Self-Assembled Monolayers of Single-Molecule Magnets [Tb{Pc′(SR)8}2] on Gold

Authors

  • Dr. Ulrich Glebe,

    1. Institute of Chemistry, University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel (Germany)
    2. Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel (Germany)
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  • Prof. Tobias Weidner,

    1. National ESCA and Surface Analysis Center for Biomedical Problems (NESAC/BIO)Departments of Bioengineering and Chemical Engineering, University of Washington, Seattle, Washington 98195 (USA)
    2. Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany)
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  • Dr. Joe E. Baio,

    1. National ESCA and Surface Analysis Center for Biomedical Problems (NESAC/BIO)Departments of Bioengineering and Chemical Engineering, University of Washington, Seattle, Washington 98195 (USA)
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  • Dr. Denise Schach,

    1. Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany)
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  • Dr. Clemens Bruhn,

    1. Institute of Chemistry, University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel (Germany)
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  • Dr. Axel Buchholz,

    1. Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstrasse 8, 07743 Jena (Germany)
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  • Prof. Winfried Plass,

    1. Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstrasse 8, 07743 Jena (Germany)
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  • Dr. Stephan Walleck,

    1. Chemistry Department, Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld (Germany)
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  • Prof. Thorsten Glaser,

    1. Chemistry Department, Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld (Germany)
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  • Prof. Ulrich Siemeling

    Corresponding author
    1. Institute of Chemistry, University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel (Germany)
    2. Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel (Germany)
    • Institute of Chemistry, University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel (Germany)
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Abstract

The magnetic properties of the bis(phthalocyaninato)terbium complexes [Tb{Pc′(SR)8}2] (1) containing eight β-positioned long-chain alkylthio substituents SR (a: R=n-C8H17, b: R=n-C12H25) were studied by SQUID measurements, which revealed that both compounds are single-molecule magnets with an effective energy barrier for spin reversal significantly higher than that found for pristine bis(phthalocyaninato)terbium [Tb(Pc)2]. Thin films on gold were fabricated from 1 a and 1 b by chemisorption from solution and were characterised by near-edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS). In the case of 1 a, atomic force microscopy (AFM) was used in addition. The results are in accord with the formation of self-assembled monolayers which contain the macrocyclic rings mainly in an approximately horizontal orientation. The chemisorption is primarily due to the peripheral SR substituents, giving rise to coordinatively bound thioether units, whose alkyl chains are in an almost parallel orientation with respect to the surface. In the case of 1 b, covalently attached thiolate units were also observed, indicating that the chemisorption process can lead to carbon–sulfur bond cleavage. In addition, the crystal structure of 1 a was determined.

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