Inorganics

Tumor-mediated hypoxia resistance severely limits the therapeutic efficacy of conventional platinum-based drugs against oral cancer. Targeting carbonic anhydrase IX (CA IX), which is specifically overexpressed in hypoxic tumor cells, represents an effective strategy to reverse chemoresistance. In this work, a novel CA IX-targeting platinum(II) complex was synthesized using pyridoxal 4-sulfamoylphenylhydrazone as the ligand. Single-crystal X-ray diffraction reveals its stable square-planar coordination geometry in the solid state. Enzymatic assays revealed that the complex exhibited negligible inhibition toward the normal CA II isoform and displayed potent inhibitory activity against CA IX (K_i = 26.5 nM), superior to the ligand and the positive control compound U-104. Molecular docking suggests its stable binding to the active pocket of CA IX. In vitro assays exhibited notable hypoxia-selective cytotoxicity against oral cancer HSC-2 cells, with an IC₅₀ value of 3.7 ± 0.2 μM under hypoxic conditions. Mechanistic investigations suggest that the complex may induce oral cancer cell death partly by elevating intracellular reactive oxygen species (ROS) levels and activating the mitochondrial-mediated apoptotic pathway. It should be noted that the solution-state behavior, aquation, and hydrolysis of this platinum complex have not been experimentally explored in the present study; thus, the biologically active platinum-containing species remains uncharacterized, and the observed bioactivity cannot be unequivocally assigned to the intact solid-state complex. This study provides new insights and experimental support for the development of hypoxia-responsive platinum-based agents targeting CA IX against oral cancer.

Two key reactions in the synthesis of a difunctionalized tris-cyclometallated iridium complex [Ir(ppy-Br)₂fppy] (3), which is an important intermediate for the synthesis of more sophisticated iridium complexes, were investigated to improve performance. The first reaction is the formation of a monomeric iridium complex [Ir(ppy)₂fppy] (2), and the second reaction is the bromination of complex 2 to yield the bifunctional complex 3. The performance of these reactions during our previous work was suboptimal (e.g., formation of side products, reproducibility issues). A response surface methodology (RSM) investigation of the first reaction provided information to avoid the failures we experienced previously. Investigation of the second reaction showed us that its reaction time could be shortened from 18 h to 3 min and the reaction temperature decreased from 90 °C to 0 °C. This enabled controllable synthesis of the desired complex 3 with an improved yield (87%). Furthermore, investigation of the second reaction led to the identification of conditions for the synthesis of the monobrominated complex [[Ir(ppy)(ppy-Br)(fppy)] (5). Finally, complexes 3 and 5 were modified via Suzuki–Miyaura coupling and reduction to yield complexes 7 and 9, to demonstrate their value as intermediates for further transformations. The photophysical properties of complexes 7 and 9 were investigated and compared with those of their parent structure, complex 10.

Twelve nominal ABO₃ compositions, where A = La, Y, Lu and B = Al, Ga, Sc, In, were synthesized by the sol-gel method and annealed at 700–1300 °C. The phase formation behavior was evaluated using tolerance factor calculations, XRD, Rietveld refinement, FTIR, SEM, SEM-EDX, and ICP-OES analysis. La-based compounds showed the highest tendency to form perovskite phases, while Y-based samples revealed strongest phase competition, and Lu-based materials mainly formed non-perovskite structures. LuScO₃ and LuInO₃ have a cubic bixbyite-type structure, whereas LuAlO₃ and LuGaO₃ formed garnet and Lu₂O₃ oxide-containing mixtures. The FTIR results confirmed the formation of metal–oxygen bonds during annealing, while SEM revealed agglomerated and porous powders with composition-dependent differences in apparent morphological feature size. SEM-EDX mapping revealed homogeneous elemental distributions, while ICP-OES confirmed that the A/B cation ratios remained close to the nominal ABO₃ stoichiometry, suggesting that the secondary phase formation was mainly related to phase stability rather than deviation in composition.