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

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posted on 2019-01-01, 00:00 authored by L Chen, David HayneDavid Hayne, Egan DoevenEgan Doeven, J Agugiaro, D J D Wilson, Luke HendersonLuke Henderson, Tim ConnellTim Connell, Ryan Nai, Richard AlexanderRichard Alexander, S Carrara, C F Hogan, P S Donnelly, Paul FrancisPaul Francis
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.

History

Journal

Chemical science

Volume

10

Issue

37

Pagination

8654 - 8667

Publisher

Royal Society of Chemistry

Location

Cambridge, Eng.

ISSN

2041-6520

eISSN

2041-6539

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2019, The Royal Society of Chemistry