Controlling emission energy, self-quenching, and excimer formation in highly luminescent N--C--N-coordinated platinum(II) complexes.

A series of cyclometalated platinum(II) complexes have been prepared, [PtL(n)Cl], containing N--C--N-coordinating, terdentate ligands based on 1,3-dipyridylbenzene (HL(1)), incorporating aryl substituents at the central 5 position of the ligand. All of the new complexes are intensely luminescent in a degassed solution at 298 K (phi = 0.46-0.65 in CH(2)Cl(2)) with lifetimes in the microsecond range (7.9-20.5 micros). The introduction of the aryl substituents leads to a red shift in the lowest-energy, intense charge-transfer absorption band compared to [PtL(1)Cl] (401 nm in CH(2)Cl(2)), in the order H 100 nm. The X-ray structures of the biphenylyl- and methyl-substituted complexes are reported, together with those of the 2-pyridyl- and mesityl-substituted ligands and the key synthetic intermediate 1-bromo-3,5-di(2-pyridyl)benzene