Controlling the energetics and lifetimes of excited states in unconventional chromophores: ligand-to-metal (LMCT) and metal-to-metal (MMCT) charge transfer

Seminar | February 17 | 4-5 p.m. |  Pitzer Auditorium, 120 Latimer Hall

 Prof. Walter Weare, Department of Chemistry, North Carolina State University

 College of Chemistry

The discovery of new chromophores, particularly those synthesized from earth abundant elements, is critical for artificial photosynthesis to become a reality. The talk will address our work on unconventional chromophores based on LMCT and MMCT. We have identified an extremely long-lived LMCT excited state (1.6 ms at room temperature in methanol) and believe that this is a "symmetry trapped" excited state. The synthesis and photochemistry of new unsupported mu-oxido bridged heterobimetallic systems (Ti-O-M) composed entirely of earth-abundant elements will also be discussed. These molecules are being used to probe aspects of metal-to-metal charge transfer (MMCT) photochemistry. By varying the donor identity (M=Cr, Mn, Fe), magnetic coupling and spin state is controlled in both the ground and excited states. We have demonstrated that that intersystem crossing or spin-crossover (high spin -> low spin) can be tools for lengthening the lifetimes of such MMCT excited states.

 Light refreshments will be served at 3:50pm in The Coffee Lab, 510-643-0572