Quantum Dot Photoactivation of Pt(IV) Anticancer Agents: Evidence of an Electron Transfer Mechanism Driven by Electronic Coupling

Herein we elucidate the mechanism of photoreduction of the Pt(IV) complex cis,cis,trans-[Pt(NH3)2(Cl)2(O2CCH2CH2CO2H)2] (1) into Pt(II) species (among which is cisplatin) by quantum dots (QDs), a process which holds potential for photodynamic therapy. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) methodologies, integrated by selected experiments, were employed to study the interaction and the light-induced electron transfer (ET) process occurring between two QD models and 1. Direct adsorption of the complex on the nanomaterial surface results in large electronic coupling between the LUMO (lowest unoccupied molecular orbital) of the excited QD* and the LUMO+1 of 1, providing the driving force to the light-induced release of the succinate ligands from the Pt derivative. As confirmed by photolysis experiments performed a posteriori, DFT highlights that QD photoactivation of 1 can favor the formation of preferred Pt(II) photoproducts, paving the way for the design of novel hybrid Pt(IV)–semiconductor systems where photochemical processes can be finely tuned.