Determination of the relative ligand-binding strengths in heteroleptic IrIII complexes by ESI-Q-TOF tandem mass spectrometry

Authors

  • Esra Altuntaş,

    1. Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich-Schiller-University Jena, Jena, Germany
    2. Jena Center for Soft Matter (JCSM), Jena, Germany
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  • Andreas Winter,

    1. Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich-Schiller-University Jena, Jena, Germany
    2. Jena Center for Soft Matter (JCSM), Jena, Germany
    3. Dutch Polymer Institute (DPI), AX, Eindhoven, The Netherlands
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  • Anja Baumgaertel,

    1. Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich-Schiller-University Jena, Jena, Germany
    2. Jena Center for Soft Matter (JCSM), Jena, Germany
    3. Dutch Polymer Institute (DPI), AX, Eindhoven, The Netherlands
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  • Renzo M. Paulus,

    1. Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich-Schiller-University Jena, Jena, Germany
    2. Jena Center for Soft Matter (JCSM), Jena, Germany
    3. Dutch Polymer Institute (DPI), AX, Eindhoven, The Netherlands
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  • Christoph Ulbricht,

    1. MEET, University of Münster, Münster, Germany
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  • Anna C. Crecelius,

    1. Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich-Schiller-University Jena, Jena, Germany
    2. Jena Center for Soft Matter (JCSM), Jena, Germany
    3. Dutch Polymer Institute (DPI), AX, Eindhoven, The Netherlands
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  • Nikolaus Risch,

    1. Faculty of Science, Paderborn University, Paderborn, Germany
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  • Ulrich S. Schubert

    Corresponding author
    1. Jena Center for Soft Matter (JCSM), Jena, Germany
    2. Dutch Polymer Institute (DPI), AX, Eindhoven, The Netherlands
    • Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich-Schiller-University Jena, Jena, Germany
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Ulrich S. Schubert, Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstr. 10, 07743 Jena, Germany. E-mail: ulrich.schubert@uni-jena.de

Abstract

An electrospray ionization quadrupole time-of-flight mass spectrometer has been utilized to investigate the relative ligand-binding strengths in a series of heteroleptic-charged iridium(III) complexes of the general formula [(C^N)2IrIII(S-tpy)](PF6) by using variable collision energies. Collision-induced dissociation experiments were performed in order to study the stability of the IrIII complexes that are, for instance, suitable phosphors in light-emitting electrochemical cells. The ratio of signal intensities belonging to the fragment and the undissociated complex depends on the collision energy applied for the tandem mass spectra (MS/MS) analysis. By defining the threshold collision energy and the point of complete complex dissociation, it is possible to estimate the relative complex stabilities depending on the nature of the coordinated ligands [i.e. type of cyclometalating ligand (C^N), substituents on the S-shaped terpyridine (S-tpy)]. The collision energy values differed as a function of the coordination sphere of the IrIII centers. Copyright © 2011 John Wiley & Sons, Ltd.

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