engleski

Synthesis, characterization, and phosphoesterase activity of a series of 4f- and 4d-sandwich-type germanotungstates [(n- C4H9)4N]l/mH2[(M(H2O)3)(γ-GeW10O35)2] (M = CeIII, NdIII, GdIII, ErIII, l = 7; ZrIV, m = 6)

We report on a family of five new 4f- and 4d- doped sandwich-type germanotungstates with the general formula [(n- C4H9)4N]l/mH2[(M(H2O)3)(γ- GeW10O35)2]·3(CH3)2CO [M- (H2O)3(GeW10)2] (M = CeIII, NdIII, GdIII, ErIII, l = 7 ; ZrIV, m = 6), which have been synthesized at room temperature in an acetone−water mixture. Among the compound series, [Zr- (H2O)3(GeW10)2] 8−, which has been obtained in the presence of 30% H2O2, represents the first example of a 4d-substituted germanotungstate incorporating the intact dilacunary [γ- GeIVW10O36] 8− building block. All compounds were characterized thoroughly in the solid state by single-crystal and powder X-ray diffraction (XRD), IR spectroscopy, thermogravimetric analysis (TGA), and elemental analysis and in solution by NMR and UV−vis spectroscopy. The phosphoesterase activity of [Ce(H2O)3(GeW10)2] 9− and [Zr(H2O)3(GeW10)2] 8− toward the model substrates 4-nitrophenyl phosphate (NPP) and O, O-dimethyl O-(4- nitrophenyl) phosphate (DMNP) was monitored with 1 Hand 31P-NMR spectroscopy revealing an acceleration of the hydrolytic reaction by an order of magnitude (kcorr = 3.44 (±0.30) × 10−4 min−1 for [Ce(H2O)3(GeW10)2]9− and kcorr = 5.36 (±0.05) × 10−4 min−1 for [Zr(H2O)3(GeW10)2]8−) as compared to the uncatalyzed reaction (kuncat = 2.60 (±0.10) × 10−5 min−1 ). [Ce(H2O)3(GeW10)2]9− demonstrated improved antibacterial activity toward Moraxella catarrhalis (MIC 32 μg/mL), compared to the unsubstituted [GeW10O36]8− POM (MIC 64 μg/mL)

germanotungstates ; chemical synthesis ; phosphoesterase activity ; antibacterial activity ; Moraxella catarrhalis

Bilateral financial funding is provided by the Centre for International Cooperation & Mobility (ICM) of the Austrian Agency for International Cooperation in Education and Research (OeADGmbH) Project No. HR 06/2020 to A.R. and the Project “Biological profiling of polyoxometalates” to Hana Čipčić Paljetak.