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Self‐Complementary [2]Catenanes and Their Related [3]Catenanes
Author(s) -
Cabezon Beatriz,
Cao Jianguo,
Raymo Françisco M.,
Stoddart J. Fraser,
White Andrew J. P.,
Williams David J.
Publication year - 2000
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20000616)6:12<2262::aid-chem2262>3.0.co;2-g
Subject(s) - catenane , supramolecular chemistry , cyclophane , chemistry , crystallography , stereochemistry , molecule , organic chemistry , crystal structure
Three [3]catenanes with cavities large enough to accommodate aromatic guests have been designed and synthesized (yields=5–20 %) by means of kinetically controlled self‐assembly processes. The X‐ray structural analysis of one of three [3]catenanes confirmed the presence of a rectangular cavity (dimensions=7×11 Å) lined by π‐electron‐rich recognition sites and hydrogen‐bond acceptor groups. In spite of their apparently ideal recognition features, none of these [3]catenanes bind guests incorporating a π‐electron‐deficient bipyridinium unit. However, the template‐directed syntheses of the [3]catenanes also produce, in yields of 2–23 %, [2]catenanes incorporating a 1,5‐dioxynaphtho[38]crown‐10 interlocked with a bipyridinium‐based tetracationic cyclophane. The X‐ray structural analyses of two of these [2]catenanes revealed that a combination of [π⋅⋅⋅π] and [C−H⋅⋅⋅π] interactions is responsible for the formation of supramolecular homodimers in the solid state. 1 H NMR spectroscopic investigations of the four [2]catenanes demonstrated that supramolecular homodimers are also formed ( K a =17–31 M −1 , T =185 K) in (CD 3 ) 2 CO solutions. Dynamic 1 H NMR spectroscopy revealed that the 1,5‐dioxynaphtho[38]crown‐10 and tetracationic cyclophane components in the four [2]catenanes and in the three [3]catenanes circumrotate (Δ G c ≠ =9‐14 kcal mol −1 ) through each other's cavity in (CD 3 ) 2 CO. Similarly, the 1,5‐dioxynaphthalene and the bipyridinium ring systems rotate (Δ G c ≠ =10‐14 kcal mol −1 ) about their [O⋅⋅⋅O] and [N⋅⋅⋅N] axes, respectively, in solution.