Synthesis, characterization, photophysical, and redox properties of three trinuclear Ru(II) polypyridyl complexes possessing 5-amino-1,10-phenanthroline ligands

Three ruthenium(II) polypyridyl complexes with 5-amino-1,10-phenanthroline ligands have been successfully designed and synthesized. They have been fully characterized by ESI-MS, ESI-HRMS, 1 H NMR, and elemental analyses. The photophysical and electrochemical properties of the three complexes have been investigated in organic solvent. The geometrical configuration and the electron density distribution in the frontier molecular orbitals of the three complexes have been studied. The three complexes show metal-to-ligand charge transfer ( 1 MLCT) absorption at 445 nm, and intense triplet metal-to-ligand ( 3 MLCT) emission at around 619 nm in fluid solution at 298 K and 580 nm in low-temperature glass. Electrochemical studies of the three complexes are consistent with one Ru III/II reversible couple at around 1.31 V accompanied by three ligand-centered reduction couples.