Blue-Phosphorescent Pt(II) Complexes of Tetradentate Pyridyl–Carbolinyl Ligands: Synthesis, Structure, Photophysics, and Electroluminescence
Feiling Yu, Yongjian Sheng, Dandan Wu, Ke Qin, Hongbo Li, Guohua Xie, Qin Xue, Zhengyi Sun, Zhenzhong Lu, Huili Ma, Xiao‐Chun Hang
Abstract
Blue phosphorescent tetradentate pyridyl–carbolinyl Pt(II) complexes, Pt(ppzOclpy-Me), Pt(ppzOclpy-iPr), and Pt(ppzOclpy-mesi), were purposefully synthesized and investigated with their photophysical and luminescent properties. The complexes, incorporating with carbolinyl moieties, have twisted planar structure. X-ray crystallography revealed that the intraligand N···H–C hydrogen bond reversely turned the twisty pyridyl moiety back into the chelating plane. Computational analyses confirmed that the metal-to-ligand charge-transfer transition character appears in the singlet manifolds. However, the ligand-centered transitions rule in their triplet states, which accounts for the phosphorescent emission. The Pt(II) complexes emit blue light with peak wavelengths (λmax) of 461–481 nm and moderate photoluminescent quantum yields (Φ = 34–46% in dichloromethane and Φ = 44–52% in films). The electroluminescent devices were fabricated by solution processes, giving blue emissions peaking at around 470 nm.