p-tert-Butylcalix[8]arene: An Extremely Versatile Platform for Cluster Formation

Authors

  • Stephanie M. Taylor,

    1. EastCHEM School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ (UK), Fax: (+44) 0131-650-6453
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  • Dr. Sergio Sanz,

    1. EastCHEM School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ (UK), Fax: (+44) 0131-650-6453
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  • Dr. Ruaraidh D. McIntosh,

    1. Institute of Chemical Sciences, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS (UK), Fax: (+44) 0131-451-3180
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  • Dr. Christine M. Beavers,

    1. Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 6R2100, Berkeley, California 94720 (USA)
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  • Dr. Simon J. Teat,

    1. Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 6R2100, Berkeley, California 94720 (USA)
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  • Prof. Euan K. Brechin,

    Corresponding author
    1. EastCHEM School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ (UK), Fax: (+44) 0131-650-6453
    • EastCHEM School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ (UK), Fax: (+44) 0131-650-6453
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  • Dr. Scott J. Dalgarno

    Corresponding author
    1. Institute of Chemical Sciences, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS (UK), Fax: (+44) 0131-451-3180
    • Institute of Chemical Sciences, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS (UK), Fax: (+44) 0131-451-3180
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Abstract

p-tert-Butylcalix[4]arene is a bowl-shaped molecule capable of forming a range of polynuclear metal clusters under different experimental conditions. p-tert-Butylcalix[8]arene (TBC[8]) is a significantly more flexible analogue that has previously been shown to form mono- and binuclear lanthanide (Ln) metal complexes. The latter (cluster) motif is commonly observed and involves the calixarene adopting a near double-cone conformation, features of which suggested that it may be exploited as a type of assembly node in the formation of larger polynuclear lanthanide clusters. Variation in the experimental conditions employed for this system provides access to Ln1, Ln2, Ln4, Ln5, Ln6, Ln7 and Ln8 complexes, with all polymetallic clusters containing the common binuclear lanthanide fragment. Closer inspection of the structures of the polymetallic clusters reveals that all but one (Ln8) are in fact based on metal octahedra or the building blocks of octahedra, with the identity and size of the final product dependent upon the basicity of the solution and the deprotonation level of the TBC[8] ligand. This demonstrates both the versatility of the ligand towards incorporation of additional metal centres, and the associated implications for tailoring the magnetic properties of the resulting assemblies in which lanthanide centres may be interchanged.

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