Single-Molecule Magnets:  A New Approach To Investigate the Electronic Structure of Mn12 Molecules by Scanning Tunneling Spectroscopy

A new approach to the deposition of Mn12 single-molecule magnet monolayers on the functionalized Au(111) surface optimized for the investigation by means of scanning tunneling spectroscopy was developed. To demonstrate this method, the new Mn12 complex [Mn12O12(O2CC6H4F)16(EtOH)4]·4.4CHCl3 was synthesized and characterized. In MALDI-TOF mass spectra the isotopic distribution of the molecular ion peak of the latter complex was revealed. The complex was grafted to Au(111) surfaces via two different short conducting linker molecules. The Mn12 molecules deposited on the functionalized surface were characterized by means of scanning tunneling microscopy showing homogeneous monolayers of highest quality. Scanning tunneling spectroscopy measurements over a wider energy range compared with previous results could be performed because of the optimized Au(111) surface functionalization. Furthermore, the results substantiate the general suitability of short acidic linker molecules for the preparation of Mn12 monolayers via ligand exchange and represent a crucial step toward addressing the magnetic properties of individual Mn12 single-molecule magnets.