Self-assembly of dimeric tetraurea calix[4]pyrrole capsules

Ballester, Pablo and Gil-Rami­rez, Guzman (2009) Self-assembly of dimeric tetraurea calix[4]pyrrole capsules. Proceedings of the National Academy of Sciences, 106 (26). pp. 10455-10459. ISSN 0027-8424

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Calix[4]pyrroles having extended aromatic cavities have been functionalized with 4 ureas in the para position of their meso phenyl substituents. This elaboration of the upper rim was completed in 2 synthetic steps starting from the α,α,α,α-tetranitro isomer of the calix[4]pyrrole obtained in the acid catalyzed condensation of p-nitrophenyl methyl ketone and pyrrole. In dichloromethane solution and in the presence of 4,4′-bipyridine N-N′-dioxide the tetraurea calix[4]pyrrole dimerizes reversibly forming a cyclic array of 16 hydrogen bonds and encapsulating 1 molecule of bis-N-oxide. The encapsulated guest is bound in the cavity by hydrogen bonding to the 2 endohedral calix[4]pyrrole centers. Further evidence for dimerization of the tetraurea calix[4]pyrroles is provided by 1H-NMR experiments and by the formation of mixed capsules.

Keywords:1 (4 nitrophenyl)ethanone, 4,4' bipyridine n n' dioxide, bipyridine derivative, dichloromethane, dimer, heterodimer, nitrobenzene derivative, oxide, phenyl group, pyrrole, pyrrole derivative, tetraurea calix4pyrrole derivative, unclassified drug, urea derivative, calix(4)pyrrole, calixarene, ketone, porphyrin, urea, article, chemical structure, conformation, crystallization, dimerization, encapsulation, hydrogen bond, hydrogenation, polymerization, priority journal, proton nuclear magnetic resonance, synthesis, chemistry, nuclear magnetic resonance spectroscopy, thermodynamics, X ray diffraction, Calixarenes, Hydrogen Bonding, Ketones, Magnetic Resonance Spectroscopy, Models, Molecular, Molecular Conformation, Molecular Structure, Oxides, Porphyrins, Pyrroles, Urea, X-Ray Diffraction
Subjects:F Physical Sciences > F100 Chemistry
Divisions:College of Science > School of Chemistry
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ID Code:22488
Deposited On:11 Mar 2016 11:56

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