Synthesis of trinuclear Pd–Ru–Pd porphyrin complexes with axially ligated Pd centers. Prominent metal-to-ligand charge transfer band in the visible region

• Synthesis of di- and trinuclear porphyrin complex with axially ligated ligands.
• MLCT property changes upon introduction of metal units to the ligands.
• In the trinuclear Pd–Ru–Pd complex, metal(Ru) to axially ligated ligands takes place.

Ru–porphyrin complexes with pyridylpyrazine as metal coordination sites were synthesized. Introduction of Pd-alkyl units to the binding site led to the formation of a novel Pd–Ru–Pd trinuclear complex. The metalation causes drastic changes in the electrochemical and photophysical properties. The trinuclear complex exhibited a prominent metal-to-axial ligand charge transfer band in the visible region due to small energy gap between the Ru-based HOMO and the axial ligand-based LUMO. These changes resulted in the drastic color change from orange to green.

Ru–porphyrin complexes with pyridylpyrazine as metal coordination sites were synthesized and the introduction of Pd-alkyl units led to the formation of a novel Pd–Ru–Pd trinuclear complex. The trinuclear complex exhibited a prominent MLCT band because of the directional change in the MLCT processes showing a distinct color change from orange to dark-green.Figure optionsDownload as PowerPoint slide