Tetradentate Platinum(II) Complex with a 6/5/7 Metallocycle

Tetradentate Pt(II) complexes are promising phosphorescent materials for photocatalysts and solar cells, especially as robust emitters and sensitizers in organic light-emitting diodes (OLEDs). In this work, we report a tetradentate Pt(II) complex, PtZL7, which utilizes a conjugately linked ligand of a phenylquinoline/benzimidazole/phenoxy anion to form a novel 6/5/7 metallocycle. To the best of our knowledge, PtZL7 is a rare example of a tetradentate Pt(II) complex containing a fused 6/5/7 metallocycle. The molecular geometry and photophysical and excited-state properties of PtZL7 were systematically investigated through experimental and theoretical studies. PtZL7 has a highly distorted molecular geometry and limits intermolecular interactions. The PtZL7 exhibited red region emission with peak wavelengths at 617 and 607 nm and fwhm values of 125 and 115 nm at room temperature (RT) in toluene and poly(methyl methacrylate) (PMMA) film, respectively, and a high quantum efficiency of 62% in PMMA film. According to time-dependent density functional theory (TD-DFT) and NTO analyses, there is a mixed 3MLCT and 3ILCT transition in the T1 state of PtZL7 at RT, which is responsible for broader spectra.