Supramolecular Chemistry of Acyclic Oligopyrroles

Abstract

AbstractAcyclic π‐conjugated oligopyrrole derivatives, though not extensively studied, often have more advantages as anion receptors and metal‐coordination ligands than their cyclic counterparts. This is due to the formation of versatile complexes and supramolecular assemblies, although they do require conformational changes by guest binding. Of the linear oligopyrroles, oligomeric derivatives of dipyrrins bridged by π‐conjugated spacers behave as building subunits and form coordination oligomers and discrete coordination nanorings. In contrast, pyrrole oligomers with hydrogen‐bond‐acceptor site(s) have yielded unique morphologies as supramolecular assemblies and micro‐ and nanometer‐scale structures by means of hydrogen‐bonding interactions. Furthermore, a new class of acyclic anion receptors, namely, BF2 complexes of dipyrrolyl diketones, has been shown to interact with anions by means of the pyrrole NH group and bridging CH interactions. Inversion of the pyrrole rings was found to be essential to capture anions by using these binding sites. Aryl substitution of the receptors as π‐extended derivatives has enabled the formation of assemblies such as supramolecular organogels that can be controlled by the addition of anions.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)