A Breathing Ionic Crystal Displaying Selective Binding of Small Alcohols and Nitriles: K3[Cr3O(OOCH)6(H2O)3][-SiW12O40]⋅16 H2O

Abstract

Molecular sieving to take your breath away: The breathing ionic crystal 1 is synthesized by the complexation of Keggin‐type [α‐SiW12O40]4− (red) polyoxometalate with a macro cation [Cr3O(OOCH)6(H2O)3]+ (green and white). The water of crystallization is easily removed from 1 by evacuation to form a guest‐free phase 2. Compound 2 reversibly adsorbs small alcohols and nitriles as well as water, while longer‐chain alcohols and nitriles were excluded, which shows the novel molecular sieving of small hydrophilic molecules by 2.

Structure of copper and nickel amine complexes with polyoxometallates and their adsorption properties relative to lower alcohols

“…Such behavior has been previously observed for other materials consisting of complex cations and POM anions [5][6][7][8][9][10]. The X-ray diffraction structural analysis data suggest that such behavior should be attributed to the ionic structure of the adsorbents, i.e., the lack of a coordination interaction between the metal ion of the cationic species and the POM oxygen atoms.…”

“…Such variation leads to different stoichiometry of the compounds and, thereby, to different types of ion packing in the crystal lattice, leading to different porosity of the adsorbents (from the viewpoint of the dimensions and nature of the channel walls) [5][6][7][8][9][10].…”

“…However, this aspect of the chemistry of these compounds has not been studied extensively. Recent studies have shown that ionic compounds derived from chromium(III) or palladium(II) cation metal complexes and Keggin anions [XW 12 O 40 ] n-have a series of promising properties differentiating them from other adsorbents [5][6][7][8][9][10].In our previous work [11,12], we showed that the products of the reaction of copper(II) and nickel(II) amine complex perchlorate salts with various polyoxometallate anions (POM) in aqueous ethanol solution are crystalline materials, which, after drying in a desiccator over P 2 O 5 , contain stoichiometric amounts of solvent molecules of crystallization, mainly, water. The samples obtained may be dehydrated by heating.…”

“…However, this aspect of the chemistry of these compounds has not been studied extensively. Recent studies have shown that ionic compounds derived from chromium(III) or palladium(II) cation metal complexes and Keggin anions [XW 12 O 40 ] n-have a series of promising properties differentiating them from other adsorbents [5][6][7][8][9][10].…”

Transformation of a Chiral Nanoporous Bimetallic Cyano-Bridged Framework Triggered by Dehydration/Rehydration

“…[24][25][26][27][28] Some porous metalsorganic polymers have been reported to have significant cell volume changes upon guest exchange. 27,[29][30][31] Dynamic structural transformation, based on flexible porous frameworks, is one of the most interesting phenomena in coordination polymers. Recently a number of studies on such dynamic porous coordination networks have appeared.…”