Stability investigation of some heteropolyoxotungstate and heteropolyoxomolybdate salts in buffer solutions

Polyoxometalates in solution: speciation under spotlight

“…198 Heteropolyanions with protonated amino acids as cations can be stable up to pH 6.2, which can provide valuable insights for correct application of these POMos in medical usage. 199 In general, complexes based on lacunary HPOMos are more unstable in aqueous solution than, for example, their tungsten analogs, 197 and there is still insufficient data on lacunary HPOMos stability in solution. Heteropolymolybdates follow a generally accepted trend -the substitution of addenda atoms with transition metals in Keggin clusters reduces the net charge and stabilizes therewith the anions (Table 8) Fig.…”

The use of polyoxometalates in protein crystallography – An attempt to widen a well-known bottleneck

“…Among them, the Keggin-type ([PW 12 O 40 ] 3− , [PMo 12 O 40 ] 3− , [W 12 O 40 H 2 ] 6− ), Wells–Dawson-type ([P 2 W 18 O 62 ] 6− ), Anderson-type ([TeW 6 O 24 ] 6− ), decavanadate ([V 10 O 28 ] 6− ), cyclotetravanadate ([V 4 O 12 ] 4− ), octamolybdate ([Mo 8 O 28 ] 8− ) and heptamolybdate ([Mo 7 O 24 ] 6− ). The appearance of these POM structures was mostly the result of crystallization in solutions containing addenda oxoanions (MoO 4 2− , VO 4 3− or WO 4 2− ) under conditions promoting the spontaneous self-assembly of common POM species or their addition on purpose [24,102–105] . However, several PDB entries contain POMs with sum formulas so far only seen as part of protein structures like [Mo 6 O 27 H n ] n −18 , [Mo 8 O 26 O(Glu)N(His)H n ] n −5 , [W 3 O 10 H n N 3 ] (6− n )− and [Mo 3 O 14 ] 10− .…”

PVP-stabilized heteropolyacids as reusable self-assembling catalysts for alcoholysis of cellulosic saccharides

“…Although PVP-HPW (1/5 : 1) exhibits reusable catalyzing performance, it still falls short of our objectives. According to the published report, the SiW anion has better stability than the PW anion in the liquid phase, 25 so HPW is substituted with HSiW to synthesize PVP-HSiW (1/5 : 3/4). Similar to PVP-HPW (1/5 : 1), PVP-HSiW (1/5 : 3/4) exhibits remarkable activity in the alcoholysis of cellobiose and cellulose (entries 10A and B).…”