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Structure, Stability and Guest Affinity of Tris(3‐ureidobenzyl)amine Capsules in Solution
Author(s) -
Alajarín Mateo,
Pastor Aurelia,
Orenes RaúlAngel,
MartínezViviente Eloísa,
Rüegger Heinz,
Pregosin Paul S.
Publication year - 2007
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/chem.200601022
Subject(s) - chemistry , tris , toluene , amine gas treating , nuclear magnetic resonance spectroscopy , magnetization transfer , crystallography , stereochemistry , organic chemistry , biochemistry , medicine , magnetic resonance imaging , radiology
In non‐competitive solvents, the tris(3‐ureidobenzyl)amines 1 a – c form dimeric assemblies in which guests such as CH 3 CN, CH 3 NO 2 , CH 2 Cl 2 , CH 3 I, CH 2 BrCl, CH 2 Br 2 , CHCl 3 and C 6 H 6 can be encapsulated. Variable temperature 1 H and 1 H, 1 H‐ROESY NMR spectroscopy, as well as pulsed‐gradient spin‐echo (PGSE) diffusion measurements were used to investigate the encapsulation within 1 a⋅1 a ( 1 a : tris{3‐[ N ′‐(4‐butylphenyl)ureido]benzyl}amine). Kinetic parameters for the encapsulation of CH 3 NO 2 , CH 2 Cl 2 and CH 3 I, both in CDCl 3 and in [D 8 ]toluene have been obtained by using magnetisation transfer methods. These data are discussed together with the thermodynamic parameters. The affinity between guest and capsule seems to be dictated mainly by the electronic, size and shape complementarity between cavity and guest. A gating mechanism for guest exchange is proposed.