For the first time, scientists have succeeded in studying the strength of hydrogen bonds in a single molecule using an atomic force microscope. Molecules and sections of macromolecules are connected to one another via hydrogen atoms, an interaction known as hydrogen bonding.
To date, it has not been possible to conduct a spectroscopic or electron microscopic analysis of hydrogen and the hydrogen bonds in single molecules, and investigations using atomic force microscopy have also not yielded any clear results.
Dr. Shigeki Kawai, from Professor Ernst Meyer’s team at the Swiss Nanoscience Institute and the Department of Physics at the University of Basel, has now succeeded in using a high-resolution atomic force microscope to study hydrogen atoms in individual cyclic hydrocarbon compounds.
If the tip of the atomic force microscope, which is functionalized with carbon monoxide, is brought close enough to these hydrogen atoms, hydrogen bonds are formed that can then be examined.
Hydrogen bonds are much weaker than chemical bonds, but stronger than intermolecular van der Waals interactions.
The measured forces and distances between the oxygen atoms at the tip of the atomic force microscope and the propellane’s hydrogen atoms correspond very well to the calculations performed by Prof. Adam S. Foster from Aalto University in Finland.