Reductive Quenching of the Ruthenium(ii) Trisbipyridyl Excited State by Ruthenocene Analogs: Partitioning Between Energy and Electron Transfer.
Azam S.Ahmed
Faculty Advisor: M. G. Hill

     Reductive quenchers are not very common and even more rare are reductive quenchers that do not interfere with experiments that involve the absorption of light with 500-800 nm wavelengths. Three quenchers that meet these criteria are CpRuHB(pz)3, CpRuHB(3,5-dMpz)3, and Cp*RuHB(pz)3. After Ru(Il)(bpy)32+ is excited, there are only two ways for the electron to repopulate the HOMO: by photon emission or radiative decay. However, in the presence of a reductive quencher, it is possible for the excited electron to repopulate the HOMO by two additional pathways: electron transfer or energy transfer. Since the two Cyclopentadienyl compounds have similar oxidation potentials, their rates of electron transfer quenching should be comparable, but the rates of energy transfer quenching should differ. However, when comparing CpRuHB(pz)3 and Cp*RuHB(pz)3 the major difference in their ability to quench should be electron transfer.