Chemists were able to directly observe the coordinated vibrations between molecules bound together by hydrogen bonds - this is the first time ever that this type of chemical bond, found in nature in almost every biological system at the molecular level, has been directly observed.
![The interactions of the hydrogen bonds cause the atoms in each of the molecules of the dimer to vibrate at a common rate. [Courtesy of L. De Marco/UChicago]](https://www.hayadan.org.il/images/content3/2014/07/hydrogen-connections.jpg.webp)
Using a newly developed infrared radiation source that operates at an extremely fast rate, chemists were able to directly observe the coordinated vibrations between molecules bound together by hydrogen bonds - this is the first time ever that this type of chemical bond, found in nature in almost every system Biological at the molecular level, directly observed.
Using a newly developed source of infrared radiation that operates at an extremely fast rate, chemists at the University of Chicago were able to directly observe hydrogen bonds. The research findings have long been published in the scientific journal The Journal of Chemical Physics.
The researchers took advantage of two-dimensional infrared spectroscopic methods as a new tool to directly observe the two hydrogen bond partners," said principal investigator Andrei Tokmakoff. "With these methods, there are possibilities of spectral content and bandwidths that provide a real observation of a wide part of the vibrational spectrum of molecules. The method paves the way to examine how very different types of vibrations in different molecules react with each other."
The researchers decided to use two-dimensional infrared spectroscopy in order to directly characterize structural parameters such as intermolecular distances and the nature of the hydrogen bond configurations, given the fact that this information can be encoded in the signals obtained as a result of the intermolecular interactions between the solvent to dissolve "What we did was to vibrate the bonds in one molecule while watching the effects it had on the other molecule," said the researcher. "In our experiment, what's actually happening is you're vibrating both molecules at the same time because they're tightly bound."
Hydrogen bonds (Wikipedia) make up the force of attraction between the slightly negatively charged end and the slightly positively charged end of neutral molecules, such as water. Although water is a special case due to unique polarization properties, hydrogen bonds can form between a wide variety of molecules that include electrically polarized atoms in their structure, when these bonds range in strength from a weakly polarized bond to a bond close in strength to a covalent bond. Hydrogen bonds play an important part in the activity of large biological molecules (such as DNA and RNA, proteins, etc.) and are an important factor in the discovery of new drugs.
For the first observation of hydrogen bonds, the researchers used the substance N-methylacetamide (Wikipedia), a peptide molecule that forms dimers connected together through hydrogen bonds of medium strength when they are in an organic solvent, this is due to the electrical polarization present in the nitrogen-hydrogen and carbon-oxygen bonds found in the molecule. Using adapted instrumentation, the researchers were able to record the vibrational patterns of the two peptide units.
"All the internal vibrations of hydrogen-bonded molecules that we've looked at have become entangled and complicated; they can't just be thought of as a simple sum of the two separate parts," notes the lead researcher. Other research works conducted in the scientist's laboratory include observing the dynamics and structure of water molecules surrounding biological molecules such as proteins and DNA. "Since we know that water has consequences everywhere, especially in biological systems, we must note that many studies in computational biology ignore the fact that water have real structure and real quantum properties of their own."
The interactions of the hydrogen bonds cause the atoms in each of the molecules of the dimer to vibrate at a common rate. [Courtesy of L. De Marco/UChicago]
