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Dimeric Capsules by the Self‐Assembly of Triureidocalix[6]arenes through Hydrogen Bonds
Author(s) -
González Juan J.,
Ferdani Riccardo,
Albertini Emanuela,
Blasco José M.,
Arduini Arturo,
Pochini Andrea,
Prados Pilar,
de Mendoza Javier
Publication year - 1999
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/(sici)1521-3765(20000103)6:1<73::aid-chem73>3.0.co;2-#
Subject(s) - hydrogen bond , self assembly , calixarene , polymer chemistry , chemistry , polymer science , materials science , organic chemistry , molecule
A number of calix[6]arenes bearing ureas at the upper rim positions of alternate rings 1, 3 and 5 were prepared and studied in detail by NMR spectroscopy and gel permeation chromatography. N ‐Unsubstituted ureas were shown to dimerize through a cyclic array of hydrogen bonds to give cylindrical cavities capable of encapsulating small molecules such as dichloromethane, benzene and fluorobenzene. Slow equilibria between dimer and monomer were observed in [D 6 ]DMSO‐CDCl 3 mixtures. By contrast, N ‐substituted ureas are monomeric. All urea monomers with bulky O ‐substituents display a solvent‐dependent, slow equilibrium between C 3v and C s cone conformations.