Krause Simon, Evans Jack D, Bon Volodymyr, Senkovska Irena, Coudert François-Xavier, Maurin Gulliaume, Brunner Eike, Llewellyn Philip L, Kaskel Stefan
Nanochemistry Department, Max-Planck-Institute for Solid State Research, 70569 Stuttgart, Germany.
School of Physics, Chemistry and Earth Sciences, The University of Adelaide, South Australia 5000, Australia.
Chem Soc Rev. 2025 Feb 3;54(3):1251-1267. doi: 10.1039/d4cs00555d.
Nanoporous solids offer a wide range of functionalities for industrial, environmental, and energy applications. However, only a limited number of porous materials are responsive, the nanopore dynamically alters its size and shape in response to external stimuli such as temperature, pressure, light or the presence of specific molecular stimuli adsorbed inside the voids deforming the framework. Adsorption-induced structural deformation of porous solids can result in unique counterintuitive phenomena. Negative gas adsorption (NGA) is such a phenomenon which describes the spontaneous release of gas from an "overloaded" nanoporous solid adsorption-induced structural contraction leading to total pressure amplification (PA) in a closed system. Such pressure amplifying materials may open new avenues for pneumatic system engineering, robotics, damping, or micromechanical actuators. In this review we illustrate the discovery of NGA in DUT-49, a mesoporous metal-organic framework (MOF), and the subsequent examination of conditions for its observation leading to a rationalization of the phenomenon. We outline the development of decisive experimental and theoretical methods required to establish the mechanism of NGA and derive key criteria for observing NGA in other porous solids. We demonstrate the application of these design principles in a series of DUT-49-related model compounds of which several also exhibit NGA. Furthermore, we provide an outlook towards applying NGA as a pressure amplification material and discuss possibilities to discover novel NGA materials and other counterintuitive adsorption phenomena in porous solids in the future.
纳米多孔固体为工业、环境和能源应用提供了广泛的功能。然而，只有有限数量的多孔材料具有响应性，即纳米孔会根据外部刺激（如温度、压力、光或吸附在孔隙内使骨架变形的特定分子刺激的存在）动态改变其尺寸和形状。多孔固体的吸附诱导结构变形会导致独特的违反直觉的现象。负气体吸附（NGA）就是这样一种现象，它描述了气体从“过载”的纳米多孔固体中自发释放，吸附诱导的结构收缩导致封闭系统中的总压力放大（PA）。这种压力放大材料可能为气动系统工程、机器人技术、阻尼或微机械致动器开辟新途径。在这篇综述中，我们阐述了在介孔金属有机框架（MOF）DUT-49中发现NGA的过程，以及随后对其观察条件的研究，从而使该现象得到合理的解释。我们概述了确定NGA机理所需的决定性实验和理论方法的发展，并推导了在其他多孔固体中观察NGA的关键标准。我们展示了这些设计原则在一系列与DUT-49相关的模型化合物中的应用，其中几种化合物也表现出NGA。此外，我们展望了将NGA用作压力放大材料的应用前景，并讨论了未来发现新型NGA材料和多孔固体中其他违反直觉的吸附现象可能性。
