Synthesis and characterization of 2,6-di(quinolin-8-yl)pyridines. New ligands for bistridentate Ru(II) complexes with microsecond luminescent lifetimes.

The synthesis of 4-substituted and 4-aryl-substituted 2,6-di(quinolin-8-yl)pyridines is described. The tridentate ligands were prepared via a palladium-catalyzed Suzuki-Miyaura cross-coupling reaction or via a one-step ring-forming reaction generating the central pyridine ring. X-ray crystal structures and 1H NMR shifts are discussed and compared to the corresponding data for a RuII bistridentate complex. Intramolecular stacking of two quinoline units in the RuII complex is suggested by 1H NMR data and also observed in the X-ray structure.