title: Molecular recognition and self-assembly special feature: Multipoint molecular recognition within a calix[6]arene funnel complex.
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.
authors.affiliation: 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.
authors.forename: David
authors.initials: D
authors.lastname: Coquière
authors.forename: Aurélien
authors.initials: A
authors.lastname: de la Lande
authors.forename: Sergio
authors.initials: S
authors.lastname: Martí
authors.forename: Olivier
authors.initials: O
authors.lastname: Parisel
authors.forename: Thierry
authors.initials: T
authors.lastname: Prangé
authors.forename: Olivia
authors.initials: O
authors.lastname: Reinaud
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry; D001665:Binding Sites; D047250:Calixarenes / Q000737:chemistry*; D006860:Hydrogen Bonding; D007093:Imidazoles / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry; D010636:Phenols / Q000737:chemistry*; D011522:Protons; D014961:X-Ray Diffraction; D015032:Zinc / Q000737:chemistry*
chemical_list: D000814:Aniline Compounds; D007093:Imidazoles; D009942:Organometallic Compounds; D010636:Phenols; D011522:Protons; C476540:calix(6)arene; D047250:Calixarenes; D015032:Zinc; C023650:aniline