1. Multiple Catenanes Derived from Calix[4]arenes
by Leyong Wang, Myroslav O. Vysotsky, Anca Bogdan, Michael Bolte, and Volker Böhmer
Science
Volume 304(5675):
May 28, 2004
Published by AAAS

2. Fig. 1. (A) Hydrogen-bonded dimer of a tetraurea calix[4]arene 1 or 2, showing the mutual orientation of the urea residues R. Ether groups are omitted for clarity.
(A) Hydrogen-bonded dimer of a tetraurea calix[4]arene 1 or 2, showing the mutual orientation of the urea residues R. Ether groups are omitted for clarity. (B) Schematic representation of the synthesis of multicatenanes 5 and 6 by metathesis reaction of selectively formed heterodimers 1·4 and 2a·4 followed by hydrogenation (reactions a and b). While reaction d led to a complicated mixture of products, reaction c (which has not yet been checked) seems at least an alternative to a, although wrong connections between double bonds are possible for c in contrast to a.
Leyong Wang et al. Science 2004;304:
Published by AAAS

3. Scheme 1. Formula survey. Formula survey.
Leyong Wang et al. Science 2004;304:
Published by AAAS

4. Fig. 2. 1H NMR spectra (400 MHz) of (A) homodimer 2a2 (chloroform-d1); (B) ill-defined assemblies of 4; (C) heterodimer 2a·4; (D) [8]catenane 6 (all in dichloromethane-d2); (E) 6 (in THF-d8); (F to H) 6 (in pyridine-d5) at 25°C, 55°C and 100°C, respectively.
1H NMR spectra (400 MHz) of (A) homodimer 2a2 (chloroform-d1); (B) ill-defined assemblies of 4; (C) heterodimer 2a·4; (D) [8]catenane 6 (all in dichloromethane-d2); (E) 6 (in THF-d8); (F to H) 6 (in pyridine-d5) at 25°C, 55°C and 100°C, respectively. Signals of the urea groups (α and β for the hydrogens of NH groups nonattached and attached to the calixarene moieties, respectively), signals of the calixarene aromatic hydrogens (γ, γ′), and signals of the methylene bridge protons ArCH2Ar (δ, δ′) are indicated; signals of solvents are marked with asterisks.
Leyong Wang et al. Science 2004;304:
Published by AAAS

5. Fig. 3. Space-filling representation of the molecular structure of 6 in the crystalline state.
Space-filling representation of the molecular structure of 6 in the crystalline state. (Left) Top view. Methoxy groups of one calix[4]arene are pointing toward the reader. (Right) Side view. The two multimacrocyclic calix[4]arenes are colored blue and red. Hydrogen atoms are omitted for clarity.
Leyong Wang et al. Science 2004;304:
Published by AAAS