Macrocyclic ligands interlocked

Two interlocked macrocyclic ligands as in (15) are topologically related to the catenanes, whence the name catenand derives.34,186 187 These macrocycles complex a variety of metals, presumably in a tetrahedral geometry.34,186 The stabilizing effect of the catenand topology is evident in the observed redox stability of the nickel(I) complex186 as well as the reluctance toward demetallation, observed for the copper(I) complexes.187... 

These complexes of catenands are remarkably stable. However, treatment of the complex with cyanide results in demetallation and the formation of the free catenane, in which the two macrocyclic ligands are still interlocked. There is a conformational change upon demetallation and in the solid state the rings have slipped . It is not trivial to estab-... 

Cesario, M., Dietrich-Buchecker, C.O., Gui Them, J., Pascard, C. and Sauvage, J.P. 1985. Molecular structure of a catenand and its copper (I) catenate complete rearrangement of the interlocked macrocyclic ligands by complexation, J. Chem. Soc. Chem. Commun., 244-247. 

Catenands (17) are interlocked macrocyclic ligands, which complex a variety of metal ions. ... 

Dietrich-Buchecker. C.O. Sauvage. J.-P. Kern, J.M. Synthesis and electrochemical studies of catenates Stabilization of low oxidation states by interlocked macrocyclic ligands. 3. Am. Chern. Soc. 1989. 111. 7791-7800. 

Stabilization of Low Iron Oxidation State by Interlocked Macrocyclic Ligands... 

The use of interlocked polyether-diimine macrocycle ligand (Fig. 5) has interesting implications for the coordination of metal ions, especially those of iron [32]. 

Dietrich-Buchecker, C.O. Sauvage, J.P., and Weiss, J. (1986) Interlocked macrocyclic ligands A catenand whose rotation of one ring into the other is precluded by bulky substituents. Tetrahedron Lett. 27, 2257-2260. Amabilino, D.B. and Stoddart, J.F. (1993) New approach to controlling catenated structures, Rec. Trav. Chim. Pays Bos 112, 1534-1544. 

Dietrich-Buchecker, C. and Sauvage, J.P. (1990) Templated synthesis of interlocked macrocyclic ligands, the catenands. Preparation and characterization of the prototypical bis-30 membered ring system. Tetrahedron, 46,503-512. 

Hydrophobic forces are also important in the assemblies of metallo-supramolecular catenanes. One of the most interesting examples is formed when one of the unpolar bipyridine ligands of one macrocycle is included spontaneously in the other macrocycle s internal cavity [39]. Here, the benzene unit of the one macrocycle serves as a guest molecule for the other macrocycle, and the cyclization is favored by n-n interactions. In addition, the minimization of hydrophobic surfaces in polar medium constitutes the second driving force for the catenane formation. The quantitative formation of the [2]catenanes 31a and 31b based on this principle are depicted in Figure 13. Formation of catenane 31b was found to be reversible. Even at room temperature, two monomeric ring structures equilibrate quickly due to the labile nature of Pd-N bond and interlocked molecular ring system 31b is formed. 

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