Xanthene[n]arenes: Exceptionally Large, Bowl-shaped Macrocyclic Building Blocks Suitable for Self-Assembly

A new class of macrocycles denoted as “xanthene[n]arenes” was synthesized. In contrast to most other macrocycles, they feature a rigid bowl-shape, required for the synthesis of cavitands and for the self-assembly to molecular capsules via non-covalent interactions. The derivatization potential of the novel macrocycles was demonstrated on the xanthene[3]arene scaffold. Beside a deep cavitand, a modified macrocycle was synthesized that self-assembles into a hydrogen-bonded tetrameric capsule. Both supramolecular systems display host-guest binding properties, demonstrating the potential of xanthene[n]arenes as a new set of macrocyclic building blocks.