Crafting Intriguing Supramolecular Snub Cubes: A Creative Journey

Researchers have introduced novel supramolecular snub cubes—assemblies of 2,712 atoms in polyhedral forms composed of 12 similar helical macrocycles interconnected by 144 weak hydrogen bonds. Snub cubes represent Archimedean solids featuring 60 edges, 38 faces, and 24 vertices. These structures can exhibit right-handed or left-handed orientations, and likewise, the supramolecular snub cubes can exhibit right or left-handed characteristics, determined by the stereochemistry of the macrocycles employed in their construction. Each supramolecular snub cube contains unique compartments within its structure, facilitating the simultaneous hosting of two different guest components. The developers of these novel snub cube supramolecules propose that they could be utilized in chiral separations or asymmetric catalysis (Nature 2025, DOI: 10.1038/s41586-024-08266-3).

Huang Wu and the late J. Fraser Stoddart from the University of Hong Kong, alongside Wenping Hu and Yu Wang from Tianjin University, spearheaded the initiative to create and analyze the snub cube supramolecules. The chemists express that their inspiration came from biological encapsulating structures such as virus capsids and the iron-storing protein ferritin.

Previously, supramolecular snub cubes have been created. The initial one was synthesized in 1997 by Leonard R. MacGillivray and Jerry L. Atwood, who were affiliated with the University of Missouri–Columbia at that time. That earlier complex was maintained by merely 60 hydrogen bonds. The current snub cube supramolecules represent the first instances to be formed stereoselectively. The chemists successfully produced exclusively right- or left-handed snub cubes utilizing the stereochemistry of the initial helical macrocycles.

Shiki Yagai, a researcher in supramolecular materials at Chiba University, who was not part of this study, comments that the finding that small chiral elements can assemble noncovalently into chiral nanostructures absent of proteins is “truly remarkable.” He added in an email that “this pioneering material showcases an extraordinary level of hierarchical self-organization, matching the complexity and sophistication seen in biological systems.”

Peter J. Stang, a specialist in supramolecular assembly at the University of Utah and who also did not participate in this research, shared in an email that “this represents daring, innovative chemical science which propels the field of supramolecular chemistry forward and holds the promise of enhancing our understanding and insights into this captivating and expansive domain.”

Wu reveals to C&EN that the discovery of the snub cubes was coincidental. He synthesized a variety of macrocycles in the hopes that one would assemble into a complex polyhedron, but he had not specifically aimed to create a snub cube. After producing the essential helical macrocycle and noticing its assembly into a more intricate architecture, it took him a while to recognize that it had adopted the snub cube configuration. Additionally, Wu recounts that the day following his presentation of the crystal structure of the snub cube to Stoddart, Stoddart admitted he had a sleepless night due to his excitement about the complex.

Moving forward, Wu expresses his desire to experiment with artificial intelligence for the design of supramolecular snub cubes of varying sizes, as well as mechanically interlocked snub cubes.