Determination of the protonation state of [H3PW11O39]4− and the stability constant of [Ag(H2O)(H3PW11O39)]3− in aqueous solution

Wang, Jidan; Li, Jian-Sheng; You, Weixiong; He, Chunnian; Zhu, Zai‐Ming

doi:10.1080/00958972.2016.1218000

Cited by 3 publications

(1 citation statement)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the oxygen atoms surrounding the lacuna are much more basic than the bridging and terminal atoms and most likely protonated to a certain extent 54 . In neutral aqueous solution, binding of up to three protons was suggested for [SiW 11 O 39 ] 8− and confirmed by conductivity measurements for [PW 11 O 39 ] 7− , resulting in the predominant species H 3 [PW 11 O 39 ] 4− 55 . This POT species with a surface charge distribution similar to [SiW 12 O 40 ] 4− is therefore responsible for most of the inhibitory capacity found for the [PW 12 ] 3− and [PW 11 ] 7− setups.…”

Section: Resultsmentioning

confidence: 76%

Keggin-type polyoxotungstates as mushroom tyrosinase inhibitors - A speciation study

Breibeck

Gumerova

Boesen

et al. 2019

Sci Rep

View full text Add to dashboard Cite

Mushroom tyrosinase abPPO4 is a commercially relevant polyphenol oxidase and has been being targeted for numerous inhibition studies including polyoxometalates (POMs). In the present work, its diphenolase activity was inhibited at pH 6.8 by a series of structurally related polyoxotungstates (POTs) of the α-Keggin archetype, exhibiting the general formula [Xn+W12O40](8−n)− in order to elucidate charge-dependent activity correlations. Kinetic data were obtained from the dopachrome assay and 183W NMR was applied to obtain crucial insights into the actual Keggin POT speciation in solution, facilitating a straightforward assignment of inhibition effects to the identified POT species. While [PW12O40]3− was completely hydrolyzed to its moderately active lacunary form Hx[PW11O39](7−x)− (Ki = 25.6 mM), [SiW12O40]4− showed the most pronounced inhibition effects with a Ki of 4.7 mM despite of partial hydrolysis to its ineffective lacunary form Hx[SiW11O39](8−x)−. More negative Keggin cluster charges of 5− and 6− generally resulted in preclusion of inhibitory efficacy as well as hydrolysis, but with the Ni-substituted cluster [PW11O39{Ni(H2O)}]5− enzymatic inhibition was clearly restored (Ki = 9.7 mM). The inhibitory capacity of the structurally intact Keggin POTs was found to be inversely correlated to their net charge. The here applied speciation strategy is of utmost importance for any biological POM application to identify the actually active POM species.

show abstract

Section: Resultsmentioning

confidence: 76%