Self-assembled aggregates formed by single-molecule magnets on a gold surface

The spontaneous ordering of molecules into two-dimensional self-assembled arrays is commonly stabilized by directional intermolecular interactions that may be promoted by the addition of specific chemical side groups to a molecule. In this paper, we show that self-assembly may also be driven by anisotropic interactions that arise from the three-dimensional shape of a complex molecule. We study the molecule Mn12O12(O2CCH3)16(H2O)4 (Mn12(acetate)16), which is transferred from solution onto a Au(111) substrate held in ultrahigh vacuum using electrospray deposition (UHV-ESD). The deposited Mn12(acetate)16 molecules form filamentary aggregates because of the anisotropic nature of the molecule–molecule and molecule–substrate interactions, as confirmed by molecular dynamics calculations. The fragile Mn12O12 core of the Mn12(acetate)16 molecule is compatible with the UHV-ESD process, which we demonstrate using near-edge X-ray adsorption fine-structure spectroscopy. UHV-ESD of Mn12(acetate)16 onto a surface that has been prepatterned with a hydrogen-bonded supramolecular network provides additional control of lateral organization.