Polyoxometalate-Based Ionic Frameworks for Highly Selective CO ₂ Capture and Separation

Abstract

During utilizing structural and functional advantages of polyoxometalates (POMs) for enhanced applications, the suitable assembly of these clusters in framework materials acting as the binding nodes represents one of the mostly favourable approaches. In contrast to well-developed coordination/covalent combinations, a convenient strategy to build the porous structures of POMs with smaller sized counterions as bridging ligand via ionic interaction is developed here to reinforce the capability in gas adsorption in parallel to MOFs/COFs. With this goal, a series of POMs-based ionic

Chiral hexamers of organically modified polyoxometalatesviaionic complexation

“…The status of the hexamer is identical to one linking node in the reported pattern. 20,25 But, instead of framework interlinkages, a solitary hexamer structure emerges here, owing to the steric hindrance effect of anthracene. Importantly, the other twelve sodium ions locate around the hexamer, guiding the formation of chirality.…”

“…This facilitates the further self-assembly. According to the results reported in the literature, 20,25 the terminal oxygens of POMs can usually be combined with Na + . Thus, the sodium perchlorate (the concentration of NaClO 4 is 4 mM) was selected and added to this solvent as the Na + source to support its assembly.…”

“…The result demonstrates that this position must be occupied by a suitable small molecule or ion since it was found to be held by either water or ammonium ions in the framework structure. 20,25 Six AS-MnMo 6 anions assemble into hexamers in a fashion of octahedral structure via the linkage of four sodium cations in tetrahedral form through ionic interaction of [MovO⋯Na]. Four terminal oxygens of one AS-MnMo 6 are combined with two sodium ions with a distance of 2.4 Å, and four sodium cations interact with three AS-MnMo 6 anions (Fig.…”

“…23,24 Recently, ionic frameworks of these modified clusters have been prepared successfully. 20,25 But more than that, the framework comprising of a symmetric oligomer only form racemic chiral hexamer nodes where two types of enantiomers are alternately arrayed to form achiral assemblies (Fig. 1a).…”

The inorganic cation-tailored “trapdoor” effect of silicoaluminophosphate zeolite for highly selective CO2 separation

“… 4 Over recent years, a variety of solid porous materials have been investigated for the separation of CO 2 /CH 4 and CO 2 /N 2 , 2 a , c ,3 b ,5 including carbon-based materials, 6 zeolites, 7 metal–organic frameworks (MOFs), 8 N or amine-functionalized solid porous materials, 9 porous organic solids, etc. 10 Taking into account the key factors governing the separation efficiency of CO 2 such as adsorption capacity, selectivity, adsorption/desorption kinetics, and cost, zeolites, in particular, the small-pore zeolites with the “trapdoor” effect, have more advantages over other materials for industrial utilization. 4 a , b…”