title: Structural and binding features of cofacial bis-porphyrins with calixarene spacers: pac-man porphyrins that can chew.
abstract: Based on the efficient combination of calixarene spacers and acetylenic porphyrin derivatives, a new generation of cofacial bis-porphyrins has been synthesized. The first crystal structure of a cofacial bis-porphyrin-calixarene conjugate is reported. Their unique architectural features, analogous to those of pac-man-type bis-porphyrins, allow these calixarene-porphyrin conjugates to adapt their shape to the size of bidentate guests, such as diazabicyclo[2.2.2]octane (dabco) and 1,4-pyrazine. The predefined, cofacial arrangement of the porphyrin moieties observed in the solid state and in solution results in extremely high affinities (in the range of 10(9) M(-1)) for these guests. The 1,3-alternate calixarene conformations afford "open-mouth" pac-man structures whose ability to bite on nitrogen bidentates depends on their functionalization. A cone conformer provides a much more flexible structure that exhibits the highest affinity for dabco and pyrazine.
authors.affiliation: Laboratoire de Chimie des Ligands à Architecture Controlée, Institut de Chimie, Université Louis Pasteur, Strasbourg, France.
authors.forename: Danica
authors.initials: D
authors.lastname: Jokic
authors.forename: Corinne
authors.initials: C
authors.lastname: Boudon
authors.forename: Grégory
authors.initials: G
authors.lastname: Pognon
authors.forename: Michel
authors.initials: M
authors.lastname: Bonin
authors.forename: Kurt J
authors.initials: KJ
authors.lastname: Schenk
authors.forename: Maurice
authors.initials: M
authors.lastname: Gross
authors.forename: Jean
authors.initials: J
authors.lastname: Weiss