Subject Number : S-16-MS-0029
Support Type : Collaborative research
Proposal Title (English) : Structural, Electronic and Photophysical Properties of Photoinduced Electron Transfer in Ruthenium-Viologen Complexes: A Theoretical Investigation
Username (English) : Malinee Promkatkaew
Affiliation (English) : Faculty of Science at Sriracha, Kasetsart University Sriracha Campus, Thailand

1. Summary
Theoretical investigations were utilized to investigate the structural and electronic properties of three diruthenium and viologen complexes including 1) [Ru-V-Ru], 2) [Ru-V-RuCOOH], and 3) [Ru-V-V-Ru]. We have been used the hybrid density B3LYP functional for understanding the ground state properties for diruthenium and viologen complexes and parent complexes: Ru(bpy)32+ and MV2+. Excited singlet states have been examined by the time-dependent DFT (TD-DFT) with CAM-B3LYP methods. Theoretical findings have been compared between oxidation states and experimental spectra. As the results, the correlation between the calculated UV-Vis transition and molecular orbitals for the excited state clearly established that the ruthenium retains its formal Ru(bpy)32+ oxidation state whereas viologen changes theirs the reductive product (V2+) into the radical cation (V+) and neutral (V0). The photoinduced electron transfer for each complex was examined using the details of the computational results for both the absorption spectra and the redox properties.
2. Experimental
Ground state geometries and their redox states were investigated for Ruthenium [Ru(bpy)3], methylviologen (MV) and three diruthenium and viologen complexes consisting of 1) [Ru-V-Ru], 2) [Ru-V-RuCOOH], and 3) [Ru-V-V-Ru]. All structures were fully optimized using the density functional theory (DFT) with B3LYP functional and cc-pVDZ basis set for the H, C, N and O atoms and the Los Alamos effective core potential (ECP) including relativistic effects plus double -£ atomic orbitals for the heavier Ru atom. The LANL2DZ basis set was employed. To determine the energies and character of the singlet excited state geometries, time-dependent DFT (TD-DFT) with the CAM-B3LYP functional method was performed based on ground state optimization of the structures. The solvent effects in all studied complexes were simulated using the conductor-like polarizable continuum (CPCM) model. Acetonitrile (CH3CN) was chosen as a reference solvent for consistency with the experimental studies. All calculations were carried out using the Gaussian 09 suite of programs version B.01.
3. Results and Discussion

Figure: Comparison of the calculated (columns) and experimental (lines) absorption spectra before 0 min ( ), 10 min ( ) and 20 min ( ) irradiation of complex 1) [Ru-V-Ru].
4. Others
N/A
5. Publication/Presentation
M. Promkatkaew, S. Suramitr, T. Karpkird, M. Ehara and S. Hannongbua, The 15th International Congress of Quantum Chemistry (ICQC) (8-13 June 2015), Beijing, China
6. Patent
N/A