Functional ligand directed assembly and electronic structure of Sn18-oxo wheel nanoclusters.

A bilayer hexagonal wheel Sn18-oxo cluster, as the largest tin-oxo wheel to date, was successfully constructed by structural directing of organic ligands. Moreover, the ligands show important effects on the electronic structure and third-order nonlinear optical properties of the Sn18-oxo wheel, which is demonstrated by detailed theoretical calculations.