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Due to their high abundance, polymeric character, and chemical tunability, polysaccharides are perfect candidates for the stabilization of photoactive nanoscale objects, which are of great interest in modern science but can be unstable in aqueous media. In this work, we have demonstrated the relevance of oxidized dextran polysaccharide, obtained via a simple reaction with H₂O₂, towards the stabilization of photoactive octahedral molybdenum and tungsten iodide cluster complexes [M₆I₈}(DMSO)₆](NO₃)₄ in aqueous and culture media. The cluster-containing materials were obtained by co-precipitation of the starting reagents in DMSO solution. According to the data obtained, the amount and ratio of functional carbonyl and carboxylic groups as well as the molecular weight of oxidized dextran strongly affect the extent of stabilization, i.e., high loading of aldehyde groups and high molecular weight increase the stability, while acidic groups have some negative impact on the stability. The most stable material based on the tungsten cluster complex exhibited low dark and moderate photoinduced cytotoxicity, which together with high cellular uptake makes these polymers promising for the fields of bioimaging and PDT. Full article

Emissions of various organic pollutants in the environment becomes a more and more acute problem in the modern world as they can lead to an ecological disaster in foreseeable future. The current situation forces scientists to develop numerous methods for the treatment of polluted water. Among these methods, advanced photocatalytic oxidation is a promising approach for removing organic pollutants from wastewater. In this work, one of the most common photocatalysts—titanium dioxide—was obtained by direct aqueous hydrolysis of titanium (IV) isopropoxide and impregnated with aqueous solutions of octahedral cluster complexes [{M₆I₈}(DMSO)₆](NO₃)₄ (M = Mo, W) to overcome visible light absorption issues and increase overall photocatalytic activity. XRPD analysis showed that the titania is formed as anatase-brookite mixed-phase nanoparticles and cluster impregnation does not affect the morphology of the particles. Complex deposition resulted in the expansion of the absorption up to ~500 nm and in the appearance of an additional cluster-related band gap value of 1.8 eV. Both types of materials showed high activity in the photocatalytic decomposition of RhB under UV- and sunlight irradiation with effective rate constants 4–5 times higher than those of pure TiO₂. The stability of the catalysts is preserved for up to 5 cycles of photodegradation. Scavengers’ experiments revealed high impact of all of the active species in photocatalytic process indicating the formation of an S-scheme heterojunction photocatalyst. Full article

Despite that the chemistry of octahedral cluster complexes has been actively developed recently, there are still a lot of unexplored areas. For example, to date, only a few halide M₆-clusters with N-heterocycles are known. Here, we obtained an apically heteroleptic octahedral iodide molybdenum cluster complex with pyridine ligands—trans-[{Mo₆I₈}(py)₂I₄] by the direct substitution of iodide apical ligands of [{Mo₆I₈}I₆]^2– in a pyridine solution. The compound co-crystalized with a monosubstituted form [{Mo₆I₈}(py)I₅]^– in the ratio of 1:4, and thus, can be described by the formula (pyH)_0.2[{Mo₆I₈}(py)_1.8I_4.2]·1.8py. The composition was studied using XRPD, elemental analyses, and ¹H-NMR and IR spectroscopies. According to the absorption and luminescence data, the partial substitution of apical ligands weakly affects optical properties. Full article