Gallium(III)- and Thallium(III)-Encapsulated Polyoxopalladates: Synthesis, Structure, Multinuclear NMR, and Biological Activity Studies

The phosphate-capped 12-palladate nanocubes[XPd12O8(PO4)(8)](13-) (X= Ga-III, GaPd ( 12 ) P ( 8 ); X = Tl-III, TlPd ( 12 ) P ( 8 )) and the 23-palladate double-cube [Tl-2 (Pd23P14O70)-Pd-III(OH)(2)](20-) (Tl ( 2 ) Pd ( 23 ) P ( 14 )) have beenprepared and characterized in the solid state and in solution by P-31, Ga-71, and Tl-205 NMR. Biologicalstudies demonstrated the antitumor and antiviral activities of GaPd ( 12 ) P ( 8 ) and TlPd ( 12 ) P ( 8 ) being as efficient as cis-platinum against human melanoma and acute promyelocytic leukemiacells, exerting inhibitory activity against two herpetic viruses,HSV-2 and HCMV, in a dose-response manner. Three gallium(III)- and thallium(III)-containing polyoxopalladates(POPs) have been synthesized and structurally characterized in thesolid state and in solution, namely, the phosphate-capped 12-palladatenanocubes [XPd12O8(PO4)(8)](13-) (X = Ga-III, GaPd ( 12 ) P ( 8 ); X =Tl-III, TlPd ( 12 ) P ( 8 )) and the 23-palladate double-cube[Tl-2 (Pd23P14O70)-Pd-III(OH)(2)](20-) (Tl ( 2 ) Pd ( 23 ) P ( 14 )). The cuboid POPs, GaPd ( 12 ) P ( 8 ) and TlPd ( 12 ) P ( 8 ), are solution stable as verified by the respective P-31, Ga-71, and Tl-205 nuclear magnetic resonance(NMR) spectra. Of prime interest, the spin-spin coupling schemesallowed for an intimate study of the solution behavior of the Tl-III-containing POPs via a combination of P-31 and Tl-205 NMR, including the stoichiometry of the major fragmentsof Tl ( 2 ) Pd ( 23 ) P ( 14 ). Moreover,biological studies demonstrated the antitumor and antiviral activityof GaPd ( 12 ) P ( 8 ) and TlPd ( 12 ) P ( 8 ), which were validated to be asefficient as cis-platinum against human melanomaand acute promyelocytic leukemia cells. Furthermore, GaPd ( 12 ) P ( 8 ) and TlPd ( 12 ) P ( 8 ) exerted inhibitory activity against two herpeticviruses, HSV-2 and HCMV, in a dose-response manner.