Aluminum-Substituted Keggin Germanotungstate [HAl(HO)GeWO]: Synthesis, Characterization, and Antibacterial Activity.

We report on the new monosubstituted aluminum Keggin-type germanotungstate (CHN)[HAlGeWO(HO)]·11HO (), which has been synthesized at room temperature via rearrangement of the dilacunary [γ-GeWO] polyoxometalate precursor. has been characterized thoroughly both in the solid state by single-crystal and powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis, and elemental analysis as well as in solution by cyclic voltammetry (CV) W, Al NMR and UV-vis spectroscopy. A study on the antibacterial properties of and the known aluminum(III)-centered Keggin polyoxotungstates (Al-POTs) α-Na[AlWO] () and Na[Al(AlOH)WO] () revealed enhanced activity for all three Al-POTs against the Gram-negative bacterium (minimum inhibitory concentration (MIC) up to 4 μg mL) and the Gram-positive (MIC up to 128 μg mL) compared to the inactive Al(NO) salt (MIC > 256 μg mL). CV indicates the redox activity of the Al-POTs as a dominating factor for the observed antibacterial activity with increased tendency to reduction, resulting in increased antibacterial activity of the POT.