Anja Nickel

Moving Nanostructures: Pulse-Induced Positioning of Supramolecular Assemblies

For the development of nanoscale devices, the manipulation of single atoms and molecules by scanning tunneling microscopy is a well-established experimental technique. However, for the construction of larger and higher order structures, it is important to move not only one adsorbate but also several at the same time. Additionally, a major issue in standard manipulation experiments is the strong mechanical interaction of the tip apex and the adsorbate, which can damage the system under investigation. Here, we present a purely electronic excitation method for the controlled movement of a weakly interacting assembly of a few molecules. By applying voltage pulses, this supramolecular nanostructure is moved in a controlled manner without losing its collective integrity. Depending on the polarity and location of the applied voltage, the movement can be driven in predefined directions. Our gentle purely electronic approach for the controlled manipulation of nanostructures opens new ways to construct molecular devices.

Synthesis and STM Imaging of Symmetric and Dissymmetric Ethynyl‐Bridged Dimers of Boron–Subphthalocyanine Bowl‐Shaped Nanowheels

The futures wheel: A new class of wheels, based on subphthalocyanine fragments, for future incorporation in functional nanovehicles is reported (see figure). The syntheses of a symmetric wheel, a nitrogen-tagged wheel, and their ethynyl-bridged homodimers are presented. Theoretical calculations and STM imaging demonstrate the advantage of a bowl-shaped structure and the efficiency of the tag for STM imaging.

STM manipulation of a subphthalocyanine double-wheel molecule on Au(111).

A new class of double-wheel molecules is manipulated on a Au(111) surface by the tip of a scanning tunneling microscope (STM) at low temperature. The double-wheel molecule consists of two subphthalocyanine wheels connected by a central rotation carbon axis. Each of the subphthalocyanine wheels has a nitrogen tag to monitor its intramolecular rolling during an STM manipulation sequence. The position of the tag can be followed by STM, allowing us to distinguish between the different lateral movements of the molecule on the surface when manipulated by the STM tip.

Supramolecular Rotor and Translator at Work: On-Surface Movement of Single Atoms

A supramolecular nanostructure composed of four 4-acetylbiphenyl molecules and self-assembled on Au (111) was loaded with single Au adatoms and studied by scanning tunneling microscopy at low temperature. By applying voltage pulses to the supramolecular structure, the loaded Au atoms can be rotated and translated in a controlled manner. The manipulation of the gold adatoms is driven neither by mechanical interaction nor by direct electronic excitation. At the electronic resonance and driven by the tunneling current intensity, the supramolecular nanostructure performs a small amount of work of about 8 × 10(-21) J, while transporting the single Au atom from one adsorption site to the next. Using the measured average excitation time necessary to induce the movement, we determine the mechanical motive power of the device, yielding about 3 × 10(-21) W.