Login / Signup

Fluorene-decorated Ir(III) complexes: synthesis, photophysics and tunable triplet excited state properties in aggregation.

Senqiang ZhuQianqian PanYu-Hao LiWenqing LiuHongjun ZhuHongjun Zhu
Published in: Dalton transactions (Cambridge, England : 2003) (2022)
Two new heteroleptic cationic Ir(III) complexes bearing benzothiazole and pyridine motifs on fluorene groups were synthesized and characterized. Complexes Ir1 and Ir2 exhibit 1 π,π* transitions below 430 nm, with broad but weak metal-to-ligand and ligand-to-ligand charge transfer absorption bands above 430 nm. Both complexes possess long-lived emissions ( τ em = 0.37 μ s for Ir1, τ em = 5.41 μ s for Ir2) and triplet excited states ( τ TA = 0.14 μ s for Ir1, τ TA = 6.06 μ s for Ir2). Their optical properties in solution and aggregated states were also investigated. Both Ir(III) complexes exhibit aggregation-induced phosphorescence emission behavior in an acetonitrile-water mixture. As the water content increased to 90%, the emission intensities of complexes Ir1 and Ir2 increased nearly 3 times and 2.8 times, respectively. Moreover, nonlinear transmittance experiments were performed in CH 3 CN and a CH 3 CN-H 2 O mixture ( f w = 90%), and the strength of the reverse saturable absorption (RSA) at 532 nm followed the trend: Ir2 (CH 3 CN) ≥ Ir1 (CH 3 CN) > Ir2 (CH 3 CN-H 2 O) > Ir1 (CH 3 CN-H 2 O). Abundant triplet state excitons participated in the radiative transition progress, which inhibited the RSA process. These results indicate that the fluorene-decorated Ir(III) complexes are suitable for aggregation emission and optical power limiting applications.
Keyphrases
  • room temperature
  • lymph node metastasis
  • quantum dots
  • mass spectrometry
  • highly efficient