TRANSITION-METALS AS ASSEMBLING AND TEMPLATING SPECIES - FROM CATENANES AND KNOTS TO STRINGS THREADED THROUGH MOLECULAR RINGS

New dicopper(I) knots have been synthesized as well as their face-to-f ace isomers. The knots range from 80 to 90-membered rings and their pr eparation yields depend crucially on structural parameters such as num ber of methylene fragments linking the two chelating units and length of the polyethyleneoxy unit used in the cyclization reaction. The best yield was obtained for an 84-membered knotted ring with a -(CH2)6- co nnector : this relatively long fragment allows pronounced winding of t he double helix precursor and is thus favorable to the knotting reacti on. The face-to-face complexes were in some instances the major produc ts, being obtained in yields amounting to 24% in the case of the dicop per (I) bis 43-membered ring system. Based on a related three-dimensio nal template effect, other multicomponent molecular systems have been synthesized. They contain rings, coordinating open-chain fragments and transition metals and can be constructed at will by taking advantage of the strong preference of copper(I) for bis- chelate complexes. The compounds consist of one or two rings threaded by the acyclic subunit, the various organic components being assembled via coordination to co pper(I).