of a microporous solid with the mobility of a liquid. Like their solid counterparts, these liquids with holes have the capability to demonstrate gas uptake and release, and guest selectivity. However, unlike solid porous materials, they could also potentially have unique applications, such as the ability to be pumped around a continuous system facilitating guest loading/unloading steps, or being used as a gas-loaded reaction solvent. Despite this potential, the application of PLs in areas other than gas uptake and selectivity has not been investigated. Recently, we reported the formation of high cavity concentration PLs using porous organic cages (POCs) - discrete molecules containing permanent molecular cavities accessible through windows - and demonstrated their ability to exhibit increased uptake of a range of gases (e.g., CO2, CH4, Xe, SF6) over neat liquids (Nature, 2015, 527, 216; Chem. Sci., 2017, 8, 2640, ChemRxiv, 2021, DOI:10.26434/chemrxiv.14719503.v2). In addition, there have been reports of the use of solutions of cages for catalytic CO2 conversion into cyclic carbonates (Sustainable Energy Fuels, 2019, 3, 2567), and as nanoreactors (Chem. Soc. Rev., 2008, 37, 247). These systems differ from PLs, which are defined as having permanently empty pores that are accessible to guests, due to either guests being in competition with the solvent which occupies the cavities or guest binding being driven by a hydrophobic effect. In this project, we will build on these initial reports and explore different ways of applying PLs in the area of catalysis. This includes the use of gas-loaded PLs as a reusable and controllable external gas source in stoichiometric gas reactions, and as a solvent to carry out lower pressure gas reactions by 'simulating' high gas concentrations that are normally only achieved at higher pressures, and as nanoreactors to catalyse small molecule reactions by confinement. Once we have a thorough understanding of these different methodologies, we will then seek to translate this into a high-throughput workflow with the aim of being able to use PLs to rapidly screen a range of catalytic reactions involving the incorporation of a gas as a reagent.