Modulation of acetylcholinesterase activity induced by polyoxotungstates

The in vitroinfluence of five polyoxotungstates containing various central atoms on acetylcholinesterase (AChE) activity was investigated. K6[PV3W9O40] × 3H2O, K6H2[TiW11CoO40] × 13H2O, (NH4)14[NaP5W30O110] × 31H2O, K7[SiV3W9O40] × 10H2O, and K7[Ti2PW10O40] induced the enzyme inhibition in a concentration-dependent manner. Inhibitory power of the investigated compounds was evaluated using IC50values. K7[SiV3W9O40] × 10H2O affected AChE activity with lowest potency (IC50 = 4.80 × 10-4mol/L). K6H2[TiW11CoO40] × 13H2O and K7[Ti2PW10O40] exhibited high affinity toward the enzyme, inducing half-maximuminhibition at micromolar concentrations (1.14 × 10-6and 1.04 × 10-6mol/L, respectively), while the same effect was achieved in the presence of about fifty times higher concentration of K6[PV3W9O40] × 3H2O. Finally, (NH4)14[NaP5W30O110] × 31H2O was foundas the most potent inhibitor of AChE activity (IC50 = 6.36 × 10-7mol/L), and consequently the most promising candidate for the treatment of neurological diseases associated with acetylcholine leakage.Physical chemistry 2016 : 13th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-30 September 2016

NiII^{II}36_{36}-Containing 54-Tungsto-6-Silicate: Synthesis, Structure, Magnetic and Electrochemical Studies

The 36-Ni$^{II}$-containing 54-tungsto-6-silicate, [Ni$_{36}$(OH)$_{18}$(H$_{2}$O)$_{36}$(SiW$_{9}$O$_{34}$)$_{6}$]$^{6-}$ (Ni$_{36}$) was synthesized by a simple one-pot reaction of the Ni$_{2}$-pivalate complex [Ni$_{2}$(μ-OH$_{2}$)(O$_{2}$CCMe$_{3}$)$_{4}$(HO$_{2}$CCMe$_{3}$)$_{4}$] with the trilacunary [SiW$_{9}$O$_{34}$]$^{10-}$ polyanion precursor in water and structurally characterized by a multitude of physicochemical techniques including single-crystal XRD, FTIR, TGA, elemental analysis, magnetic and electrochemical studies. Polyanion Ni$_{36}$ comprises six equivalent {Ni$^{II}$$_{36}$SiW$_{9}$} units which are linked by Ni−O−W bridges forming a macrocyclic assembly. Magnetic studies demonstrate that the {Ni$_{6}$} building blocks in Ni$_{36}$ remain magnetically intact while forming a hexagonal ring with antiferromagnetic exchange interactions between adjacent {Ni6} units. Electrochemical studies indicate that the first reduction is reversible and associated with the WVI/V couple, whereas the second reduction is irreversible attributed to the Ni$^{II/0}$ couple

Microwave-assisted fast cyclohexane oxygenation catalyzed by iron-substituted polyoxotungstates

Under microwave irradiation, iron-substituted polyoxotungstates (Fe-POMs) catalyze cyclohexane oxygenation to A/K oil with 90\u201395% selectivity, unmatched turnover frequencies (40\u2013400 h1), and multi-turnover regime (>1000 TON). Such a rapid reaction protocol allowed the screening of so-called inorganic Fe-synzymes with 1 \u2013 4 nuclearity, including a family of Krebs-type isostructural complexes. Product distribution, kinetic analysis, mechanistic probes and fitting calculations, are consistent with a radical chain oxidation propagated by Fe-catalysed decomposition of organic peroxides which ultimately depends on the redox-properties and structural arrangement of the iron moiety within the POM cage

The ball-shaped heteropolytungstates [{Sn(CH3)2(H2O)}24{Sn(CH3)2}12(A-XW9O34)12]36- (X=P, As): stability, redox and electrocatalytic properties in aqueous media

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