1387631-06-2Relevant academic research and scientific papers
Room temperature long-lived triplet excited state of fluorescein in N^N Pt(II) bisacetylide complex and its applications for triplet-triplet annihilation based upconversions
Wu, Wenting,Zhao, Jianzhang,Wu, Wanhua,Chen, Yinghui
, p. 189 - 196 (2012/08/27)
The room temperature (RT) long-lived triplet excited state of fluorescein was observed in a dbbpy Pt(II) bisfluorescein acetylide complex (Pt-1, where dbbpy = 4,4′-di(tert-butyl)-2,2′-bipyridine). The complex shows strong absorption of visible light (ε = 24,600 M-1 cm -1 at 457 nm). Interestingly, the phosphorescence of the coordination centre is completely quenched and only the fluorescence of ligand was observed for Pt-1 at RT. At 77 K, a phosphorescence band at 667 nm was observed. Spin density analysis and nanosecond time-resolved transient difference absorption spectroscopy proved that the lowest-lying triplet excited state of the complex Pt-1 is localized on the fluorescein acetylide ligand (3IL state), for which the lifetime was determined as 16.4 μs (RT, by the time-resolved transient absorption spectra). The quenching of the 3MLCT phosphorescence in Pt-1 is due to the intramolecular energy transfer of 3MLCT → 3IL. The complex Pt-1 was used as the triplet sensitizer for the triplet-triplet annihilation (TTA) based upconversion. Our results will be useful for preparation of transition metal complexes that show intense absorption of visible light and long-lived triplet excited states, these photophysical properties are useful for applications in photovoltaics, photocatalysis or upconversions, etc.
