Open Access Dissertation
Date of Award
The 3MLCT excited states generated from tris-bipyridineruthenium(II), [Ru(bpy)3]2+ and related complexes was ionized by 405 nm irradiation in ambient, acidic aqueous solutions. The photoionization product was Ru(bpy)3]3+ and an electron with a quantum yield of about 0.040.02 in 0.5 M acid. However, 532 nm radiation does not induce photoionization, and it generates the 3MLCT excited state that can be photoionized by 405 nm irradiation. The proton is a very good electron scavenger, and the rate of phoionization of the 3MLCT excited state was determined to be acid dependent and it increased about ten-fold for acid concentrations beween 0.001 and 4 M when 0.1 M isopropanol was used to scavenge hydrogen atoms. Dramatic decreases in [Ru(bpy)3]2+ emission intensities were observed when dual laser irradiations were used for 10-30 min in 0.5 M H+. The minimum free energy required to ionize the [Ru(bpy)3]2+ 3MLCT excited state is about 2 eV (620 nm). Such thermodynamic considerations also indicate that photoionization processes are possible for many of the electron donors whose excited states might be considered for use as photosensitizers. This suggests that the shorter wavelength visible light could lead to their degradation through reactions of the resulting free radicals and other product species when they are used in long term applications
Alnaed, Marim Khalifa, "Chemical And Physical Studies Of Charge Transfer Excited States Of Ruthenium Complexes With Aromatic Ligands" (2018). Wayne State University Dissertations. 2001.