Room 304, Chemistry Building
Professor Claudia Turro
Ohio State University
Excited state processes of transition metal complexes initiated by the absorption of light have potential applications in various fields, such as photochemotherapy (PCT) and solar energy conversion. These reactions include photoinduced ligand exchange, charge transfer, photoisomerization, and energy transfer to produce 1O2. In the case of Ru(II) and Rh2(II,II) complexes, the relative energies of the metal-to-ligand charge transfer (MLCT), ligand-field (LF, metal-centered), and ligand-centered (LC) excited states play a key role in the observed reactivity.
The use of light to activate the action of a drug has become an important mode of cancer therapy, in some cases superior to traditional treatments, due to its low levels of invasiveness and systemic toxicity. Photoinduced ligand exchange, which can be used to release caged drugs or to induce covalent DNA binding with spatiotemporal control, together with the sensitization of 1O2, represent important reactions initiated by light with potential applications in photochemotherapy (PCT). These photoinduced reactions of Ru(II) complexes will be presented, along with their activity towards biological targets and cancer cells. Importantly, Ru(II) complexes were recently discovered to undergo multiple photochemical pathways following activation with light, and this property was used to design new dual-action compounds. These new complexes are able to both release a medically relevant compound and to produce 1O2 and were shown to exhibit significant enhancement of activity stemming from their ability to induce cell death via two different, independent pathways. The ability of Rh2(II,II) complexes to localize in the mitochondria and induce apoptosis upon irradiation is also being explored. New strategies developed for the photoinduced exchange of pyridine-containing drugs and their attachment to tumor-targeting antibodies will be presented. These new complexes provide a new platform for drug delivery and enhanced therapeutic activity upon excitation with low energy light.