Electrochemiluminescence of Iridium Complexes

A conceptual framework for the development of iridium(iii) complex-based electrogenerated chemiluminescence labels

“…The ECL efficiency ( φ ECL ) of a luminophore is dependent on both its redox potentials and excited state character. In the case of heteroleptic Ir( iii ) complexes, these parameters can be readily tuned through minor modifications of ligand structure, to stabilise or destabilise the frontier molecular orbitals with some degree of selectivity 9,10,42. Early exploration of Ir(C^N) 2 (acac) complexes showed high ECL efficiencies with a wide range of emission colours, in reactions with radical anions of aromatic nitriles 43.…”

“…, Fig. 2a–c) have emerged as promising candidates for a new generation of ECL labels 2,9,10. Compared to the traditional Ru( ii ) polypyridine chelates, the Ir( iii ) complexes exhibit much greater quantum yields (offering enhanced analytical performance) and their emission wavelengths and electrochemical potentials can be readily manipulated through changes in ligand structure,11 creating exciting opportunities for multi-colour and/or potential-resolved multiplexed ECL systems 12–15.…”

Aggregation-Induced Emission in Electrochemiluminescence: Advances and Perspectives

“…For diagnostics and biomedical applications, the luminophore must also possess a good degree of solubility in aqueous media where biological analyses are usually performed. Keeping into account also the role of the spin statistics in the formation of the exciton [14], the use of phosphorescent emitters have been found to outperform fluorescent dyes, resulting in the field being dominated by transition metal complexes, in particular ruthenium and iridium complexes [15][16][17][18][19][20][21]. Unfortunately, phosphorescent compounds possess relatively low photoluminescence quantum yield (PLQY), especially in aerated conditions as elemental oxygen is an effective quencher of the long-lived excited triplet state.…”

Aggregation-Induced Emission in Electrochemiluminescence: Advances and Perspectives

“…For diagnostics and biomedical applications, the luminophore must also possess a good degree of solubility in aqueous media where biological analyses are usually performed. Keeping into account also the role of the spin statistics in the formation of the exciton [14], the use of phosphorescent emitters have been found to outperform fluorescent dyes, resulting in the field being dominated by transition metal complexes, in particular ruthenium and iridium complexes [15][16][17][18][19][20][21]. Unfortunately, phosphorescent compounds possess relatively low photoluminescence quantum yield (PLQY), especially in aerated conditions as elemental oxygen is an effective quencher of the long-lived excited triplet state.…”