Deposition and Self-Assembly of Large Magnetic Molecules

Abstract

We have used two different unconventional preparation techniques, namely, pulse injection and rapid heating, to deposit large trinuclear transition-metal complexes onto a Au(111) surface under ultrahigh-vacuum conditions. Both techniques turn out to provide a clean preparation and leave the molecules intact upon deposition. While pulse injection leads to isolated molecules on the surface, rapid heating yields close-packed ordered monolayer islands. From a comparison of topographies and electronic structures we conclude that both molecule−substrate and intermolecular interactions are relatively weak. We discuss the reasons for the appearance of the different structures and give a detailed comparison of both deposition techniques which allows us to evaluate their specific advantages and drawbacks. Our results show that these relatively simple and cost-efficient preparation techniques are suitable for nanoscale studies of large molecules such as single-molecule magnets.

Half‐Integer Spin Triangles: Old Dogs, New Tricks

“…However,t his perspectiveh ingesu pon the better understanding of their chemical and physical stability upon surface deposition, as till poorly studied subject. Surface deposition experiments have shown that chromium(III) carboxylate triangles [233] and the [Cu 3 (talen tBu2 )] complex [234] retain their structural integrity,a nd are encouraging in that regard. Clearly,h owever,f urthers tudies are required for as olid grasp of the issue, as achieved in the case of surface-deposited SMMs.…”

Correlating electronic and magnetic coupling in large magnetic molecules via scanning tunneling microscopy

“…Unfortunately, a standard thermal sublimation was not feasible due to the fragility of these large complexes. We therefore utilized a pulse-injection technique for a clean in situ deposition of the molecules, which we have reported earlier [15]. After the preparation, the sample was immediately transferred into the cryogenic STM (operated at T = 5 K) and topography images were taken to identify single molecules and to acquire local tunneling spectra (dI/dV vs V, open feedback) as well as spectroscopic maps (dI/dV vs position, constant-current mode).…”

“…In first approximation, dI/dV reflects the LDOS, where negative (positive) voltages correspond to (un)occupied states, and V = 0 defines the Fermi energy (E F ). Details of the sample preparation and STM/STS characterization have been published previously [15,34]. Figure 3 presents STM images of both molecules on Au(111).…”

“…To verify this possibility, we also studied a highly ordered close-packed monolayer of [(talen t−Bu 2 )Cu 3 ] [ Fig. 5(d)] [15]. Out of more than 200 molecules studied, none initially showed an asymmetry.…”

“…However, most potential applications are thought to require the slow relaxation at higher temperatures as well as a controlled deposition on conductive surfaces (i.e., electrode contacts) with single-molecule addressability [11][12][13][14]. Besides practical difficulties for a controlled deposition of SMMs on surfaces [15], studies on various molecular magnetic systems like the archetype SMM Mn 12 [16,17], or on transition-metal phthalocyanines and porphyrins [18][19][20][21], showed that the surface can significantly alter the SMM properties via hybridization, charge transfer, and ligand-field modifications. This can improve but also destroy SMM properties, as is the case for Mn 12 .…”