Kiel University
Most technical functional units are built bit by bit according to a well-designed construction plan. The components are sequentially put in place by humans or machines. Life, however, is based on a different principle. It starts bottom-up with molecular self-assembly. The crystallization of sugar or salt are simple examples of self-assembly processes, where almost perfect crystals form from molecules that randomly move in a solution. To better understand the growth of macroscopic structures from molecules, a research team of physicists and chemists of Kiel University has mimicked such processes with custom-made molecules. As recently reported in the journal Angewandte Chemie they fabricated a variety of patterns over a wide range of sizes including the largest structures reported so far.
The researchers deposited triangular molecules (methyltrioxatriangulenium) on gold and silver surfaces and observed their self-assembly into honeycomb superstructures using a scanning tunneling microscope. The structures are comprised of periodic patterns with controllable sizes. "Our largest fabricated patterns contain subunits of 3.000 molecules each, which is approximately 10 times more than previously reported", says Dr. Manuel Gruber, a physicist from Kiel University. The team also developed a model of the intermolecular forces that drive the self-assembly. "The unique feature of our results is that we can explain, predict and even control their size", Gruber continues.
The detailed understanding of the driving forces controlling the size of the patterns holds promises for nanotechnology applications, and in particular for functionalization of surfaces. It may be envisioned to tune various physical properties like electronic, optical or reactivity to gases of a material by controlling the size of the superstructures on its surface.
Coverage-Controlled Superstructures of C3 Symmetric Molecules: Honeycomb versus Hexagonal Tiling
T. Jasper-Toennies, M. Gruber, S. Ulrich, R. Herges and R. Berndt
Angewandte Chemie International Edition (2020)
Contact information:
Rainer Herges
Otto Diels Institute of Organic Chemistry
rherges@oc.uni-kiel.de
Phone: +49 (0)431 880 2440
http://www.otto-diels-institut.de/en/otto-diels-institute-of-organic-chemistry
Manuel Gruber
Surface Physics
gruber@physik.uni-kiel.de
Phone: +49 (0)431 880 5091
http://www.ieap.uni-kiel.de/surface
Silver nanoparticles with diameters of ~10 nm deliver the best performance as electrocatalysts. The silver particles are sprayed onto the electrode together with a conductive carbon powder. The ideal mixture consists of 20 per cent by mass silver and 80 per cent by mass carbon powder. This image was taken using a transmission electron microscope (TEM). © HZB Via electrolysis, CO₂ can be reduced to CO, a raw material for further chemical products such as fuels. Within the GreenQuest Project,...
A flexible metal–organic framework developed by researchers from Institute of Science Tokyo enables the structural determination of large "beyond rule of 5" molecules from microgram-scale samples. Using APF-40 as a crystalline sponge, the researchers determined the structures of 12 pharmaceutical-related molecules, including the 899 Da drug molecule doramectin and trace ivermectin derivatives. The method could aid drug discovery, natural products research, and the characterization of rare...
image: CuZn800@C was constructed via solvothermal method and utilizes the high-temperature volatility of zinc to prepare through calcination at different temperatures, which displays a high methane Faradaic efficiency of 64.5% and a remarkable partial current density of -551.3 mA/cm2 at -1.7 V vs. RHE, along with excellent stability. Zn and Cu form a tandem reaction system. Zn sites promote water splitting to provide protons, while Cu sites reduce the energy barrier for *CO hydrogenation....
