Chemiluminescence and electrochemiluminescence of water-soluble iridium(III) complexes containing a tetraethylene-glycol functionalised triazolylpyridine ligand

Anal Chim Acta. 2024 May 22;1304:342470. doi: 10.1016/j.aca.2024.342470. Epub 2024 Mar 22.ABSTRACTBACKGROUND: Iridium(III) complexes, exhibiting high luminescence quantum yields and a wide range of emission colours, are promising alternatives to tris(2,2'-bipyridine)ruthenium(II) for chemiluminescence (CL) and electrochemiluminescence (ECL) detection. This emerging class of reagent, however, is limited by the poor solubility of many iridium(III) complexes in aqueous solution, and lack of understanding of their remarkably variable selectivities towards different analytes.RESULTS: Seven [Ir(C^N)2(pt-TEG)]+ complexes, exhibiting a wide range of reduction potentials and emission energies, were examined with six model analytes. For CL, cerium(IV) was used as the oxidant. The alkylamine analytes generally produced greater CL and ECL with the more readily oxidised Ir(III) complexes (C^N = piq, bt, ppy), predominantly through the 'direct' pathway requiring oxidation of both metal complex and analyte. Aniline derivatives that did not also contain secondary or tertiary alkylamines elicited CL from the less readily oxidised complexes (C^N = df-ppy-CF3, df-ppy) via energy transfer. The most difficult to oxidise complexes (C^N = df(CF3)-ppy-Me, df(CN)-ppy) gave poor responses due to the limited potential window of the solvent and inefficiency of energy transfer to their high energy excited states. Greater CL and/or ECL intensities were generally obtained for each analyte with at least one...

Source: Analytica Chimica Acta - April 18, 2024 Category: Chemistry Authors: Lifen Chen Kim Quayle Zoe M Smith Timothy U Connell Egan H Doeven David J Hayne Jacqui L Adcock David J D Wilson Johnny Agugiaro Michael L Pattuwage Natasha S Adamson Paul S Francis Source Type: research