Is a hydrogen bond possible without a hydrogen atom

12.05.2017 20:00

Formation of hydrogen bonds observed for the first time

Reto Caluori Communication & Marketing
University of Basel

For the first time, scientists have succeeded in using an atomic force microscope to study the formation of hydrogen bonds in a single molecule. This is what researchers from the network of the Swiss Nanoscience Institute at the University of Basel report in the journal “Science Advances”.

Hydrogen is the most common element in the universe and a component of almost all organic compounds. Molecules and sections of macromolecules are connected to one another via hydrogen atoms. These interactions are called hydrogen bonds (or hydrogen bonds for short). They play a major role in nature, as they are responsible for the special properties of proteins or nucleic acids and, for example, also ensure that water has a high boiling temperature.

A spectroscopic or electron microscopic analysis of hydrogen and the hydrogen bonds in molecules has not been possible up to now, and atomic force microscopy has not provided any clear results either.

Dr. Shigeki Kawai from Professor Dr. Ernst Meyer from the Swiss Nanoscience Institute and Department of Physics at the University of Basel has now succeeded in examining hydrogen atoms in individual cyclic hydrocarbon compounds using a high-resolution atomic force microscope.

Appropriate molecules enable representation

In a collaboration with colleagues from Japan, the researchers selected compounds with a configuration similar to that of a propeller. These propellanes are arranged on a surface in such a way that two hydrogen atoms always point upwards. If the tip of the atomic force microscope, functionalized with carbon monoxide, is brought close enough to these two hydrogen atoms, hydrogen bonds form, which can be examined.

Hydrogen bonds are significantly weaker than chemical bonds, but much stronger than intermolecular van der Waals bonds. The measured forces and distances between the oxygen atoms at the tip of the atomic force microscope and the hydrogen atoms in the propellane correspond exactly to the calculations carried out by partners from Aalto University in Finland. They show that the bond is clearly a hydrogen bond. On the basis of the measurements, the significantly weaker van der Waals forces as well as the stronger ionic bonds can be excluded.

With this study, the researchers from the network of the Swiss Nanoscience Institute at the University of Basel are opening up new ways to identify three-dimensional molecules such as nucleic acids or polymers.

Original contribution

Shigeki Kawai, Tomohiko Nishiuchi, Takuya Kodama, Peter Spijker, Rémy Pawlak, Tobias Meier, John Tracey, Takashi Kubo, Ernst Meyer, Adam S. Foster
Direct quantitative measurement of the C = O ··· H-C bond by atomic force microscopy
Science Advances (2017), doi: 10.1126 / sciadv.1603258

Further information

Prof. Dr. Ernst Meyer, University of Basel, Department of Physics, phone +41 61 207 37 24, email: [email protected]

Features of this press release:
Journalists, scientists, everyone
Physics / astronomy
Research results, scientific publications