Self-assembly of a supramolecular hexagram and a supramolecular pentagram

Five- and six-pointed star structures occur frequently in nature as flowers, snow-flakes, leaves and so on. These star-shaped patterns are also frequently used in both functional and artistic man-made architectures. Here following a stepwise synthesis and self-assembly approach, pentagonal and hexagonal metallosupramolecules possessing star-shaped motifs were prepared based on the careful design of metallo-organic ligands (MOLs). In the MOL design and preparation, robust ruthenium-terpyridyl complexes were employed to construct brominated metallo-organic intermediates, followed by a Suzuki coupling reaction to achieve the required ensemble. Ligand LA (VRu2+X, V = bisterpyridine, X = tetraterpyridine, Ru = Ruthenium) was initially used for the self-assembly of an anticipated hexagram upon reaction with Cd2+ or Fe2+; however, unexpected pentagonal structures were formed, that is, [Cd(5)LA(5)](30+) and [Fe(5)LA(5)](30+). In our redesign, LB [V(Ru2+X)(2)] was synthesized and treated with 60 degrees V-shaped bisterpyridine (V) and Cd2+ to create hexagonal hexagram [Cd12V3LB3](36+) along with traces of the triangle [Cd3V3](6+). Finally, a pure supramolecular hexagram [Fe12V3LB3](36+) was successfully isolated in a high yield using Fe2+ with a higher assembly temperature.