Ester formation at the liquid-solid interface.

A chemical reaction (esterification) within a molecular monolayer at the liquid-solid interface without any catalyst was studied using ambient scanning tunneling microscopy. The monolayer consisted of a regular array of two species, an organic acid (trimesic acid) and an alcohol (undecan-1-ol or decan-1-ol), coadsorbed out of a solution of the acid within the alcohol at the interface of highly oriented pyrolytic graphite (HOPG) (0001) substrate. The monoester was observed promptly after reaching a threshold either related to the increased packing density of the adsorbate layer (which can be controlled by the concentration of the trimesic acid within the alcoholic solution via sonication or extended stirring) or by reaching a threshold with regards to the deposition temperature.

(Metallo)porphyrins for potential materials science applications.

The bottom-up approach to replace existing devices by molecular-based systems is a subject that attracts permanently increasing interest. Molecular-based devices offer not only to miniaturize the device further, but also to benefit from advanced functionalities of deposited molecules. Furthermore, the molecules itself can be tailored to allow via their self-assembly the potential fabrication of devices with an application potential, which is still unforeseeable at this time.

Role of the deposition temperature on the self-assembly of the non-planar molecule benzene-1,3,5-triphosphonic acid (BTP) at the liquid-solid interface.

Benzene-1,3,5-triphosphonic acid (BTP) contains three non-planar phosphonic acid groups which enable three-dimensional hydrogen bonding. Because of these versatile 3D functional groups, BTP is an interesting intermediate to design both 2D and 3D supramolecular hydrogen-bonded architectures and organic-inorganic hybrid frameworks. However, the adsorption of BTP has surprisingly not been the subject of scanning tunneling microscopy (STM) investigations so far.

Surface-confined 2D polymerization of a brominated copper-tetraphenylporphyrin on Au(111).

A coupling-limited approach for the Ullmann reaction-like on-surface synthesis of a two-dimensional covalent organic network starting from a halogenated metallo-porphyrin is demonstrated. Copper-octabromo-tetraphenylporphyrin molecules can diffuse and self-assemble when adsorbed on the inert Au(111) surface. Splitting-off of bromine atoms bonded at the macrocyclic core of the porphyrin starts at room temperature after the deposition and is monitored by X-ray photoelectron spectroscopy for different annealing steps.