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

• The TPA-based cyclometalating ligands were prepared efficiently via a Pd-catalyzed ligand-free and aerobic Suzuki reaction.
• Structure–photoelectric properties of the novel TPA-based cyclometalated Pt(II) complexes are established.
• The complex with a cyano group at the 5-position demonstrated the highest sensitivity toward the 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 O2 sensitivity of the complexes was quantitatively evaluated in a polymer film. The results of the O2-sensing sensitivity of the Pt(II) complexes demonstrated that the complex with a nitrile ligand exhibited the highest sensitivity (KSVapp = 0.102 Torr−1). The triphenylamine-based cyclometalated Pt(II) complexes are potential candidates for efficient luminescent oxygen sensing.

A series of novel triphenylamine-based cyclometalated Pt(II) complexes have been synthesized and fully characterized. The results of the O2-sensing sensitivity of the Pt(II) complexes demonstrated that the complex with a nitrile ligand exhibited the highest sensitivity. The present result is the first example of a nitrile compound as a cyclometalating ligand for efficient O2 sensing.Figure optionsDownload as PowerPoint slide