Polyoxoplatinates as covalently dynamic electron sponges and molecular electronics materials

In organic systems, dynamic covalent chemistry provides an adaptive approach (i.e., "covalent dynamics") where thermodynamic equilibria are used to tailor structural and electronic changes in molecular assemblies. The covalent dynamics finds utility in the design of novel self-healing materials, sensors, and actuators. Herein, using density functional theory (DFT) we explore the structural, electronic and transport properties of the Pt-based polyoxometalate (POM) [Pt^III ₁₂O₈(SO₄)₁₂]^4- and its derivatives. The latter POM has six redox responsive {O-Pt-Pt-O} moieties and prospects for storage of up to twelve electrons, thus exemplifying how dynamic covalent chemistry may manifest itself in fully inorganic systems. Simulations of the Au/POM/Au junction show that the electron conduction strongly depends on the redox of the POM but more weakly on its rotations with respect to the Au surface. Moreover, the POM shows promising spin-polarized current behaviour, which can be modulated using bias and gate voltages.

{BiW8 O30 } Exerts Antitumor Effect by Triggering Pyroptosis and Upregulating Reactive Oxygen Species

We successfully synthesized {BiW8 }, a 10-nuclear heteroatom cluster modified {BiW8 O30 }. At 24 h post-incubation, the IC50 values of {BiW8 } against HUVEC, MG63, RD, Hep3B, HepG2, and MCF7 cells were 895.8, 127.3, 344.3, 455.0, 781.3, and 206.3 μM, respectively. The IC50 value of {BiW8 } on the MG63 cells was more than 2-fold lower than that of the other raw materials. Through morphological and functional features, we demonstrated pyroptosis as a newly identified mechanism of cell death induced by {BiW8 }. {BiW8 } increased 2-fold reactive oxygen species (ROS) levels in MG63 cells at 24 h post-incubation. Compared with 0 h, the glutathione (GSH) content decreased by 59, 65, 75, 94, and 97 % at 6, 12, 24, 36 and 48 h post-incubation, respectively. Furthermore, multiple antitumor mechanisms of {BiW8 } were identified via transcriptome analysis and chemical simulation, including activation of pyroptosis, suppression of GSH generation, depletion of GSH, and inhibition of DNA repair.

Adsorption of Keggin-Type Polyoxometalates on Rh Metal Particles under Reductive Conditions

The adsorption of POMs on Rh/SiO₂ in water solvent under strongly reductive conditions was investigated. Aqueous solutions of α-Keggin type silicotungstate and silicovanadotungstates were mixed with Rh/SiO₂ at 393-473 K under 1 MPa of H₂. Monovanadium-substituted silicotungstate, α-SiVW₁₁O₄₀^5- (SiVW₁₁), was more readily adsorbed than nonsubstituted silicotungstate, α-SiW₁₂O₄₀^4- (SiW₁₂). After adsorption at 433 K, SiVW₁₁ was desorbed from Rh/SiO₂ by oxidation with Br₂ water without change of the Keggin structure, as evidenced by ⁵¹V NMR. Trivanadium-substituted silicotungstate, α-1,2,3-SiV₃W₉O₄₀^7-, was not stable, and the desorbed species from Rh/SiO₂ by oxidation with Br₂ did not maintain the Keggin structure. The very high temperature for adsorption (473 K) also led to the decomposition of the Keggin structure of SiVW₁₁. An increase in the concentration of SiVW₁₁ in the liquid phase gave a saturation of the amount of desorbable SiVW₁₁, up to five SiVW₁₁ anions per one Rh particle with a 3 nm size. The elemental analysis and W L₃-edge extended X-ray absorption fine structure of Rh/SiO₂ after the adsorption of SiVW₁₁ showed that a part of SiVW₁₁ was decomposed and irreversibly adsorbed as metallic W species incorporated into the surface of Rh metal particles. The amount of decomposed SiVW₁₁ was almost the same as that of SiVW₁₁ adsorbed as the original Keggin structure. The desorbable SiVW₁₁ was probably bonded on the W atom incorporated on the Rh metal particles as the two-electron-reduced form (α-SiV^IIIW₁₁O₄₀^7-).