Self-assembly of a supramolecular hexagram and a supramolecular pentagram

摘要

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 ( VRu 2+ 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(Ru 2+ X) ₂ ] was synthesized and treated with 60° V-shaped bis terpyridine ( V ) and Cd2+ to create hexagonal hexagram [Cd ₁₂ V ₃ LB ₃ ] 36+ along with traces of the triangle [Cd ₃ V ₃ ] 6+ . Finally, a pure supramolecular hexagram [Fe ₁₂ V ₃ LB ₃ ] 36+ was successfully isolated in a high yield using Fe2+ with a higher assembly temperature.