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) (Mn-12(acetate)(16)), which is transferred from solution onto a Au(111) substrate held in ultrahigh vacuum using electrospray deposition (UHV-ESD). The deposited Mn-12(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 Mn-12(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 Mn-12(acetate)(16) onto a surface that has been prepatterned with a hydrogen-bonded supramolecular network provides additional control of lateral organization.