Conjugated shape-persistent macrocycles via Schiff-base condensation: New motifs for supramolecular chemistry*

Shape-persistent conjugated macrocycles are challenging synthetic targets with interesting properties and potential for a number of applications. In contrast to the standard kinetic approaches to macrocycles, reversible Schiff-base condensation offers a one-step, thermodynamic route to large macrocycles. These macrocycles, which feature “salen”-type coordination environments and an interior that resembles a crown-ether have interesting properties themselves and are novel substrates for supramolecular chemistry. This short review article places conjugated [3+3] Schiff-base macrocycles in the context of shape-persistent macrocycles and discusses their synthesis. In addition, specific examples of supramolecular chemistry with these macrocycles highlight their unique behavior when compared to conjugated carbon-based macrocycles and flexible crown-ethers.