Proton-Conductive Polyoxometalate Architectures Constructed from Lanthanide-Incorporated Polyoxoniobate Cages

Abstract

Two new extended polyoxometalate (POM) architectures based on lanthanide-incorporated polyoxoniobate (Ln-incorporated PONb) cages, namely, H4[CuII(en)2]4{K4(H2O)2­[CuII(en)2]5[CuII 5­​(trz)2(en)4(OH)2]­[Dy2CuII 2­(en)2(CO3)3­(H2O)2(OH)3]­[Dy­(H2O)4]­[Dy­Nb23O68­(H2O)4]2}·60H2O (1, en = ethylenediamine) and H20[CuII(en)2]4­{[CuII(en)2]4­[Dy2(C2O4)­(H2O)4]2­[(Nb32(OH)4­(H2O)3­O89]2}·54H2O (2), have been successfully synthesized and structurally characterized, demonstrating a feasible strategy to develop functional POM materials. In addition, the proton conductivity and magnetic behaviors of both 1 and 2 were studied.

Development of a New Heteropolyoxotantalate Cluster for Multidimensional Polyoxotantalate Materials

“…It is probably because of the accelerated velocity of water molecules in the channels with the increase of temperature. , By use of the Arrhenius equation σ T = σ 0 exp­(− E a / k b T ), the activation energy ( E a ) was assessed. The linear regression analysis shows that the E a of 1 was 1.03 eV (Figure S15), which follows the vehicular mechanism (>0.4 eV) . Powder X-ray diffraction characterization suggests that the crystallinity of 1 remains undamaged after proton conduction measurement (Figure d).…”

“…The linear regression analysis shows that the E a of 1 was 1.03 eV (Figure S15), which follows the vehicular mechanism (>0.4 eV). 40 Powder X-ray diffraction characterization suggests that the crystallinity of 1 remains undamaged after proton conduction measurement (Figure 4d). The conductivity of 1 is a little higher than that of the other two organic−inorganic POTa clusters we have recently reported, 41 probably because 1 exhibits a one-dimensional chain structure while the reported two compounds are isolated structures.…”

Hexameric polyoxotantalate with proton conduction properties

“…Remarkably, 1 shows excellent proton conductivity at 85 1C and 85% RH, and the proton conductivity is superior to most proton-conducting POMs reported. 5,[47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63] Moreover, there is no structural transformation after the impedance measurement, which was confirmed by PXRD (Fig. S9, ESI †).…”

Decaniobate: The Fruit Fly of Niobium Polyoxometalate Chemistry

“…The second Ln-substituted Nb-POM, denoted Nd–Nb 48 CO 3 , [(Nd 2 O 5 (Nb 7 O 22 ) 6 (CO 3 )­(NbO­(H 2 O)) 6 ] 42– , Figure C) can be described as two NdNb 23 rings, with a Nd 3+ replacing one of the three bridging [H 2 O---NbO] 3+ units within a typical Nb 24 ring. Recently, the group of S. T. Zheng reported a very similar Dy 3+ substitution of [H 2 O---NbO] 3+ within the Nb 24 units, building fantastic Nb–Dy frameworks. ,, With the modification of this family, Zheng identified the first evidence for reduced Nb within an Nb-POM . Notably these were obtained by more typical Nb-POM syntheses that involve hexaniobate starting materials, hydrothermal processing, and several other reagents including Cu-ethylenediamine cations, oxalate, and triazole, where Cu and oxalate are included in the crystallized lattices.…”