Issue 37, 2019

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

Abstract

Translation of the highly promising electrogenerated chemiluminescence (ECL) properties of Ir(III) complexes (with tri-n-propylamine (TPrA) as a co-reactant) into a new generation of ECL labels for ligand binding assays necessitates the introduction of functionality suitable for bioconjugation. Modification of the ligands, however, can affect not only the photophysical and electrochemical properties of the complex, but also the reaction pathways available to generate light. Through a combined theoretical and experimental study, we reveal the limitations of conventional approaches to the design of electrochemiluminophores and introduce a new class of ECL label, [Ir(C^N)2(pt-TOxT-Sq)]+ (where C^N is a range of possible cyclometalating ligands, and pt-TOxT-Sq is a pyridyltriazole ligand with trioxatridecane chain and squarate amide ethyl ester), which outperformed commercial Ir(III) complex labels in two commonly used assay formats. Predicted limits on the redox potentials and emission wavelengths of Ir(III) complexes capable of generating ECL via the dominant pathway applicable in microbead supported ECL assays were experimentally verified by measuring the ECL intensities of the parent luminophores at different applied potentials, and comparing the ECL responses for the corresponding labels under assay conditions. This study provides a framework to tailor ECL labels for specific assay conditions and a fundamental understanding of the ECL pathways that will underpin exploration of new luminophores and co-reactants.

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

Supplementary files

Article information

Article type
Edge Article
Submitted
21 mar 2019
Accepted
26 jul 2019
First published
31 jul 2019
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2019,10, 8654-8667

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

L. Chen, D. J. Hayne, E. H. Doeven, J. Agugiaro, D. J. D. Wilson, L. C. Henderson, T. U. Connell, Y. H. Nai, R. Alexander, S. Carrara, C. F. Hogan, P. S. Donnelly and P. S. Francis, Chem. Sci., 2019, 10, 8654 DOI: 10.1039/C9SC01391A

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