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

TitleTuning the Emission Lifetime in Bis-cyclometalated Iridium(III) Complexes Bearing Iminopyrene Ligands
Publication TypeJournal Article
Year of Publication2014
AuthorsHowarth, AJ, Davies, DL, Lelj, F, Wolf, MO, Patrick, BO
JournalINORGANIC CHEMISTRY
Volume53
Pagination11882-11889
Date PublishedNOV 17
ISSN0020-1669
Abstract

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 mu 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 ((LC)-L-3) 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<\^{}>NCH(2)Pyr)]{[}PF6] (2), where N-Me<\^{}>NCH(2)Pyr = 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 (LC)-L-3 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.

DOI10.1021/ic501032t