A 60-year-old mystery solved: the average structures of alkali polytungstates A₄W₁₁O₃₅ and A₂W₇O₂₂ (A = K, Rb, Cs) related to hexagonal tungsten bronze were determined.

New compounds of the composition Na5Rb7Sc2(XO4)9 (X = Mo, W) were obtained via the ceramic technology. The sequences of chemical transformations occurring during the formation of these compounds were established, and their primary characterization was performed. Both Na5Rb7Sc2(XO4)9 (X = Mo, W) were found to melt incongruently at 857 K (X = Mo) and 889 K (X = W). They are isostructural to Ag5Rb7Sc2(XO4)9 (X = Mo, W), Na5Cs7Ln2(MoO4)9 (Ln = Tm, Yb, Lu) and crystallize in the trigonal crystal system (sp. gr. R32). The crystal structures were refined with the Rietveld method using the powder X-ray diffraction data. The thermal expansion of Na5Rb7Sc2(WO4)9 was studied by high-temperature powder X-ray diffraction; it was shown that this triple tungstate belongs to high thermal expansion materials.

A novel acridine-based fluorescent sensor (Sensor ANT) for the highly selective and sensitive detection of cyanide ions (CN⁻) was rationally designed and synthesized via the conjugation reaction of acridine-9-amine with 3-nitrophenyl isothiocyanate. The sensing mechanism is triggered by the specific interaction between exogenous CN⁻ and the hydrogen-bonding moieties within the sensor’s molecular framework, which induces a distinct fluorescence quenching response. Systematic titration experiments confirmed that Sensor ANT exhibits rapid response kinetics, excellent selectivity, and reliable qualitative/quantitative detection capabilities toward CN⁻. Complementary biocompatibility assays, including in vitro cellular imaging and in vivo zebrafish experiments, further verified the promising application potential of this sensor in practical and biological detection scenarios. The detection limit (DL) of Sensor ANT for CN⁻ was calculated to be 2.89 × 10⁻⁷ M, with a 1:1 binding stoichiometry and a binding constant of 1.95 × 10⁴ M⁻¹. These findings demonstrate that Sensor ANT represents a robust candidate for CN⁻ detection in environmental and biological systems.

The present study is aimed at the directed synthesis of a new ternary molybdate K₅Pb_0.5Zr_1.5(MoO₄)₆ isostructural to K₅Pb_0.5Hf_1.5(MoO₄)₆ by solid-phase reaction within the temperature range of 350–550 °С (for 100 h). The compound crystallizes in the rhombohedral system with the space group R3̅ and unit cell parameters of a = 10.6604(2) Å, c = 37.9769(9) Å, and V = 3737.6(2) ų. The structure was refined using the Rietveld method. The atomic positions were refined in the isotropic approximation, with soft constraints on Mo–O distances and O–Mo–O bond angles. The crystal structure constitutes a 3D scaffold comprising PbO₆ and ZrO₆ octahedrons and MoO₄ tetrahedrons sharing oxygen vertices. The thermal expansion of K₅Pb_0.5Zr_1.5(MoO₄)₆ was studied via high-temperature X-ray powder diffraction. The calculated thermal expansion coefficients along both crystallographic axes remain positive over the entire temperature range. In this case, the value of α_a remains constant, while that of α_c increases with rising temperature. The obtained ternary molybdate belongs to materials with high thermal expansion (α_V = 60×10^-6 °С^-1). The significant anisotropy in the crystallographic direction c can be attributed to the soft K–O and Pb-O bonds. The electrical conductivity of K₅Pb_0.5Zr_1.5(MoO₄)₆ was studied via impedance spectroscopy within the temperature range of 30–500 °С; at 500 °С, the conductivity amounted to 0.7×10^-4 S/cm, with E_a = 0.59 eV.