Rigid biimidazole ancillary ligands as an avenue to bright deep blue cationic iridium(III) complexes
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Herein we report the synthesis and optoelectronic characterisation of three deep blue-emitting cationic iridium complexes, of the form [Ir(dFppy)2(N^N)]PF6, bearing biimidazole-type N^N ancillary ligands (dFppyH = 2-(2,4-difluorophenyl)pyridine). Complex 1 contains the parent biimidazole, biim, while 2 contains a dimethylated analog, dMebiim, and 3 contains an ortho-xylyl-tethered biimidzole, o-xylbiim. We explore a strategy of tethering the biimidazole in order to rigidify the complex and increase the photoluminescent quantum yield, culminating in deep blue (λmax: 457 nm in MeOH at 298 K) ligand-centered emission with a very high photoluminescent quantum yield of 68% and microsecond emission lifetime. Density functional theory calculations elucidate the origin of such disparate excited state kinetics across this series, especially in light of virtually identical optoelectronic properties observed for these compounds.
Henwood , A F , Evariste , S , Slawin , A M Z & Zysman-Colman , E 2014 , ' Rigid biimidazole ancillary ligands as an avenue to bright deep blue cationic iridium(III) complexes ' Faraday Discussions , vol 174 , pp. 165-182 . DOI: 10.1039/C4FD00107A
© Royal Society of Chemistry 2014. This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at http://dx.doi.org/10.1039/C4FD00107A. No further copies may be made or distributed.
EZ-C acknowledges the University of St Andrews for financial support. Date of Acceptance: 03/06/2014
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