Featured Research

from universities, journals, and other organizations

Chemical chameleon tamed: Researchers give floppy molecule a structure through solvent effects

Date:
March 14, 2013
Source:
Ruhr-Universitaet-Bochum
Summary:
How you get the chameleon of the molecules to settle on a particular "look" has been discovered by chemists in Germany. The molecule CH5+ is normally not to be described by a single rigid structure, but is dynamically flexible. By means of computer simulations, the team showed that CH5+ takes on a particular structure once you attach hydrogen molecules.

Giving the “chameleon” molecule structure: Depending on how many H2 solvent molecules (blue) attach to the CH5+ molecule, the area in which the hydrogen atoms of the CH5+ molecule move changes (red). Its structure is thus partially “frozen”. The areas represent quantum mechanical probability densities at a temperature of 20 Kelvin.
Credit: Copyright A. Witt, S. Ivanov, D. Marx

How you get the chameleon of the molecules to settle on a particular "look" has been discovered by RUB chemists led by Professor Dominik Marx. The molecule CH5+ is normally not to be described by a single rigid structure, but is dynamically flexible. By means of computer simulations, the team from the Centre for Theoretical Chemistry showed that CH5+ takes on a particular structure once you attach hydrogen molecules.

"In this way, we have taken an important step towards understanding experimental vibrational spectra in the future," says Dominik Marx. The researchers report in the journal Physical Review Letters.

In the CH5+ molecule, the hydrogen atoms are permanently on the move

The superacid CH5++, also called protonated methane, occurs in outer space -- where new stars are formed. Researchers already discovered the molecule in the 1950s, but many of its features are still unknown. Unlike conventional molecules in which all the atoms have a fixed position, the five hydrogen atoms in CH5+ are constantly moving around the carbon centre. Scientists speak of "hydrogen scrambling." This dynamically flexible structure has been explained by the research groups led by Dominik Marx and Stefan Schlemmer of the University of Cologne as part of a long-term collaboration. Marx's team now wanted to know if the structure can be "frozen" under certain conditions by attaching solvent molecules -- a process called microsolvation.

Microsolvatation: addition of hydrogen molecules to CH5+ one by one

To this end, the chemists surrounded the CH5+ molecule in the virtual lab with a few hydrogen molecules (H2). Here, the result is the same as when dissolving normal ions in water: a relatively tightly bound shell of water molecules attaches to each ion in order to then transfer individual ions with several solvent molecules bound to them to the gas phase. To describe the CH5+ hydrogen complexes, classical ab initio molecular dynamics simulations are not sufficient. The reason is that "hydrogen scrambling" is based on quantum effects. Therefore Marx's group used a fully quantum mechanical method which they developed in house, known as ab initio path integral simulation. With this, the essential quantum effects can be taken into account dependent on the temperature.

Hydrogen molecules give the CH5+ molecule "structure"

The chemists carried out the simulations at a temperature of 20 Kelvin, which corresponds to -253 degrees Celsius. In the non-microsolvated form, the five hydrogen atoms in the CH5+ molecule are permanently changing positions even at such low temperatures -- and entirely due to quantum mechanical effects. If CH5+ is surrounded by hydrogen molecules, this "hydrogen scrambling" is, however, significantly effected and may even completely come to a halt: the molecule assumes a rudimentary structure. How this looks exactly depends on how many hydrogen molecules are attached to the CH5+ molecule. "What especially interests me is if superfluid helium -- like the hydrogen molecules here -- can also stop hydrogen scrambling in CH5++" says Marx. Experimental researchers use superfluid helium to measure high-resolution spectra of molecules embedded in such droplets. For CH5+ this has so far not been possible. In the superfluid phase, the helium atoms are, however, indistinguishable due to quantum statistical effects. To be able to describe this fact, the theoretical chemists at the RUB spent many years developing a new, even more complex path-integral-based simulation method that has recently also been applied to real problems.


Story Source:

The above story is based on materials provided by Ruhr-Universitaet-Bochum. Note: Materials may be edited for content and length.


Journal Reference:

  1. Alexander Witt, Sergei D. Ivanov, Dominik Marx. Microsolvation–Induced Quantum Localization in Protonated Methane. Physical Review Letters, 2013; 110 (8) DOI: 10.1103/PhysRevLett.110.083003

Cite This Page:

Ruhr-Universitaet-Bochum. "Chemical chameleon tamed: Researchers give floppy molecule a structure through solvent effects." ScienceDaily. ScienceDaily, 14 March 2013. <www.sciencedaily.com/releases/2013/03/130314085054.htm>.
Ruhr-Universitaet-Bochum. (2013, March 14). Chemical chameleon tamed: Researchers give floppy molecule a structure through solvent effects. ScienceDaily. Retrieved August 2, 2014 from www.sciencedaily.com/releases/2013/03/130314085054.htm
Ruhr-Universitaet-Bochum. "Chemical chameleon tamed: Researchers give floppy molecule a structure through solvent effects." ScienceDaily. www.sciencedaily.com/releases/2013/03/130314085054.htm (accessed August 2, 2014).

Share This




More Matter & Energy News

Saturday, August 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Tesla, Panasonic Ink Deal To Make Huge Battery 'Gigafactory'

Tesla, Panasonic Ink Deal To Make Huge Battery 'Gigafactory'

Newsy (July 31, 2014) The deal will help build a massive battery factory that Tesla says will produce 500,000 lithium batteries by 2020. Video provided by Newsy
Powered by NewsLook.com
Britain Testing Driverless Cars on Roadways

Britain Testing Driverless Cars on Roadways

AP (July 30, 2014) British officials said on Wednesday that driverless cars will be tested on roads in as many as three cities in a trial program set to begin in January. Officials said the tests will last up to three years. (July 30) Video provided by AP
Powered by NewsLook.com
7 Ways to Use Toothpaste: Howdini Hacks

7 Ways to Use Toothpaste: Howdini Hacks

Howdini (July 30, 2014) Fresh breath and clean teeth are great, but have you ever thought, "my toothpaste could be doing more". Well, it can! Lots of things! Howdini has 7 new uses for this household staple. Video provided by Howdini
Powered by NewsLook.com
Smoked: 2015 Ducati Diavel Vs 2014 Chevy Corvette Stingray Drag Race

Smoked: 2015 Ducati Diavel Vs 2014 Chevy Corvette Stingray Drag Race

Cycle World (July 30, 2014) The Bonnier Motorcycle Group presents Smoked; a three part video series. In this episode the 2015 Ducati Diavel takes on the 2014 Chevy Corvette Stingray Video provided by Cycle World
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins