In Vitro Antibacterial Susceptibility of Different Pathogens to Thirty Nano-Polyoxometalates

Due to their unique properties, nano-polyoxometalates (POMs) can be alternative chemotherapeutic agents instrumental in designing new antibiotics. In this research, we synthesized and characterized “smart” nanocompounds and validated their antibacterial effects in order to formulate and implement potential new drugs. We characterized thirty POMs in terms of antibacterial activity–structure relationship. The antibacterial effects of these compounds are directly dependent upon their structure and the type of bacterial strain tested. We identified three POMs that presented sound antibacterial activity against S. aureus, B. cereus, E. coli, S. enteritidis and P. aeruginosa strains. A newly synthesized compound K₆[(VO)SiMo₂W₉O₃₉]·11H₂O (POM 7) presented antibacterial activity only against S. aureus (ATCC 6538P). Twelve POMs exerted antibacterial effects against both Gram-positive and Gram-negative strains. Only one POM (a cluster derivatized with organometallic fragments) exhibited a stronger effect compared to amoxicillin. New studies in terms of selectivity and specificity are required to clarify these extremely important aspects needed to be considered in drug design.

Metal-Catalyzed Degradation of Cellulose in Ionic Liquid Media

Biomass conversion to 5-hydroxymethylfurfural (HMF) has been widely investigated as a sustainable alternative to petroleum-based feedstock, since it can be efficiently converted to fuel, plastic, polyester, and other industrial chemicals. In this report, the degradation of commercial cellulose, the isomerization of glucose to fructose, and the conversion of glucose to HMF in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl]) using metal catalysts (CrCl3, ZnCl2, MgCl2) as well as tungsten and molybdenum oxide-based polyoxometalates (POM) were investigated. Tungsten and molybdenum oxide-based POMs in ionic liquids (IL) were able to degrade cellulose to majority glucose and epimerize glucose to mannose (in the case of the molybdenum oxide-based POM). A certain amount of glucose was also converted to HMF. The tungsten oxide-based POM in IL showed good activity for cellulose degradation but the overall products yield remained 28.6% lower than those obtained using CrCl3 as a catalyst. Lowering the cellulose loading did not significantly influence the results and the addition of water to the reaction medium decreased the product yields remarkably.

Heterogeneous catalysis by tungsten-based heteropoly compounds

In this review, the recent works on heterogeneous catalytic applications of polyoxotungstates in liquid-phase organic reactions are reviewed.

Synthesis and characterization of metal-substituted tetraalkylphosphonium polyoxometalate ionic liquids

Trihexyl(tetradecyl)phosphonium and Keggin polyoxotungstates [PW₁₁O₃₉M(H₂O)]ⁿ⁻, M = Fe, Co, Mn, or related lacunary [PW₁₁O₃₉]⁷⁻ and [P₂W₂₀O₇₀(H₂O)₂]¹⁰⁻ anions yield compounds that are liquids at room temperature.