Calixphyrins. Hybrid macrocycles at the structural
crossroads between porphyrins and calixpyrroles*
Jonathan L. Sessler1**, Rebecca S. Zimmerman1, Christophe
Bucher1, Vladimír Král2, and Bruno Andrioletti3
1Department of Chemistry & Biochemistry
and the Institute for Cellular and Molecular Biology, The University
of Texas at Austin, TX 78712, USA; 2Department of Analytical Chemistry,
Institute of Chemical Technology, 16628 Prague 6, Technická
5, Czech Republic; 3Laboratoire de Synthèse Organique et Organométallique,
Université P. et M. Curie, UMR 7611, Tour 44, 1er Etage, BP
181, 4 Place Jussieu, 75252 Paris Cedex, France
Abstract: Calixphyrins are a class of hybrid
molecules that lie at the structural crossroads between porphyrins
and calixpyrroles. Porphyrins, long known for their versatile metal
cation coordination chemistry, are macrocycles that contain only sp2-hybridized
bridging meso carbon atoms within their framework. Calix[n]pyrroles,
on the other hand, are porphyrin analogs that contain pyrroles bridged
exclusively by sp3 meso carbon centers, and in recent years have been
shown to display remarkable anion-binding properties. Calix[n]phyrins
bear analogy to both the porphyrins and calixpyrroles and are macrocyclic
analogs that contain a mixture of sp2- and sp3-hybridized meso carbon
bridges. This leads to partial interruptions in the conjugation pathway
of the molecule, introduces novel structural features, and leads to
interesting anion and cation recognition properties. It also allows
for modular syntheses. In the present paper, the chemistry of calix[n]phyrins,
still at an early stage of exploration, is reviewed.
*Lecture presented at the 38th IUPAC
Congress/World Chemistry Congress 2001, Brisbane, Australia, 1-6 July
2001. Other presentations are published in
this issue, pp.1033-1145.
**Corresponding author.