Gallium(III)- and Thallium(III)-Encapsulated Polyoxopalladates: Synthesis, Structure, Multinuclear NMR, and...

Three gallium(III)- and thallium(III)-containing polyoxopalladates (POPs) have been synthesized and structurally characterized in the solid state and in solution, namely, the phosphate-capped 12-palladate nanocubes [XPd₁₂O₈(PO₄)₈]^13- (X = Ga^III, GaPdP; X = Tl^III, TlPdP) and the 23-palladate double-cube [Tl₂^IIIPd₂₃P₁₄O₇₀(OH)₂]^20- (TlPdP). The cuboid POPs, GaPdP and TlPdP, are solution stable as verified by the respective ³¹P, ⁷¹Ga, and ²⁰⁵Tl nuclear magnetic resonance (NMR) spectra. Of prime interest, the spin-spin coupling schemes allowed for an intimate study of the solution behavior of the Tl^III-containing POPs via a combination of ³¹P and ²⁰⁵Tl NMR, including the stoichiometry of the major fragments of TlPdP. Moreover, biological studies demonstrated the antitumor and antiviral activity of GaPdP and TlPdP, which were validated to be as efficient as cis-platinum against human melanoma and acute promyelocytic leukemia cells. Furthermore, GaPdP and TlPdP exerted inhibitory activity against two herpetic viruses, HSV-2 and HCMV, in a dose-response manner.