Novel Heteroleptic Ruthenium(II) Complexes with 2,2a?2- Bipyridines Containing a Series of Electron-Donor and Electron-Acceptor Substituents in 4,4a?2-Positions: Syntheses, Characterization, and Application as Sensitizers for ZnO Nanowire-Based Solar Cells

摘要： A novel series of complexes of the formula [Ru(4,4′-X2-bpy)2(Mebpy-CN)](PF6)2 (X = ?CH3, ?OCH3, ?N(CH3)2; Mebpy-CN = 4-methyl-2,2′-bipyridine-4′-carbonitrile) have been synthesized and characterized by spectroscopic, electrochemical, and photophysical techniques. Inclusion of the electron-withdrawing substituent ?CN at one bpy ligand and di?erent electron-donor groups ?X at the 4,4′-positions of the other two bpy ligands produce a ?ne tuning of physicochemical properties. Redox potentials, electronic absorption maxima, and emission maxima correlate well with Hammett’s σ p parameters of X. Quantum mechanical calculations are consistent with experimental data. All the complexes can be anchored through the nitrile moiety of Mebpy-CN over ZnO nanowires in dye-sensitized solar cells that exhibit an improvement of light to electrical energy conversion e?ciency as the electronic asymmetry increases in the series.