4- vs. 5-phenylquinolinolate aluminum (III) isomers

A method for the synthesis of 4-arylquinolinolate ligand and their AlIII complexes based on Michael reaction of 2-methoxyaniline with 1-phenylpropenones was developed. The resulting 4-aryl-8-methoxyquinoline was demethylated and converted to corresponding AlIII complexes. Photophysical properties of two 4-aryl-Alq3 derivatives were then compared with properties of the parent Alq3 and a 5-phenyl-Alq3 congener. It appears that the 5-aryl derivatives show improved luminescence but also decreased physical stability. Electroluminescence of the prepared materials is presented and compared to Alq3 and a 5-phenyl-Alq3.