Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The impact of molecular rotation on a peculiar isotope effect on water hydrogen bonds

03.12.2019

Unveiling two deuteration effects on hydrogen-bond breaking process of water isotopomers

The physicochemical and biological properties of hydrogen-bonded systems are significantly affected by nuclear quantum effects including zero-point energies of vibrational modes, proton delocalization, and tunneling effect.


Desorption of water isotopomers (H2O, HDO and D2O) from surfaces of isotope-mixed ice with various H/D compositions.

Credit: NINS/IMS

These originate from the extremely low nuclear mass of hydrogen; thus, hydrogen-bonded systems show remarkable isotope effects upon deuteration. In the 1930s, Ubbelohde first proposed that deuteration elongates and weakens hydrogen bonds in many hydrogen-bonded systems.

Ever since, such an isotope effect has been widely confirmed and is nowadays well known as the "Ubbelohde effect." In contrast, deuterating water molecules in liquid water and ice elongates but strengthens hydrogen bonds.

Despite intensive experimental and theoretical studies in more than three-quarters of a century, the molecular-level origin of this peculiar isotope effect on water hydrogen bonds has been unclear.

Very recently, researchers led by Toshiki Sugimoto, Associate Professor at the Institute for Molecular Science, have tackled the longstanding mystery: how do more expanded D2O aggregates form stronger hydrogen bonds than H2O aggregates, in contrast to the hydrogen-bonded systems composed of bulky constituent molecules?

By means of isotope selective measurements on sublimation of isotope-mixed ice with various H/D isotopic compositions, the researchers have made a new discovery to unravel the mystery; the isotope effect on the strength of hydrogen bonds are governed by two deuteration effects: (1) the bond-strengthening effect derived from zero-point energy of hindered rotational motion, and (2) the bond-weakening (and elongating) effect derived from quantum anharmonic coupling between inter- and intramolecular modes.

The most important concept is that the deuteration effect (1) derived from rotational motion plays crucial roles in the bond breaking process of extremely small and light molecules. In the case of water aggregates, huge isotopic difference in the zero-point energy of hindered rotation brings out a peculiar nature of the bond strengthening effect (1) overwhelming over the bond-weakening effect (2), leading to the unique isotope effect: deuterated water molecules form longer but stronger hydrogen bonds than hydrogenated water molecules.

In contrast, in the case of other typical hydrogen-bonded systems composed of larger and heavier constituent molecules, such as oxalic acid dihydrate, benzoic acid, succinic acid, and cyclohexane/Rh(111), the isotopic differences in the zero-point energy of hindered rotation are negligibly small. Therefore, only the bond-weakening effect (2) is predominant in the isotope effect on their binding energy, resulting in the longer and weaker hydrogen bonds in deuterated systems than hydrogenated systems.

Thus, the isotopic differences in the strength of hydrogen bonds are determined by a delicate balance between the competing two deuteration effects (1) and (2), while those in hydrogen-bond length, i.e. geometrical isotope effect, are basically dominated by the deuteration effect (2). "These results and concepts provide a new basis for our fundamental understanding of the highly quantum water hydrogen bonds," says Sugimoto.

Media Contact

Toshiki Sugimoto
toshiki-sugimoto@ims.ac.jp
81-564-557-287

http://www.nins.jp/english/ 

Toshiki Sugimoto | EurekAlert!
Further information:
http://dx.doi.org/10.1103/PhysRevMaterials.3.112001

More articles from Life Sciences:

nachricht Structual color barcode micromotors for multiplex biosensing
21.01.2020 | Science China Press

nachricht Cyanobacteria in water and on land identified as source of methane
21.01.2020 | Forschungsverbund Berlin

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A new look at 'strange metals'

For years, a new synthesis method has been developed at TU Wien (Vienna) to unlock the secrets of "strange metals". Now a breakthrough has been achieved. The results have been published in "Science".

Superconductors allow electrical current to flow without any resistance - but only below a certain critical temperature. Many materials have to be cooled down...

Im Focus: Programmable nests for cells

KIT researchers develop novel composites of DNA, silica particles, and carbon nanotubes -- Properties can be tailored to various applications

Using DNA, smallest silica particles, and carbon nanotubes, researchers of Karlsruhe Institute of Technology (KIT) developed novel programmable materials....

Im Focus: Miniature double glazing: Material developed which is heat-insulating and heat-conducting at the same time

Styrofoam or copper - both materials have very different properties with regard to their ability to conduct heat. Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz and the University of Bayreuth have now jointly developed and characterized a novel, extremely thin and transparent material that has different thermal conduction properties depending on the direction. While it can conduct heat extremely well in one direction, it shows good thermal insulation in the other direction.

Thermal insulation and thermal conduction play a crucial role in our everyday lives - from computer processors, where it is important to dissipate heat as...

Im Focus: Fraunhofer IAF establishes an application laboratory for quantum sensors

In order to advance the transfer of research developments from the field of quantum sensor technology into industrial applications, an application laboratory is being established at Fraunhofer IAF. This will enable interested companies and especially regional SMEs and start-ups to evaluate the innovation potential of quantum sensors for their specific requirements. Both the state of Baden-Württemberg and the Fraunhofer-Gesellschaft are supporting the four-year project with one million euros each.

The application laboratory is being set up as part of the Fraunhofer lighthouse project »QMag«, short for quantum magnetometry. In this project, researchers...

Im Focus: How Cells Assemble Their Skeleton

Researchers study the formation of microtubules

Microtubules, filamentous structures within the cell, are required for many important processes, including cell division and intracellular transport. A...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

„Advanced Battery Power“- Conference, Contributions are welcome!

07.01.2020 | Event News

 
Latest News

A new look at 'strange metals'

21.01.2020 | Materials Sciences

Body's natural signal carriers can help melanoma spread

21.01.2020 | Health and Medicine

Structual color barcode micromotors for multiplex biosensing

21.01.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>