4 p.m. - 5:15 p.m. Location: SLC 1.102
Dr. Evgeny Danilov (North Carolina State University)
Photosensitization is a photophysical alteration occurring in one molecular entity as a result of initial absorption of light by another molecular entity. The latter is called a photosensitizer, the former is a reaction center. The term metal-organic was first introduced by Dr. Kirk Schanze at the University of Florida to emphasize the importance of distinguishing this class of molecules from organometallics which assume a presence of metal-carbon bonds. A result of photosensitization could be energy or charge transfer from the sensitizer that can trigger a chain of events such as successive energy transfer, catalytic reaction, polymerization, and so on. A good photosensitizer should be a good absorber of light over a broad spectral range, be capable to release or accept an electron upon photoexcitation, be chemically stable but also modifiable to tune its properties, and have a long (~microsecond) life time of the photoexcited state. The most known and much studied photosensitizer is Ru(bpy)32+ where bpy is 2,2’-bipyridine. However, Ru is among least abundant elements in Earth’s crust. Accordingly, a persistent challenge is to find sensitizers based on more abundant and cost efficient first-row metals. Promising results have been reported using Cu(I) diimine compounds strategically designed to have a long excited state life time. In this talk, I will discuss the results of time-resolved spectroscopic studies on sub-picosecond time scale that reveal photophysical properties of the Cu(I) compounds responsible for their life time. On a different note, I will talk about a project where the ultrafast time-resolved spectroscopy was used to study quenching of Ir(III) photosensitizer compounds by nitro aromatic molecules with potential applications in real-world chemical sensors.