Monolayers and Programmed Multilayers of Macrocycles and Rotaxanes on Surfaces

STM Studies of Macrocycles Monolayers

Scanning Tunneling Microscopy performed by Peter Broekmann in Bonn revealed interesting patterns of (chiral) metallo-supramolecular macrocycles which assemble in ordered domains on copper surfaces. Similarly, tetralactam macrocycles can be used to pattern surfaces. In STM experiments by Moritz Sokolowski (Bonn), they exhibit different arrangements among which a chiral one forms on the surface, although the macrocycles themselves are achiral.

Programmed Multilayers of Macrocycles and Rotaxanes

Together with Wolfgang Unger (Berlin), multilayers of macrocycles and rotaxanes have been prepared. An underlying self-assembled monolayer is functionalized with pyridines and terpyridines. In a layer-by-layer self-assembly approach, multilayers of metal ions and tetralactam macrocycles and/or (switchable) rotaxanes can be deposited with precisely defined sequence. Films with more than 20 macrocycle layers and an overall thickness in the order of 40-50 nm have been prepared which exhibit pseudorotaxane formation with squaraine axles.

Besides the coordination chemistry approach to deposit multilayers, azide-functionalized SAMs have been studied in order to attach the subsequent layer covalently by click chemistry.

Left: STM image of a chiral, metallo-supramolecular rhomboid on copper. Right: model of a self-assembled monolayer of tetralactam macrocycles coordinated to an underlying template SAM through iron ion binding


Related Publications

STM Experiments with Metallosupramolecular Macrocycles


STM Studies on Tetralactam Macrocycles


Programmed Multilayers of Macrocycles and Rotaxanes


Azide-Functionalized SAMs and Deposition by Click Chemistry