Metal organic frameworks (MOFs) are considered as a group of compounds, either metal ions or clusters, harmonized with organic ligands to form one or some dimensional structures. In addition to resilient bonds between inorganic and organic units, reticular synthesis creates MOFs, accurate selection of constituents of which can produce high thermal and chemical stability and crystals of ultrahigh porosity. Other solids have not shown the same accuracy normally used in chemical modification and even the capability of increasing their metrics with no modification of the underlying topology. With shape of building units and chemical compositions multiplying based on specific structures, MOFs might result in compounds that propose a synergistic mixture of features. This study presents up to date advances in both synthesis methods of MOFs and structural characteristics. Furthermore, the use of MOFs in different fields such as the removal of absorption and separation of toxic substances from gas and liquid, catalysts, a variety of sensors, storage of clean energies and environmental applications, medical and biological applications, and optoelectronic equipment is included.

A review on metal-organic frameworks: Synthesis and applications

Metal–organic frameworks (MOFs) are highly versatile materials that find applications in several fields. Highly stable zirconium/hafnium-based MOFs were recently introduced and nowadays represent a rapidly growing family. Their unique and intriguing properties make them privileged materials and outstanding candidates in heterogeneous catalysis, finding use either as catalysts or catalyst supports. Various techniques have been developed to incorporate active species into Zr-MOFs, giving rise to catalysts that often demonstrate higher performances or unusual activity when compared with their homogeneous analogues. Catalytic functions are commonly incorporated at the zirconium-oxide node, at the linker, or encapsulated in the pores. Representative examples are discussed, and advantages in adopting Zr- and Hf-MOFs in catalytic applications are highlighted.

Catalytic Zirconium/Hafnium-Based Metal–Organic Frameworks

The variety of functionalities and porous structures inherent to metal-organic frameworks (MOFs) together with the facile tunability of their properties makes these materials suitable for a wide range of existing and emerging applications. Many of these applications are based on processes involving interaction of MOFs with guest molecules. To optimize a certain process or successfully design a new one, a thorough knowledge is required about the physicochemical characteristics of materials and the mechanisms of their interaction with guest molecules. To obtain such important information, various complementary analytical techniques are applied, among which vibrational spectroscopy (IR and Raman) plays an important role and is indispensable in many cases. In this review, we critically examine the reported applications of IR and Raman spectroscopies as powerful tools for initial characterization of MOF materials and for studying processes of their interaction with various gases. Both the advantages and the limitations of the technique are considered, and the cases where IR or Raman spectroscopy is preferable are highlighted. Peculiarities of MOFs interaction with specific gases and some inconsistent band assignments are also emphasized. Summarizing the broad analytical possibilities of the IR and Raman spectroscopies, we conclude that it can be applied in combinations with other techniques to explicitly establish the structure, properties, and reactivity of MOFs.

Power of Infrared and Raman Spectroscopies to Characterize Metal-Organic Frameworks and Investigate Their Interaction with Guest Molecules

The development of porous nanomaterials with high efficiency for environmental remediation has been attracting significant attention and becoming an important topic recently. Metal–organic frameworks (MOF) are hybrid inorganic–organic porous materials containing a metal–oxygen cluster and organic molecules, which are becoming an alternative to traditional inorganic porous materials, such as zeolite and silica, for environmental remediation owing to their fascinating characteristics. Recent studies have demonstrated that MOF are one of the most efficient adsorbents or catalysts in gas separation, solar energy conversion and photocatalytic applications. This review mainly summarizes the recent progress on the adsorptive and degradation treatment of various gaseous pollutants by MOF materials. In this review, the physical and chemical adsorption of gaseous pollutants in air by MOFs will be discussed, and strategies for maximizing the adsorption capacity by tuning the physical and chemical properties of MOFs at the atomic level are systematically summarized. In particular, a promising strategy based on the synergistic effect of adsorption-concentrated photocatalytic oxidation of gaseous pollutants with this newly emerging MOF is also introduced, as it holds great potential in the treatment of gaseous pollutants in consideration of its high efficiency, low cost and being free from secondary pollution. In the end, the challenges faced, the prospects, and our personal perspective on future research directions are also estimated and elucidated.

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Metal–organic framework-based nanomaterials for adsorption and photocatalytic degradation of gaseous pollutants: recent progress and challenges

Metal–organic frameworks (MOFs) are hybrid solids formed of organic and inorganic building blocks. While the nature of electron addition, removal, and transport is well known in organic and inorganic crystals, the behaviour of hybrid materials is poorly understood in comparison. We review progress over the past 5 years in the study of electroactive MOFs with redox activity promoted by different strategies: (i) redox-active metals; (ii) redox-active organic linkers; (iii) host–guest interactions; and (iv) charge-transfer frameworks. The properties and performance of materials are analysed with respect to emerging application areas including electrochemical energy storage (batteries and supercapacitors) and photo-/electrochemical reactions (solar cells, fuels and electrocatalysis). We further highlight the development of mixed-valence MOFs, which have been found to give rise to unprecedented charge transport in semiconducting and metallic hybrid frameworks.

Redox-active metal–organic frameworks for energy conversion and storage

Facile loading of Cu(I) in MIL-100(Fe) through redox-active Fe(II) sites and remarkable propylene/propane separation performance

Adsorptive separation of xenon/krypton mixtures using a zirconium-based metal-organic framework with high hydrothermal and radioactive stabilities.

Creating high CO/CO2 selectivity and large CO working capacity through facile loading of Cu(I) species into an iron-based mesoporous metal-organic framework

Creation of mesoporous defects in a microporous metal-organic framework by an acetic acid-fragmented linker co-assembly and its remarkable effects on methane uptake

Ah Reum Kim

Papers

Facile loading of Cu(I) in MIL-100(Fe) through redox-active Fe(II) sites and remarkable propylene/propane separation performance

Adsorptive separation of xenon/krypton mixtures using a zirconium-based metal-organic framework with high hydrothermal and radioactive stabilities.

Creating high CO/CO2 selectivity and large CO working capacity through facile loading of Cu(I) species into an iron-based mesoporous metal-organic framework

Creation of mesoporous defects in a microporous metal-organic framework by an acetic acid-fragmented linker co-assembly and its remarkable effects on methane uptake

Highly selective adsorption of CO over CO2 in a Cu(I)-chelated porous organic polymer.