Flexibility in metal–organic frameworks : a basic understanding

Much has been written about the fundamental aspects of the metal-organic frameworks (MOFs). Still, details concerning the MOFs with structural flexibility are not comprehensively understood. However, a dramatic increase in research activities concerning rigid MOFs over the years has brought deeper levels of understanding for their properties and applications. Nonetheless, robustness and flexibility of such smart frameworks are intriguing for different research areas such as catalysis, adsorption, etc. This manuscript overviews the different aspects of framework flexibility. The review has touched lightly on several ideas and proposals, which have been demonstrated within the selected examples to provide a logical basis to obtain a fundamental understanding of their synthesis and behavior to external stimuli

Latent olefin metathesis catalysts

Olefin metathesis is a versatile synthetic tool for the redistribution of alkylidene fragments at carbon-carbon double bonds. This field, and more specifically the development of task-specific, latent catalysts, attracts emerging industrial and academic interest. This tutorial review aims to provide the reader with a concise overview of early breakthroughs and recent key developments in the endeavor to develop latent olefin metathesis catalysts, and to illustrate their use by prominent examples from the literature

Macrocyclic cyanocobalamin (vitamin B12) as a homogeneous electrocatalyst for water oxidation under neutral conditions

Highly water-soluble cyanocobalamin (also known as vitamin B-12) is the most structurally macrocyclic complex comprising cobalt in the center of a corrin ring. Interestingly, it acts as a robust electrocatalyst in water oxidation at similar to 0.58 V overpotential with a faradaic efficiency of 97.50% under neutral buffered conditions. The catalyst is impressively stable even after long-term bulk electrolysis, and homogeneous in nature, as established by a series of experiments and characterization techniques

Metal-organic frameworks applied for water purification

Metal-organic frameworks (MOFs) which are materials constructed from metal ions/clusters bridged with organic linkers have emerged as an important family of porous materials for widely varying applications. The purification of water polluted with both of organic and inorganic contaminants is a potentially promising application of MOFs since the chemical and thermal properties of the porous materials are easily tunable, e.g. ligand modification, different metal, etc. The demonstration of alignment and theobtained insights facilitate the direction of designing ideal MOF materials with improved water stability for application in water purification. This review gives a brief overview and will be beneficial to the design, functionalization, and promotion of the development of MOFs as adsorbent materials for applications in water purification

Metal-organic frameworks applied for water purification

Metal-organic frameworks (MOFs) which are materials constructed from metal ions/clusters bridged with organic linkers have emerged as an important family of porous materials for widely varying applications. The purification of water polluted with both of organic and inorganic contaminants is a potentially promising application of MOFs since the chemical and thermal properties of the porous materials are easily tunable, e.g. ligand modification, different metal, etc. The demonstration of alignment and theobtained insights facilitate the direction of designing ideal MOF materials with improved water stability for application in water purification. This review gives a brief overview and will be beneficial to the design, functionalization, and promotion of the development of MOFs as adsorbent materials for applications in water purification

Selective cyclodimerization of epichlorohydrin to dioxane derivatives over MOFs

Glycerol can be converted to valuable products such as epichlorohydrin which is an important intermediate applied in various industries. For example, dioxane derivatives, which are important pharmaceuticals, can be obtained from epichlorohydrin. In the present study, ZIF-8, ZIF-67, MIL-100, and UiO-66 were applied for the direct cyclodimerization of epichlorohydrin. These MOFs were selected because they were already applied as active catalysts in ring opening of epoxides. Among them, ZIF-8 showed the highest activity and selectivity in the absence of any solvent or co-catalyst. Using ZIF-8 as a catalyst, the cyclodimer product (1,4-dioxane 2,5-bis-chloromethyl) was obtained in a yield of about 70% which was significantly superior to previous homo or heterogeneous catalysts for this reaction. Due to ZIF-8 structure and the proposed mechanism, the cyclodimerization reaction catalyzed either by the defects in the structure and/or on the surface. Furthermore, acidic-basic characteristics were also in play. The NH3 and CO2 temperature-programed desorption technique were utilized to identify the active sites and thereby reaction mechanism. Moreover, because of similar properties of ZIF-8 to zeolites, the activity of commercial ZSM-5 for the same reaction was also investigated in this work