On-surface synthesis of Mn-phthalocyanines with optically active ligands.

The synthesis of novel organic prototypes combining different functionalities is key to achieve operational elements for applications in organic electronics. Here we set the stage towards individually addressable magneto-optical transducers by the on-surface synthesis of optically active manganese-phthalocyanine derivatives (MnPc) obtained directly on a metallic substrate. We created these 2D nanostructures under ultra-high vacuum conditions with atomic precision starting from a simple phthalonitrile precursor with reversible photo-induced reactivity in solution.

Epitaxial growth and structure of cobalt ferrite thin films with large inversion parameter on Ag(001).

Cobalt ferrite ultrathin films with the inverse spinel structure are among the best candidates for spin filtering at room temperature. High-quality epitaxial CoFeO films about 4 nm thick have been fabricated on Ag(001) following a three-step method: an ultrathin metallic CoFe alloy was first grown in coherent epitaxy on the substrate and then treated twice with O, first at room temperature and then during annealing. The epitaxial orientation and the surface, interface and film structure were resolved using a combination of low-energy electron diffraction, scanning tunnelling microscopy, Auger electron spectroscopy and in situ grazing-incidence X-ray diffraction.

Adsorption of iron tetraphenylporphyrin on (111) surfaces of coinage metals: a density functional theory study.

The adsorption of the iron tetraphenylporphyrin (FeTPP) molecule in its deckchair conformation was investigated on Au(111), Ag(111) and Cu(111) surfaces by performing spin-polarized density functional theory (DFT) calculations taking into account both van der Waals (vdW) interaction and on-site Coulomb repulsion. The deckchair conformation of the molecule favours intermolecular π-π-type interactions in a less densely packed monolayer than the saddle conformation. The activation barrier between the two stable magnetic states (high spin, = 2 and intermediate spin, = 1) of the molecule in vacuum disappears upon adsorption on the metal surfaces.

Amplification of conformational effects via tert-butyl groups: hexa-tert-butyl decacyclene on Cu(100) at room temperature.

The design of molecular systems as functional elements for use in next-generation electronic sensors and devices often relies on the addition of functional groups acting as spacers to modify adsorbate-substrate interactions. Although advantageous in many regards, these spacer groups have the secondary effect of amplifying internal conformational effects of the parent molecule. Here we investigate one such molecule-2,5,8,11,14,17-hexa-tert-butyl-decacyclene (HBDC, C60H66)-deposited on Cu(100) at monolayer and submonolayer coverages using an ultra-high vacuum (UHV) scanning tunneling microscope (STM).

Controlling the charge state of a single redox molecular switch.

Scanning tunneling microscopy and dynamic force microscopy in the noncontact mode are used in combination to investigate the reversible switching between two stable states of a copper complex adsorbed on a NaCl bilayer grown on Cu(111). The molecular conformation in these two states is deduced from scanning tunneling microscopy imaging, while their charge is characterized by the direct measurement of the tip-molecule electrostatic force. These measurements demonstrate that the molecular bistability is achieved through a charge-induced rearrangement of the coordination sphere of the metal complex, qualifying this system as a new electromechanical single-molecular switch.