Novel triphenylamine-based cyclometalated platinum(II) complexes for efficient luminescent oxygen sensing

Novel triphenylamine-based cyclometalated Pt(II) complexes containing a pyridyl moiety have been synthesized and fully characterized. The cyclometalating ligands were prepared via an efficient palladium-catalyzed ligand-free Suzuki reaction of 4-(diphenylamino)phenylboronic acid with 2-pyridyl bromides under aerobic and aqueous conditions. The photophysical properties of the complexes exhibited that introducing an electron-withdrawing group like trifluoromethyl or cyano group on the 5-position of the pyridine ring affected the LUMO level of the Pt(II)) complex significantly, resulting in a marked decrease in energy gap. Moreover, the complex with a cyano group at the 5-position imparts a substantial red-shift up to 56 nm. The O-2 sensitivity of the complexes was quantitatively evaluated in a polymer film. The results of the O-2-sensing sensitivity of the Pt(II) complexes demonstrated that the complex with a nitrile ligand exhibited the highest sensitivity (K-SV(app) = 0.102 Torr(-1)). The triphenylamine-based cyclometalated Pt(II) complexes are potential candidates for efficient luminescent oxygen sensing. (C) 2013 Elsevier Ltd. All rights reserved.