Density Control of Dodecamanganese Clusters Anchored on Silicon(100)

Abstract

A synthetic strategy to control the density of Mn12 clusters anchored on silicon(100) was investigated. Diluted monolayers suitable for Mn12 anchoring were prepared by Si-grafting mixtures of the methyl 10-undecylenoate precursor ligand with 1-decene spectator spacers. Different ratios of these mixtures were tested. The grafted surfaces were hydrolyzed to reveal the carboxylic groups available for the subsequent exchange with the [Mn12O12(OAc)16(H2O)4]4 H2O2 AcOH cluster. Modified surfaces were analyzed by attenuated total reflection (ATR)-FTIR spectroscopy, X-ray photoemission spectroscopy (XPS), and AFM imaging. Results of XPS and ATR-FTIR spectroscopy show that the surface mole ratio between grafted ester and decene is higher than in the source solution. The surface density of the Mn12 cluster is, in turn, strictly proportional to the ester mole fraction. Well-resolved and isolated clusters were observed by AFM, using a diluted ester/decene 1:1 solution.

Identification of linker molecules suited for deposition and study of Mn12 single molecule magnets on Au surfaces

“…3͑b͔͒. Such artifacts could rarely be observed for Mn 12 -pfb on 4-MOBCA with the effect being less distinct. This can be explained by the lower conductivity of the Mn 12 -pfb/4-MMTBA system ͑see below͒.…”

“…The results demonstrate the general suitability of the deposition via a ligand exchange reaction but, on the other hand, reveal the need for a compromise between flexibility and conductivity of the prefunctionalization layer to avoid measurement artifacts. These observations are discussed with respect to a previous attempt to deposit ordered monolayers of Mn 12 14 STM and STS measurements were performed using an Omicron VT AFM/STM incorporated into an Omicron Multiprobe UHV system with a base pressure of 10 −11 mbar. The STM tips were made of tungsten and had been flash annealed by electron bombardment after electrochemical etching.…”

“…11 Moreover, there have been attempts to deposit Mn 12 molecules on Si surfaces by related chemical techniques. 12 Nonetheless, after utilizing wet chemical methods for deposition of Mn 12 on surfaces no profound evidence for any ordering of the molecular monolayer was obtained so far although a partial ordering of a Mn 12 monolayer has been reported. 10 In this work, we present an investigation of two different prefunctionalization layers allowing for the deposition of Mn 12 molecules via the ligand exchange reaction.…”

Investigation of the stability of Mn12 single molecule magnets

“…However, experiments on the magnetic properties of individual Mn 12 molecules require the ability to deposit and address intact molecules on a surface. With respect to this, there have been several approaches to graft Mn 12 molecules on different surfaces [8][9][10][11][12][13][14]. However, the conservation of the structural, electronic, and magnetic properties of Mn 12 SMMs upon deposition on surfaces could not be unambiguously confirmed so far.…”

Experimental observation of a band gap in individual Mn12 molecules on Au(111)

“…11 Scanning tunneling microscopy ͑STM͒ has also been implemented to probe Mn 12 molecules deposited on different surfaces. 8,[12][13][14][15][16][17] However, these studies have mainly been limited to the investigation of the Mn 12 layer topography without addressing the electronic properties of the Mn 12 molecules. Moreover, the existing difficulties with the preparation of intact molecular surface layers hamper the investigation of the molecular electronic structure and transport.…”