Factors that influence singlet oxygen formation vs. ligand substitution for light-activated ruthenium anticancer compounds

This review focuses on light-activated ruthenium anticancer compounds and the factors that influence which pathway is favored. Photodynamic therapy (PDT) is favored by p expansion and the presence of low-lying triplet excited states (e.g. (MLCT)-M-3, (IL)-I-3). Photoactivated chemotherapy (PACT) refers to light-driven ligand dissociation to give a toxic metal complex or a toxic ligand upon photo substitution. This process is driven by steric bulk near the metal center and weak metal-ligand bonds to create a low-energy 3MC state with antibonding character. With protic dihydroxybipyridine ligands, ligand charge can play a key role in these processes, with a more electron-rich deprotonated ligand favoring PDT and an electron-poor protonated ligand favoring PACT in several cases.

Automated summary

This review discusses light-activated ruthenium anticancer compounds and the factors that influence the preferred pathway. Photodynamic therapy (PDT) and photoactivated chemotherapy (PACT) are two main light-activated treatment methods, which depend on the electronic properties of ligands and the characteristics of metal complexes.