From C 60 "trilliumons" to "trilliumenes:" Self-assembly of 2D fullerene nanostructures on metal-covered silicon and germanium

We discovered a set of C nanostructures that appear to be constructed using a universal building block made of four C molecules on Si(111) or Ge(111) surfaces covered by an atomic layer of Tl, Pb, or their compound. The building block is a four-C cluster having a shape reminiscent of the three-petal flower "white trillium." Therefore, we call it "trilliumon" and the various 2D ordered nanostructures derived from it "trilliumenes." Self-assembly of the trilliumenes is a result of an intricate interplay among the adsorbed C molecules, metal atoms, and semiconductor substrates. Remarkably, all metal layers triggering formation of trilliumenes on the Si(111) surface have recently been reported to be the thinnest 2D superconductors. In this respect, the trilliumenes show promise to be 2D nanostructured superconductors whose properties are awaiting their exploration.