Luminescence tuning of organoboron quinolates through substituent variation at the 5-position of the quinolato moiety

A series of organoboron quinolates with emission colors ranging from blue to red have been prepared. In comparison to the respective AlQ(3) derivatives a distinct blue-shift of the emission is observed. Theoretical calculations serve to provide insight into the nature of the frontier orbitals and the effect of the substituents in the 5-position of the quinolate ligands on the relative HOMO and LUMO energy levels. An efficient new blue emitting material with a pinacolborane substituent has been identified.