Absorption and photoluminescence properties of 4-substituted Alq3 derivatives and tris-(4-hydroxypyridinoanthrene)aluminum

A series of 4-substituted Alq₃ derivatives have been synthesized. Photophysical properties of the complexes in solution have been studied in detail. The results show that Hammett σ_p constants of the substituents have a linear correlation with the emission maximum values of the aluminum complexes. Substitution at the 4-position improves the color purity of the emission and it has also a strong influence on the quantum yields. A new type of Alq₃ derivative, tris-(4-hydroxypyridinoanthrene)aluminum, has a good quantum yield and high emission color purity.