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Room‐Temperature Long‐Lived 3 IL Excited State of Rhodamine in an N N Pt II Bis(acetylide) Complex with Intense Visible‐Light Absorption
Author(s) -
Huang Ling,
Zeng Le,
Guo Huimin,
Wu Wanhua,
Wu Wenting,
Ji Shaomin,
Zhao Jianzhang
Publication year - 2011
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201100777
Subject(s) - chemistry , excited state , acetylide , photochemistry , triplet state , ultrafast laser spectroscopy , quantum yield , photon upconversion , chromophore , fluorescence , spectroscopy , atomic physics , ion , physics , organic chemistry , quantum mechanics
An N N Pt II bis(acetylide) complex was prepared with the rhodamine fluorophore [Pt–Rho, in which N N is dbbpy = 4,4′‐bis( tert ‐butyl‐2,2′‐bipyridine)]. Complex Pt–Rho shows intense absorption in the visible region ( ϵ = 185800 M –1 cm –1 at 556 nm) and a fluorescence emission of the ligand ( λ em = 580 nm, Φ L = 41.1 %, τ L = 2.50 ns). The long‐lived rhodamine‐localised intraligand triplet excited state ( 3 IL, τ T = 83.0 μs) was proposed to be populated upon excitation of the rhodamine ligand, proved by nanosecond time‐resolved transient absorption and spin density analysis; the triplet excited state was studied by time‐dependent DFT calculations. In comparison, the model complex (dbbpy)Pt II bis(phenylacetylide) (Pt–Ph) shows weak absorption in the visible region ( ϵ = 14700 M –1 cm –1 at 424 nm) and a short‐lived metal‐to‐ligand charge‐transfer excited state ( 3 MLCT) ( τ T = 1.36 μs). Complex Pt–Rho was used as triplet sensitiser for upconversion based on triplet–triplet annihilation. An upconversion quantum yield of 11.2 % was observed. Our strategy to access the long‐lived 3 IL excited state of the organic chromophore by metallation with Pt II will be useful for the preparation of transition metal complexes that show intense absorption of visible light and long‐lived triplet excited states.