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Calix[4]pyrroles containing deep cavities and fixed walls. Synthesis, structural studies and anion binding properties of the isomeric products derived from the condensation of p-hydroxyacetophenone and pyrrole.

Calix[4]pyrroles containing deep cavities and fixed walls. Synthesis, structural studies and anion binding properties of the isomeric products derived from the condensation of p-hydroxyacetophenone and pyrrole.
Calix[4]pyrroles containing deep cavities and fixed walls. Synthesis, structural studies and anion binding properties of the isomeric products derived from the condensation of p-hydroxyacetophenone and pyrrole.
The acid-catalyzed condensation of 4-hydroxyphenylmethyl ketone (p-hydroxyacetophenone) with pyrrole affords a new type of calix[4]pyrrole derivative that contains deep cavities and fixed walls. These new systems, which can be readily converted into the corresponding 4-methoxyphenyl species, can exist in the form of four different configurational isomers, as well as in different conformational forms. Three of the configurational isomers, namely the ????, ????, and ???? isomers, where the terms “?” and “?” indicate whether the bulky functionalized phenyl substituent faces “up” or “down” relative to the mean calixpyrrole plane, were isolated by column chromatography. Proof of structure and assignment of configuration was then effected using X-ray diffraction analysis. The affect of the meso-aryl substituent on the anion binding affinity of the receptor was investigated in solution (acetonitrile-d3:D2O; 99.5:0.5 v./v.) using standard 1H NMR titration techniques. Surprisingly, it was found that both the 4-hydroxyphenyl- and 4-methoxyphenyl-derived systems show lower affinities for small anions, viz. Cl-, and H2PO4-, than do simple unsubstituted calix[4]pyrroles such as meso-octamethylcalixpyrrole. On the other hand, increased selectivities and other binding effects ascribable to the ‘walls’ of the cavities were observed.
anion recognition, calixpyrrole, calixarene
0002-7863
11020-11021
Anzenbacher Jr., Pavel
c594b0ff-9e7a-4487-8053-dee3f45dcb92
Jursíková, Karolina
057682b3-1a88-405d-90f9-da2a58696bdc
Lynch, Vincent M.
1ca6d39d-b02d-4141-ab55-f566f00a09b5
Gale, Philip A.
ce0aa62f-d081-408b-8b00-6d954058afab
Sessler, Jonathan L.
d793ea76-a3a2-4ce1-a8d5-aca7d3307fbe
Anzenbacher Jr., Pavel
c594b0ff-9e7a-4487-8053-dee3f45dcb92
Jursíková, Karolina
057682b3-1a88-405d-90f9-da2a58696bdc
Lynch, Vincent M.
1ca6d39d-b02d-4141-ab55-f566f00a09b5
Gale, Philip A.
ce0aa62f-d081-408b-8b00-6d954058afab
Sessler, Jonathan L.
d793ea76-a3a2-4ce1-a8d5-aca7d3307fbe

Anzenbacher Jr., Pavel, Jursíková, Karolina, Lynch, Vincent M., Gale, Philip A. and Sessler, Jonathan L. (1999) Calix[4]pyrroles containing deep cavities and fixed walls. Synthesis, structural studies and anion binding properties of the isomeric products derived from the condensation of p-hydroxyacetophenone and pyrrole. Journal of the American Chemical Society, 121 (47), 11020-11021. (doi:10.1021/ja993195n).

Record type: Article

Abstract

The acid-catalyzed condensation of 4-hydroxyphenylmethyl ketone (p-hydroxyacetophenone) with pyrrole affords a new type of calix[4]pyrrole derivative that contains deep cavities and fixed walls. These new systems, which can be readily converted into the corresponding 4-methoxyphenyl species, can exist in the form of four different configurational isomers, as well as in different conformational forms. Three of the configurational isomers, namely the ????, ????, and ???? isomers, where the terms “?” and “?” indicate whether the bulky functionalized phenyl substituent faces “up” or “down” relative to the mean calixpyrrole plane, were isolated by column chromatography. Proof of structure and assignment of configuration was then effected using X-ray diffraction analysis. The affect of the meso-aryl substituent on the anion binding affinity of the receptor was investigated in solution (acetonitrile-d3:D2O; 99.5:0.5 v./v.) using standard 1H NMR titration techniques. Surprisingly, it was found that both the 4-hydroxyphenyl- and 4-methoxyphenyl-derived systems show lower affinities for small anions, viz. Cl-, and H2PO4-, than do simple unsubstituted calix[4]pyrroles such as meso-octamethylcalixpyrrole. On the other hand, increased selectivities and other binding effects ascribable to the ‘walls’ of the cavities were observed.

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More information

Published date: 1999
Keywords: anion recognition, calixpyrrole, calixarene

Identifiers

Local EPrints ID: 13959
URI: http://eprints.soton.ac.uk/id/eprint/13959
ISSN: 0002-7863
PURE UUID: 9e6c2a4e-d0db-4604-b1bc-9bb2f228955a

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Date deposited: 21 Dec 2004
Last modified: 15 Jul 2019 19:33

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Contributors

Author: Pavel Anzenbacher Jr.
Author: Karolina Jursíková
Author: Vincent M. Lynch
Author: Philip A. Gale
Author: Jonathan L. Sessler

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