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Proc Natl Acad Sci U S A. 2009 Jun 30;106(26):10449-54. doi: 10.1073/pnas.0811663106. Epub 2009 Feb 23.

Molecular recognition and self-assembly special feature: Multipoint molecular recognition within a calix[6]arene funnel complex.

Author information

1
Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Unité Mixte de Recherche 8601, Centre National de la Recherche Scientifique, Université Paris Descartes (Paris 5), 45 Rue des Saints-Pères, Paris, France.

Abstract

A multipoint recognition system based on a calix[6]arene is described. The calixarene core is decorated on alternating aromatic subunits by 3 imidazole arms at the small rim and 3 aniline groups at the large rim. This substitution pattern projects the aniline nitrogens toward each other when Zn(II) binds at the Tris-imidazole site or when a proton binds at an aniline. The XRD structure of the monoprotonated complex having an acetonitrile molecule bound to Zn(II) in the cavity revealed a constrained geometry at the metal center reminiscent of an entatic state. Computer modeling suggests that the aniline groups behave as a tritopic monobasic site in which only 1 aniline unit is protonated and interacts with the other 2 through strong hydrogen bonding. The metal complex selectively binds a monoprotonated diamine vs. a monoamine through multipoint recognition: coordination to the metal ion at the small rim, hydrogen bonding to the calix-oxygen core, CH/pi interaction within the cavity's aromatic walls, and H-bonding to the anilines at the large rim.

PMID:
19237564
PMCID:
PMC2705605
DOI:
10.1073/pnas.0811663106
[Indexed for MEDLINE]
Free PMC Article

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