Optical and Redox Properties of Ruthenium Phthalocyanine Complexes Tuned with Axial Ligand Substituents

The optical and electrochemical properties of the ruthenium phthalocyanine complexes [[(t-Bu)4Pc]Ru(4-Rpy)2], where R = NO2, Me, NH2, and NMe2, are reported. The electron density at the macrocycle may be adjusted using the axial ligand substituents, which have varying electron-donating/withdrawing strengths. Electrochemical data show that the axial pyridine ligand substituents exert significant influence over the phthalocyanine ring-based redox processes. The axial ligands also influence the electronic absorption properties of the complexes with influence also being observed in the electrogenerated oxidized and reduced species.