A Review on Breathing Behaviors of Metal-Organic-Frameworks (MOFs) for Gas Adsorption

Abstract

Metal-organic frameworks (MOFs) are a new class of microporous materials that possess framework flexibility, large surface areas, “tailor-made” framework functionalities, and tunable pore sizes. These features empower MOFs superior performances and broader application spectra than those of zeolites and phosphine-based molecular sieves. In parallel with designing new structures and new chemistry of MOFs, the observation of unique breathing behaviors upon adsorption of gases or solvents stimulates their potential applications as host materials in gas storage for renewable energy. This has attracted intense research energy to understand the causes at the atomic level, using in situ X-ray diffraction, calorimetry, Fourier transform infrared spectroscopy, and molecular dynamics simulations. This article is developed in the following order: first to introduce the definition of MOFs and the observation of their framework flexibility. Second, synthesis routes of MOFs are summarized with the emphasis on the hydrothermal synthesis, owing to the environmental-benign and economically availability of water. Third, MOFs exhibiting breathing behaviors are summarized, followed by rationales from thermodynamic viewpoint. Subsequently, effects of various functionalities on breathing behaviors are appraised, including using post-synthetic modification routes. Finally, possible framework spatial requirements of MOFs for yielding breathing behaviors are highlighted as the design strategies for new syntheses.

Effect of the structural constituents of metal organic frameworks on carbon dioxide capture

“…guest molecules, and can also possess flexible counterparts [117][118][119][120]. The MIL-53 series of MOFs are widely known examples of MOFs with breathing frameworks [48,121,122].…”

EPR Insights into Switchable and Rigid Derivatives of the Metal–Organic Framework DUT-8(Ni) by NO Adsorption

“…1 Reversible framework flexibility or switching as an answer to external stimuli like pressure, irradiation or adsorption of guest molecules is a unique feature of the 3 rd generation of MOFs. [2][3][4][5] In turns, these materials could be divided on several sub-classes depending on the stimuli-responsible structural transitions like "breathing" MOFs 2 or "gate pressure" MOFs. 3,6 The latter type of switchable MOF materials is of special interest for applications like gas separation 7 or sensors 8 due to the distinct separation of "non-porous" or "close pore" and "porous" or "open pore" states.…”

DFT-Derived Force Fields for Modeling Hydrocarbon Adsorption in MIL-47(V)

“…The predicted olefin/ paraffin selectivity decreases from ∼2.3 for C 3 to 1.7 for C 7 hydrocarbons under saturation conditions. 81 and Schneemann et al 87 Even though a variety of techniques have been explored for modeling these materials, 87 our focus here is limited to studying the adsorption of short linear alkanes in MIL-53(Cr) and MIL-53(Fe) using the VDW-DF2 FF.…”