Origin of the Aggregation-Induced Phosphorescence of Platinum(II) Complexes: The Role of Metal-Metal Interactions on Emission Decay in the Crystalline State

Discerning the origins of the phosphorescent aggregation-induced emission (AIE) from Pt(II) complexes is crucial for developing the broader range of photo-functional materials. Over the past few decades, several mechanisms of phosphorescent AIE have been proposed, however, not have been directly elucidated. Herein, we describe phosphorescence and deactivation processes of four class of AIE active Pt(II) complexes in the crystalline state based on experimental and theoretical investigation. These complexes show metal-to-ligand and/or metal-metal-to-ligand charge transfer emission in crystalline state with different heat resistance against thermal emission quenching. The calculated energy profiles including the minimum energy crossing point between S-0 and T-1 states were consistent with the heat resistant properties, which provided the mechanism for AIE expression. Furthermore, we have clarified the role of metal-metal interaction in AIE by comparing two computational models.

Automated summary

In this study, the phosphorescence and deactivation processes of four classes of AIE active Pt(II) complexes in the crystalline state were described based on experimental and theoretical investigation. The role of metal-metal interaction in AIE and the mechanism of heat resistance against thermal emission quenching were clarified. The calculated energy profiles provided insights into the AIE expression.