Tuning the Emission Lifetime in Bis-cyclometalated Iridium(III) Complexes Bearing Iminopyrene Ligands

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• 作者：Ashlee J. Howarth ; David L. Davies ; Francesco Lelj ; Michael O. Wolf ; Brian O. Patrick
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：November 17, 2014
• 年：2014
• 卷：53
• 期：22
• 页码：11882-11889
• 全文大小：480K
• ISSN：1520-510X

文摘

Bis-cyclometalated Ir(III) complexes with the general formula Ir(ppz)₂(X^NPyrene), where ppz = 1-phenylpyrazole and X^NPyrene is a bidentate chelate with X = N or O, are reported. Modifications on the ancillary ligand containing pyrene drastically affect the emission lifetimes observed (0.329 to 104 渭s). Extended emission lifetimes in these complexes compared to model complexes result from reversible electronic energy transfer or the observation of dual emission containing along-lived pyrene ligand-centered triplet (³LC) component. A combination of steady-state and time-resolved spectroscopic techniques are used to observe reversible electronic energy transfer in solution between the iridium core and pyrene moiety in the complex [Ir(ppz)₂(N_Me^NCH₂Pyr)][PF₆] (2), where N_Me^NCH₂Pyr = N-(pyren-1-ylmethyl)-1-(pyridin-2-yl)ethaneimine. Studies on [Ir(ppz)₂(N_Me^NCH₂Pyr)][PF₆] in a poly(methyl methacrylate) (PMMA) film reveal that reversible energy transfer is no longer effective, and instead, dual emission with a long-lived ³LC component from pyrene is observed. Dual emission is observed in additional cyclometalated iridium complexes bearing pyrene-containing ancillary ligands N^NPyrene and O^NPyrene when the complexes are dispersed in a PMMA film.