Concerted Functions of Anions and Cations in a Molecular Ionic Crystal with Stable Three-Dimensional Micropores

Abstract

The molecular ionic crystal [Cr3O(OOCCH═CH2)6(H2O)3]3[α-PW12O40]·15H2O [Ia] with stable three-dimensional micropores and a minimum aperture of 3.3 Å was synthesized with a phosphododecatungstate [α-PW12O40](3-) (polyoxometalate, POM) and a macrocation with acrylate ligands [Cr3O(OOCCH═CH2)6(H2O)3](+). The porous structure of Ia was basically constructed by an arrangement of macrocations forming a six-membered ring: vinyl groups (CH═CH2) of adjacent macrocations were aligned parallel to each other, suggesting a weak dispersion force between them. A guest-free phase [Cr3O(OOCCH═CH2)6(H2O)3]3[α-PW12O40] [Ib] was formed by the treatment of Ia in vacuo at room temperature without any structure change. Compound Ib showed shape-selective sorption of CO2 and C2H2 (molecular size = 3.3 Å) over N2 (3.6 Å) and methane (3.7 Å), and the sorption enthalpy of C2H2 was larger than that of CO2. The high affinity toward C2H2 was further confirmed as follows: the Monte Carlo simulations of the optimized geometries of C2H2 in Ib showed that both hydrogen atoms were in the vicinity of the surface oxygen atoms of POMs. The gas sorption profiles showed a much faster diffusion for C2H2. All these results suggest that the anion and cation mainly play the guest-binding and structure-directing roles, respectively, (i.e., concerted functions) in an ionic crystal with stable three-dimensional micropores.

Two New 2D POMs‐Based Inorganic‐Organic Hybrid Compounds Constructed from the Proline and 4,4’‐Bipy Mixed Ligands

“…K 5 [BW 12 O 40 ]•15H 2 O was prepared according to the literature. K 5 [BW 12 O 40 ]•15H 2 O was prepared according to the literature.…”

“…[1][2][3][4][5][6] Recent research interest is driven mainly by the introduction of abundant organic ligands or transition metal ions into POMs system, in turn, yielding new inorganic-organic hybrid compounds with different structures. [17][18][19] Among these polyoxoanions, a few interesting functionalized POMbased compounds by directly connecting organic ligands with [BW 12 O 40 ] 5 anion have been successfully reported. [17][18][19] Among these polyoxoanions, a few interesting functionalized POMbased compounds by directly connecting organic ligands with [BW 12 O 40 ] 5 anion have been successfully reported.…”

“…[7][8][9][10][11][12][13][14][15][16] It is noteworthy that the Keggin-type polyoxoanions have been mostly employed as inorganic building blocks to construct POMs-based hybrid compounds due to their stable structure, big electron density and potential values. For example, Li et al [20] 12 O 40 ]•5H 2 O (2) (L o ＝ 1,2-bppmb and L p ＝ 1,4bppmb), and these compounds showed good photocatalytic properties for Rhodamine B (RhB) degradation. For example, Li et al [20] 12 O 40 ]•5H 2 O (2) (L o ＝ 1,2-bppmb and L p ＝ 1,4bppmb), and these compounds showed good photocatalytic properties for Rhodamine B (RhB) degradation.…”

“…[17][18][19] Among these polyoxoanions, a few interesting functionalized POMbased compounds by directly connecting organic ligands with [BW 12 O 40 ] 5 anion have been successfully reported. Our group [21] also obtained one new compound [Cu II 2 (phen) 2 (4,4'-bipy)(BW 12 Proline as an interesting amino acid, is inexpensive, nontoxic, readily available and has potential applications in medical science and biological science. Our group [21] also obtained one new compound [Cu II 2 (phen) 2 (4,4'-bipy)(BW 12 Proline as an interesting amino acid, is inexpensive, nontoxic, readily available and has potential applications in medical science and biological science.…”

“…Whereas, the limited coordination sites and preferred chelating coordination modes to metal ions often make it very difficult to yield high-dimensional architectures. [31] On the basis of the aforementioned points, we adopted the proline and 4,4'-bipy as mixed ligands to react with K 5 [BW 12 A large number of hybrid compounds based on POMs containing 4,4'-bipy ligands have been reported.…”