Near-Infrared Electrochemiluminescence from Bistridentate Ruthenium(II) Di(quinoline-8-yl)pyridine Complexes in Aqueous Media

Mayoorini Majuran, Georgina Armendariz-Vidales, Serena Carrara, Mohammad A. Haghighatbin, Leone Spiccia, Peter J. Barnard, Glen B. Deacon, Conor F. Hogan, Kellie L. Tuck

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We report the synthesis, photophysics, electrochemistry and electrochemiluminescence (ECL) of two dqp (dqp=2,6-di(quinoline-8-yl)pyridine) based ruthenium(II) complexes, bearing either a n-butyl ester (1) or the corresponding carboxylic acid functionality (2). The complexes were prepared from [Ru(dqp)(MeCN)3][PF6]2 by reaction with the dqp precursor using microwave irradiation. In both cases, photoluminescence spectra present strong 3MLCT-based red/near-infrared (NIR) emissions centred at about 710 nm. The photoluminescence quantum yields were 6.1 % and 1.8 % for 1 and 2 respectively while the excited state lifetimes were 3.60 μs and 2.37 μs. Both complexes are ECL active, although ECL efficiency (ΦECL) of 1 was substantially higher than 2, due to its more favourable electrochemical properties. Importantly, 1 also gave strong ECL in aqueous media, which is rare for near-infrared emitters. The results suggest the possibility of very interesting ECL sensing applications for this class of emitter in biological media.

Original languageEnglish
Pages (from-to)346-352
Number of pages7
Issue number2
Publication statusPublished - Feb 2020


  • bistridendate ligands
  • electrochemiluminescence
  • near-infrared emission
  • photoluminescence
  • ruthenium(II)

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