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Co‐Reactant and Annihilation Electrogenerated Chemiluminescence of [Ir(df‐ppy) 2 (ptb)] + Derivatives
Author(s) -
Soulsby Lachlan C.,
Agugiaro Johnny,
Wilson David J. D.,
Hayne David J.,
Doeven Egan H.,
Chen Lifen,
Pham Tien T.,
Connell Timothy U.,
Driscoll Aaron J.,
Henderson Luke C.,
Francis Paul S.
Publication year - 2020
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.202000001
Subject(s) - luminophore , polypyrrole , chemistry , photochemistry , excited state , chemiluminescence , iridium , electrochemistry , luminescence , materials science , catalysis , organic chemistry , electrode , physics , optoelectronics , nuclear physics
The [Ir(df‐ppy) 2 (ptb)] + complex (where df‐ppy=2‐(2,4‐difluorophenyl)pyridine anion; ptb=1‐benzyl‐1,2,3‐triazol‐4‐ylpyridine) has previously been shown to be a promising blue luminophore for electrogenerated chemiluminescence (ECL). Herein, we examine the ECL of three [Ir(df‐ppy) 2 (ptb)] + derivatives (containing df(CF 3 )‐ppy‐Me, df(CN)‐ppy, or df‐ppy‐CF 3 ligands) in comparison with the parent complex. In the annihilation mode, all four complexes exhibited ECL, although the emission from [Ir(df(CN)‐ppy) 2 (ptb)] + was weak and red‐shifted from its photoluminescence. The absence of this shift in the corresponding reductive‐oxidation co‐reactant ECL with benzoyl peroxide (BPO), and the very low ECL intensity in oxidative–reductive co‐reactant ECL with tri‐ n ‐propylamine (TPrA) enables this effect to be ascribed to oxidative degradation. The [Ir(df‐ppy‐CF 3 ) 2 (ptb)] + complex gave the greatest ECL intensities of the four [Ir ( C ∧ N ) 2 (ptb)] + complexes in the annihilation mode and through both co‐reactant pathways, and shows great potential as a blue electrochemiluminophore. In “mixed annihilation” ECL experiments involving the oxidation of Ir(ppy) 3 and the reduction of the [Ir ( C ∧ N ) 2 (ptb)] + complexes, only [Ir(df‐ppy) 2 (ptb)] + and [Ir(df(CF 3 )‐ppy‐Me) 2 (ptb)] + elicited the green ECL from Ir(ppy) 3 *, as the electron‐withdrawing substituents on the other two complexes lower the SOMO energy of the reduced complexes below that required to attain the Ir(ppy) 3 * excited state upon reaction with [Ir(ppy) 3 ] + .