Synthesis, Characterization, and Optoelectronic Properties of Iridium Complexes Bearing Nonconjugated Six-Membered Chelating Ligands - Université de Rennes Access content directly
Journal Articles Inorganic Chemistry Year : 2018

Synthesis, Characterization, and Optoelectronic Properties of Iridium Complexes Bearing Nonconjugated Six-Membered Chelating Ligands

Abstract

We report the synthesis, characterization, and optoelectronic properties of a series of four new luminescent iridium(III) complexes, 1-4, of the form [Ir(CN)(NN)]PF (where CN is the nonconjugated benzylpyridinato (bnpy) and NN is a neutral diimine ancillary ligand) with the goal of investigating the effect of the methylene spacer between the coordination moieties of the CN ligand on the optoelectronic properties of the complexes. The crystal structures of 1-3 illustrate two possible orientations of the methylene unit of the bnpy ligand. The formation of these two separate conformers is a result of the conformational flexibility of the bnpy ligand. In complexes 3 and 4, mixtures of the two conformers were observed by H NMR spectroscopy in CDCl at room temperature, whereas only a single conformer is detected for 1 and 2. Detailed DFT calculations corroborate NMR experiments, accounting for the presence and relative populations of the two conformers. The optoelectronic properties of all four complexes, rationalized by the theoretical study, demonstrate that the interruption of conjugation in the CN ligands results in a reduced electrochemical gap but similar triplet state energies and lower photoluminescence quantum yields in comparison to the reference complexes R1-R4. Depending on the nature of the NN ligand, we observe (1) marked variations of the ratio of the conformers at ambient temperature and (2) phosphorescence ranging from yellow to red.
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Dates and versions

hal-01737373 , version 1 (25-05-2018)

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Claus Hierlinger, Amlan K. Pal, Filippo Stella, Tomas Lebl, David B. Cordes, et al.. Synthesis, Characterization, and Optoelectronic Properties of Iridium Complexes Bearing Nonconjugated Six-Membered Chelating Ligands. Inorganic Chemistry, 2018, 57 (4), pp.2023-2034. ⟨10.1021/acs.inorgchem.7b02940⟩. ⟨hal-01737373⟩
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