Protons, as positively charged hydrogen ions, move very rapidly in water from one water molecule to the next, which is why the conductivity of water is relatively high.
The principle of proton conduction in water has been known for 200 years and is named the Grotthuss mechanism after its discoverer, Theodor Grotthuss. It is based on the assumption that it is not that a single specific proton moving from one molecule to another; instead, there is cleavage of bonds. One proton docks onto a molecule and this causes another proton to leave that molecule and bind to another molecule somewhere else.
This proton exchange mechanism has been compared to a 'bucket line' to explain the rapid diffusion of the individual protons. However, this concept oversimplifies the situation and belies the complexity of the structure of water. Researchers from Zurich and Mainz have now been able to analyze the mechanism in more detail using theoretical calculations and have shown that the currently accepted picture of proton diffusion may need to be revised.
"The simulation shows that the crossover from one water molecule to the next occurs more quickly than previously thought and then there is a rest period until the next crossover," said Professor Thomas D. Kühne of the Institute of Physical Chemistry at Johannes Gutenberg University Mainz (JGU), describing the results. These were published online on July 18, 2013 in the journal Proceedings of the National Academy of Sciences.
"We show that the diffusion of protons and hydroxide ions occurs during periods of intense activity involving concerted proton hopping, followed by periods of rest," wrote primary author Ali A. Hassanali of the Swiss Federal Institute of Technology Zurich in the publication. In the model of proton diffusion that researchers have now developed, the hydrogen bridge network is equivalent to an aggregation of closed rings. The resulting proton chains serve as a 'road' in the hydrogen bridge network that make possible long proton jumps across multiple hydrogen bridge bond formations. "The water molecules 'dance' around each other until they achieve an energetically favorable status. Only then will a proton hop along the 'road' to another molecule," explained Kühne. As a result, there is temporary formation of protonated water molecules with three protons.
In addition to the relevance of proton transfer in aqueous systems, the results may also be applicable to important biological systems such as enzymes and macromolecules.
Petra Giegerich | idw
New therapeutic approach to combat African sleeping sickness
20.02.2019 | Johannes Gutenberg-Universität Mainz
'Butterfly-shaped' palladium subnano cluster built in 3-D
20.02.2019 | Institute of Industrial Science, The University of Tokyo
Up to now, OLEDs have been used exclusively as a novel lighting technology for use in luminaires and lamps. However, flexible organic technology can offer much more: as an active lighting surface, it can be combined with a wide variety of materials, not just to modify but to revolutionize the functionality and design of countless existing products. To exemplify this, the Fraunhofer FEP together with the company EMDE development of light GmbH will be presenting hybrid flexible OLEDs integrated into textile designs within the EU-funded project PI-SCALE for the first time at LOPEC (March 19-21, 2019 in Munich, Germany) as examples of some of the many possible applications.
The Fraunhofer FEP, a provider of research and development services in the field of organic electronics, has long been involved in the development of...
For the first time, an international team of scientists based in Regensburg, Germany, has recorded the orbitals of single molecules in different charge states in a novel type of microscopy. The research findings are published under the title “Mapping orbital changes upon electron transfer with tunneling microscopy on insulators” in the prestigious journal “Nature”.
The building blocks of matter surrounding us are atoms and molecules. The properties of that matter, however, are often not set by these building blocks...
Scientists at the University of Konstanz identify fierce competition between the human immune system and bacterial pathogens
Cell biologists from the University of Konstanz shed light on a recent evolutionary process in the human immune system and publish their findings in the...
Laser physicists have taken snapshots of carbon molecules C₆₀ showing how they transform in intense infrared light
When carbon molecules C₆₀ are exposed to an intense infrared light, they change their ball-like structure to a more elongated version. This has now been...
The so-called Abelian sandpile model has been studied by scientists for more than 30 years to better understand a physical phenomenon called self-organized...
11.02.2019 | Event News
30.01.2019 | Event News
16.01.2019 | Event News
20.02.2019 | Life Sciences
20.02.2019 | Medical Engineering
20.02.2019 | Power and Electrical Engineering