Electrochemiluminescence of Heteroleptic Iridium(III) Complexes Featuring Substituted 2,4‐diphenylpyridinato Ligands
- 1Centre For Sustainable Bioproducts Faculty of Science, Engineering and Built Environment Deakin University Waurn Ponds Victoria Australia
- 2School of Chemistry University of Melbourne Parkville Victoria Australia
Abstract
Five heteroleptic iridium(III) complexes bearing cyclometalated 2,4‐diphenylpyridinato ligands and a 4,4′‐dimethyl‐2,2′‐bipyridine ancillary ligand were synthesized. Modulation of substituents at the 4′‐position of the cyclometalated phenyl ring provided systematic variation in oxidation potentials, emission wavelengths, and luminescence quantum yields, used herein to interrogate the relationship between electronic structure and electrochemiluminescence (ECL) response. With tri‐n‐propylamine as co‐reactant, the relative ECL intensities of the complexes depended strongly on the excitation pathway, for which distinct optima in co‐reactant concentration were also identified. The complexes bearing more electron‐withdrawing substituents exhibited the greatest ECL intensities via the reductive excitation (direct) pathway, but rendered the oxidative excitation (indirect) pathway energetically inaccessible. Under cathodic potentials with benzoyl peroxide as co‐reactant, the unsubstituted complex exhibited the highest ECL intensities within the series, exceeding those of [Ru(bpy)3]2+ under selected conditions. These findings highlight that ECL performance is governed by luminescence efficiency, the excitation pathway and energetic alignment with the co‐reactant system, and that even subtle changes in luminophore properties can have multiple, sometimes competing, effects on ECL intensity.
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BibTeX
@article{jayawardana2026electrochemiluminescence,
title = {{Electrochemiluminescence of Heteroleptic Iridium(III) Complexes Featuring Substituted 2,4‐diphenylpyridinato Ligands}},
author = {Ovini Jayawardana and El M. S. Martin and Oliver G. Stansfield and Egan H. Doeven and Carol Hua and Timothy U. Connell and Paul S. Francis},
journal = {Chemistry (Weinheim an Der Bergstrasse, Germany)},
year = {2026},
month = aug,
doi = {10.1002/chem.71519},
url = {https://doi.org/10.1002/chem.71519},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Electrochemiluminescence of Heteroleptic Iridium(III) Complexes Featuring Substituted 2,4‐diphenylpyridinato Ligands
AU - Ovini Jayawardana
AU - El M. S. Martin
AU - Oliver G. Stansfield
AU - Egan H. Doeven
AU - Carol Hua
AU - Timothy U. Connell
AU - Paul S. Francis
PY - 2026
DA - 2026/08/03
JO - Chemistry (Weinheim an Der Bergstrasse, Germany)
DO - 10.1002/chem.71519
UR - https://doi.org/10.1002/chem.71519
AB - Five heteroleptic iridium(III) complexes bearing cyclometalated 2,4‐diphenylpyridinato ligands and a 4,4′‐dimethyl‐2,2′‐bipyridine ancillary ligand were synthesized. Modulation of substituents at the 4′‐position of the cyclometalated phenyl ring provided systematic variation in oxidation potentials, emission wavelengths, and luminescence quantum yields, used herein to interrogate the relationship between electronic structure and electrochemiluminescence (ECL) response. With tri‐n‐propylamine as co‐reactant, the relative ECL intensities of the complexes depended strongly on the excitation pathway, for which distinct optima in co‐reactant concentration were also identified. The complexes bearing more electron‐withdrawing substituents exhibited the greatest ECL intensities via the reductive excitation (direct) pathway, but rendered the oxidative excitation (indirect) pathway energetically inaccessible. Under cathodic potentials with benzoyl peroxide as co‐reactant, the unsubstituted complex exhibited the highest ECL intensities within the series, exceeding those of [Ru(bpy)3]2+ under selected conditions. These findings highlight that ECL performance is governed by luminescence efficiency, the excitation pathway and energetic alignment with the co‐reactant system, and that even subtle changes in luminophore properties can have multiple, sometimes competing, effects on ECL intensity.
SN - 0947-6539
SN - 1521-3765
ER -