Metal hybridization and electronic structure of Tris(8-hydroxyquinolato)aluminum (Alq3)

The metal-organic complex Tris(8-hydroxyquinolato)aluminum (Alq3) has been studied by energy and light polarization dependent photoemission. Resonant photoemission was used to identify the molecular orbitals involved in metal chelation. When adsorbed on cobalt and gold surfaces, marked differences in the Alq3 metal-to-ligand bonds were observed. The results indicate intramolecular aluminum-to-ligand bonding through the oxygen heteroatom when Alq3 is adsorbed on gold, but through the nitrogen heteroatom when on cobalt. These results indicate that substrate interfacial complex formation plays an important role in the Alq3 molecular configuration and intramolecular bonding.