Abstract
In order to form anion-driven 3D clusters, we have attempted to prepare radially arranged oligomers of dipyrrolyldiketone boron complexes as acyclic anion receptors. In fact, the trefoil-shaped trimers, which were obtained by Suzuki coupling, showed a variety of anion-driven assemblies such as helical assemblies and cage-like clusters, depending on the peripheral substituents and substituted positions of the 1,3,5-triphenylbenzene cores. The trimer shows higher anion-binding affinities, due to multiple binding sites. For receptor hexamers, which were obtained by cyclotrimerization reaction of ethynyl-bridged dimers, complicated conformations were observed in the absence of anions. Upon the addition of Cl–, NMR signals of pyrrole NH were shifted to downfield, suggesting the formations of [n+m]-type assemblies.
