Synthesis of [5]Rotaxanes Containing Bi- and Tridentate Coordination Sites in the Axis

Authors

  • Dr. Jean-Paul Collin,

    Corresponding author
    1. Laboratoire de Chimie Organo-Minérale, Institut de Chimie, LC3 UMR 7177 du CNRS, Université de Strasbourg, 4 rue Blaise Pascal, 67070 Strasbourg Cedex (France), Fax: (+33) 368851368
    • Laboratoire de Chimie Organo-Minérale, Institut de Chimie, LC3 UMR 7177 du CNRS, Université de Strasbourg, 4 rue Blaise Pascal, 67070 Strasbourg Cedex (France), Fax: (+33) 368851368
    Search for more papers by this author
  • Dr. Stéphanie Durot,

    Corresponding author
    1. Laboratoire de Chimie Organo-Minérale, Institut de Chimie, LC3 UMR 7177 du CNRS, Université de Strasbourg, 4 rue Blaise Pascal, 67070 Strasbourg Cedex (France), Fax: (+33) 368851368
    • Laboratoire de Chimie Organo-Minérale, Institut de Chimie, LC3 UMR 7177 du CNRS, Université de Strasbourg, 4 rue Blaise Pascal, 67070 Strasbourg Cedex (France), Fax: (+33) 368851368
    Search for more papers by this author
  • Michel Keller,

    1. Laboratoire de Chimie Organo-Minérale, Institut de Chimie, LC3 UMR 7177 du CNRS, Université de Strasbourg, 4 rue Blaise Pascal, 67070 Strasbourg Cedex (France), Fax: (+33) 368851368
    Search for more papers by this author
  • Prof. Jean-Pierre Sauvage,

    Corresponding author
    1. Laboratoire de Chimie Organo-Minérale, Institut de Chimie, LC3 UMR 7177 du CNRS, Université de Strasbourg, 4 rue Blaise Pascal, 67070 Strasbourg Cedex (France), Fax: (+33) 368851368
    • Laboratoire de Chimie Organo-Minérale, Institut de Chimie, LC3 UMR 7177 du CNRS, Université de Strasbourg, 4 rue Blaise Pascal, 67070 Strasbourg Cedex (France), Fax: (+33) 368851368
    Search for more papers by this author
  • Dr. Yann Trolez,

    1. Laboratoire de Chimie Organo-Minérale, Institut de Chimie, LC3 UMR 7177 du CNRS, Université de Strasbourg, 4 rue Blaise Pascal, 67070 Strasbourg Cedex (France), Fax: (+33) 368851368
    Search for more papers by this author
  • Mario Cetina,

    1. Department of Chemistry, Nanoscience Center, University of Jyväskylä, P.O.Box 35, 40014 Jyväskylä (Finland)
    Search for more papers by this author
  • Prof. Kari Rissanen

    1. Department of Chemistry, Nanoscience Center, University of Jyväskylä, P.O.Box 35, 40014 Jyväskylä (Finland)
    Search for more papers by this author

Abstract

A new example of a linear [5]rotaxane has been synthesized by using the traditional “gathering-and-threading” approach but based on an unusual axle incorporating a symmetrical bis(bidentate) chelating fragment built on a 4,7-phenanthroline core. The stoppering reaction is particularly noteworthy since, instead of using a trivial bulky stopper as precursor to the blocking group, two semistoppered copper-complexed [2]pseudorotaxanes (namely [2]semirotaxanes) are used, which leads to the desired [5]rotaxane in good yield. The efficiency of the method relies on the use of “click” chemistry, with its very mild conditions, and on the protection by a transition-metal (copper(I)) of the various coordinating groups present in the fragments to be interconnected (terpy and bidentate chelating groups), thus inhibiting potential detrimental side reactions during the copper-catalyzed stoppering reaction. Since the external fragments and the central core of the system contain tri- and bidentate chelating units, respectively, the axle of the final [5]rotaxane incorporates two types of coordinating units: two external terpy groups (terpy: 2,2′:6′,2′′-terpyridine) and two central bidentate ligands. Such a situation enables the system to tidy two different metals centers, and to localize them in a priori well-defined positions. This is what was observed when mixing the free ligand with a mixture of Zn2+ and Li+: the zinc(II) ions were unambiguously shown to occupy the external sites, whereas the Li+ cations were found in the central part of the [5]rotaxane. An X-ray diffraction study carried out on a [3]pseudorotaxane, the axis of which is similar to the central part of the [5]rotaxane axle, demonstrates that Zn2+ is clearly five-coordinate, the fifth ligand being a counterion, even when the coordination site of the pseudorotaxane is designed for four-coordinate metals, which is in marked contrast with copper(I) or Li+.

Ancillary