Highly emissive 4-carbazole-appended salen-indium complex: the effect of strong donor-acceptor interaction

초록

Herein, we report our findings on 4-carbazole (CBZ)-appended salen-based indium complexes, CBZIn1 and CBZIn2, which feature diimine bridges exhibiting different electron-accepting properties. Notably, CBZIn2 exhibited a significantly higher photoluminescence quantum efficiency (PLQY, & phi;PL) in toluene than CBZIn1, with a value over 15 times greater (& phi;PL = 57.7% for CBZIn2; & phi;PL = 3.7% for CBZIn1). In particular, in the rigid state of THF at 77 K, CBZIn2 exhibited a near-unity PLQY of 98.2%. Even in the PMMA film, CBZIn2 maintained a high level of PLQY (& phi;PL = 70.2%). These results can be attributed to the highly efficient radiative decay process based on intramolecular charge-transfer (ICT) transition between the moderately twisted CBZ, characterized by its conformational rigidity and the 1,2-dicyanoethylene-bridged salen, which exhibits a strong electron-accepting ability. Furthermore, these findings are supported by theoretical calculations. The paper presents a highly photoluminescent 4-CBZ-appended indium-based complex in THF at 77 K (& phi;PL = 98.2%) and PMMA film (& phi;PL = 70.2%). These results were obtained by the formation of an efficient D-A interaction.

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