Huge 2-D metallo-supramolecule

In its quest to make a really big 2-D nanostructure, Xiaopeng Li’s University of South Florida team pulled out all the stops. It used both intra- and intermolecular self-assembly to build a grid of hexagons held together with ruthenium and iron ions. This monster of a metallo-supramolecule, made with help from collaborators at Argonne National Laboratory, Ohio University, and many other institutes, measures about 20 nm across (Nat. Chem. 2020, DOI: 10.1038/s41557-020-0454-z). Li says it ranks among the largest discrete metallo-supramolecules produced to date. Each hexagon of the grid is made from organic linkers that stick out in three directions. At all three ends of the spiky molecule are the nitrogen-containing terpydine ligands that complex ruthenium ions. These combine until you get a hexagonal building block with some unbound ligands. Add iron(II), and the hexagons start snapping together to make a linked-up lattice. The iron ions’ positions can produce different isomers. This giant molecule is more than a novelty. The team hopes to replace the iron with other metal ions, such as cobalt, to produce variations that can act as single-molecule information storage devices by using different spin states.