Silyl- and germyl-bridged neutral square-planar Ag4 clusters with short Ag-Ag distances exhibiting red emission

We report silyl- and germyl-bridged neutral square-planar Ag4 clusters with very short Ag-Ag distances (2.695 and 2.704 Å), as revealed by single-crystal X-ray diffraction analysis. On the basis of the results of theoretical calculations, we attribute these short distances to attractive Ag-Ag interactions that reduce the optical energy gap, resulting in a red emission reaching wavelengths of up to 700 nm. These wavelengths are among the longest observed for emissions from Ag4 clusters.

Polyoxometalates and their composites for antimicrobial applications: Advances, mechanisms and future prospects

The overuse of antibiotics can lead to the development of antibiotic-resistant bacteria, which can be even more difficult to treat and pose an even greater threat to public health. In order to address the issue of antibiotic-resistant bacteria, researchers currently are exploring alternative methods of sterilization that are both effective and sustainable. Polyoxometalates (POMs), as emerging transition metal oxide compounds, exhibit significant potential in various applications due to their remarkable tunable physical and chemical performance, especially in antibacterial fields. They constitute a diverse family of inorganic clusters, characterized by a wide array of composition, structures and charges. Presently, several studies indicated that POM-based composites have garnered extensive attention in the realms of the antibacterial field and may become promising materials for future medical applications. Moreover, this review will focus on exploring the antibacterial properties and mechanisms of different kinds of organic-inorganic hybrid POMs, POM-based composites, films and hydrogels with substantial bioactivity, while POM-based composites have the dual advantages of POMs and other materials. Additionally, the potential antimicrobial mechanisms have also been discussed, mainly encompassing cell wall/membrane disruption, intracellular material leakage, heightened intracellular reactive oxygen species (ROS) levels, and depletion of glutathione (GSH). These findings open up exciting possibilities for POMs as exemplary materials in the antibacterial arena and expand their prospective applications.

Hybrid Antimicrobial Films Containing a Polyoxometalate-Ionic Liquid

The increasing resistance of pathogenic microorganisms against common treatments requires innovative concepts to prevent infection and avoid long-term microbe viability on commonly used surfaces. Here, we report the preparation of a hybrid antimicrobial material based on the combination of microbiocidal polyoxometalate-ionic liquids (POM-ILs) and a biocompatible polymeric support, which enables the development of surface coatings that prevent microbial adhesion. The composite material is based on an antibacterial and antifungal room-temperature POM-IL composed of guanidinium cations (N,N,N',N'-tetramethyl-N″, N″-dioctylguanidinum) combined with lacunary Keggin-type polyoxotungstate anions, [α-SiW₁₁O₃₉]^8-. Integration of the antimicrobial POM-IL into the biocompatible, flexible, and stable polymer poly(methyl methacrylate) (PMMA) results in processable films, which are suitable as surface coatings or packaging materials to limit the proliferation and spread of pathogenic microorganisms (e.g., on public transport and hospital surfaces, or in ready-to-eat-food packaging).

Recent advances in polyoxometalate-based metal-alkynyl clusters

This paper focuses on the recent advances in polyoxometalate-based metal-alkynyl clusters.

Synthesis and characterization of a nanocluster-based silver(i) tert-butylethynide compound with a large second-harmonic generation response

A new nanocluster-based silver(i) tert-butylethynide compound, namely, (tBuC[triple bond, length as m-dash]CAg)2(Ag4SiW12O40)(DMSO)6 (HT-1), has been synthesized and structurally characterized by X-ray crystallography. The two kinds of nanocluster synthons (a silver aggregate named [(tBuC[triple bond, length as m-dash]C)2Ag6(DMSO)6] and a SiW12 polyoxoanion) are assembled into a three-dimensional coordination network, which has a non-centrosymmetric crystal lattice. Powder second-harmonic generation (SHG) measurements reveal that HT-1 belongs to the phase-matchable class with a moderately strong SHG response of about 3 times that of the KH2PO4 (KDP) sample. HT-1 represents the first example of a Ag(i) alkynyl cluster compound with a SHG response. The present study not only extends the application fields of Ag(i) alkynyl clusters but also demonstrates a new paradigm for understanding the Ag(i) alkynyl structural chemistry.

Combating pathogens with Cs2.5H0.5PW12O40 nanoparticles: a new proton-regulated antimicrobial agent

The transfer of pathogens from contaminated surfaces to patients is one of the main causes of health care-associated infections (HCAIs). Cases of HCAIs due to multidrug-resistant organisms have been growing worldwide, whereas inorganic nano-antimicrobials are valuable today for the prevention and control of HCAIs. Here, we present a cesium salt of phosphotungstic heteropolyacid (Cs_2.5H_0.5PW₁₂O₄₀) as a promising nanomaterial for use in antimicrobial product technologies. This water-insoluble Keggin salt exhibits a broad biocide spectrum against Gram-positive and Gram-negative bacteria, yeasts, and filamentous fungi even under dark conditions. The Cs_2.5H_0.5PW₁₂O₄₀ nanoparticles (NPs) act as a proton-regulated antimicrobial whose activity is mediated on the release of hydronium ions (H₃O⁺), yielding an in situ acidic pH several units below those tolerable by most of the fungal and bacterial nosocomial pathogens.