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

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.

ROD-8, a rod MOF with a pyrene-cored tetracarboxylate linker: framework disorder, derived nets and selective gas adsorption

Reported here is a new Cd^II-based metal–organic framework (MOF), ROD-8, based on the rod secondary building unit (SBU) and tetratopic linker 1,3,6,8-tetrakis(p-benzoic acid)pyrene.

Luminescent metal–organic frameworks for chemical sensing and explosive detection

This review provides an update on the photoluminescence properties of LMOFs and their utility in chemical sensing and explosive detection.

Single-crystal X-ray diffraction studies on structural transformations of porous coordination polymers

This review gives a brief overview of single-crystal X-ray diffraction studies and single-crystal to single-crystal transformations of porous coordination polymers.

A highly stable MOF with a rod SBU and a tetracarboxylate linker: unusual topology and CO2adsorption behaviour under ambient conditions

A Mn-based rod metal–organic framework (MOF), ROD-6, with a new lrk net is synthesized and studied with Ideal Adsorbed Solution Theory (IAST) for selective gas adsorption.