Kandinsky Circles: Self-assembly of Nested Concentric Hexagons
Nested concentric structures widely exist in nature and designed systems with circles, polygons, polyhedra, and spheres sharing the same center or axis. In art field, concentric rings are known as Kandinsky circles named after Wassily Kandinsky, a pioneer in abstract art, because of his prominent and profound painting Color Study-Squares with Concentric Circles. We started Kandinsky Circles project in early 2013. After three years efforts, we assembled four G2 concentric hexagons (J. Am. Chem. Soc., 2016, 138, 9258–9268) however, were unable to reach higher generation because of the challenging synthesis of multitopic terpyridine ligand.
With another two years, we eventually found a solution with consecutive condensation between precursors with primary amines and pyrylium salts. Such modular synthetic approach allows us to prepare multi-armed terpyridine ligand, e.g., octatopic one. Then, three generations (G2−G4) of giant Kandinsky circles were assembled with molecular weight 17,964, 27,713 and 38,352 Da, respectively. Furthermore, such Kandinsky Circles displayed high antimicrobial activity against Gram-positive pathogen methicillin-resistant Staphylococcus aureus (MRSA) through formation of transmembrane channels. Our endeavors will shed light into both antibiotics and supramolecular chemistry field and pave a new avenue into the development and application of antimicrobial agents.
(Nat. Commun., 2018, 9, 1815 )