Featured Research

from universities, journals, and other organizations

Detecting mirror molecules: New technique reliably tells left-handed from right-handed variant of a compound

Date:
May 22, 2013
Source:
Harvard University
Summary:
Physicists have developed a novel technique that can detect molecular variants in chemical mixtures -- greatly simplifying a process that is one of the most important, though time-consuming, processes in analytical chemistry.

Harvard physicists have developed a novel technique that can detect molecular variants in chemical mixtures -- greatly simplifying a process that is one of the most important, though time-consuming, processes in analytical chemistry.

As described in a paper in Nature, post-doctoral researcher David Patterson, Professor of Physics John Doyle and Dr. Melanie Schnell of the Center for Free-Electron Laser Science (CFEL) in Hamburg, Germany developed a system that relies on finely-tuned microwave fields to identify molecular variants apart, and to determine how much variant is in a mixture.

The ability to tell such variants apart, researchers said, is critical because many chemical compounds exist in two forms, each of which is a mirror image of the other. Such molecules are called chiral, from the ancient Greek for hand, and are often described as being either "right-handed" or "left-handed."

Knowing whether a molecule is right- or left-handed, scientists say, is important, because each type of molecule behaves differently in chemical reactions. Much of biology, for example, is predicated on the idea that amino acids are "left-handed," while sugar molecules are "right-handed."

"The 'wrong' sort of a compound can function completely differently in an organism," explains Schnell, who leads an independent Max Planck research group for structure and dynamics of molecules at CFEL. "In the best case it is just ineffective. In the worst case it is toxic."

The challenge, however, is that telling the two variants of a chiral molecule apart is no easy job.

A common way to discern between them is to shine linear polarised light through them. While one variant will turn the plane of polarisation to the left, the other will turn it to the right. The problem with that method, researchers say, is that it produces rather weak effects, and can only be used on liquid samples, and it can be difficult to use on samples that contain a mixture of many different species.

"It's an extremely common situation to have a mixture -- say a blood sample, or something from a complex chemical process -- that contains a left-handed version of some compounds and a right handed version others -- for example, left handed alanine along with right handed citric acid. Optical polarimetery really struggles with such a situation -- if there's more than about 3 compounds, it's pretty hopeless. We hope our technique will provide a tool which can produce a complete analysis of such a mixture."

In contrast, the method developed by Patterson, Doyle and Schnell, by comparison, relies on what is called the electric dipole moment of each molecule, or the way each interacts with an external electric field. As a consequence of their mirror-image construction, molecules rotate in opposite directions when certain microwave fields are applied -- and this results in a signature which tells if the molecules are left or right handed.

To measure the dipole moment of molecules, the team used microwaves.

Researchers fed a gaseous sample into a chamber, then cooled it to -226 degrees Celsius. As the cold gas interacted with a precisely-tuned microwave fieldwhich caused the molecules to spin and give off their own microwave radiation. By monitoring those emissions, researchers are able to tell whether the molecules are right- or left-handed.

The researchers tested their method using the organic compound 1,2-propanediol, and were able to reliably differentiate between the two variants, but also determine the ratio of variants in a mixture by finely-tuning the microwave frequency.

"We can soon measure mixtures of different compounds and determine the enantiomer ratios of each," explains Schnell. In a next step the researchers plan to apply the technique in a broadband spectrometer at CFEL that could then measure the ratios in other mixtures of substances.

In the longer run, the method opens the exciting perspective to develop a technique for separating variants -- a technique that, if successful, could be of great interest to a number of industries, particularly the development of new pharmaceuticals.


Story Source:

The above story is based on materials provided by Harvard University. Note: Materials may be edited for content and length.


Journal Reference:

  1. David Patterson, Melanie Schnell, John M. Doyle. Enantiomer-specific detection of chiral molecules via microwave spectroscopy. Nature, 2013; 497 (7450): 475 DOI: 10.1038/nature12150

Cite This Page:

Harvard University. "Detecting mirror molecules: New technique reliably tells left-handed from right-handed variant of a compound." ScienceDaily. ScienceDaily, 22 May 2013. <www.sciencedaily.com/releases/2013/05/130522131202.htm>.
Harvard University. (2013, May 22). Detecting mirror molecules: New technique reliably tells left-handed from right-handed variant of a compound. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2013/05/130522131202.htm
Harvard University. "Detecting mirror molecules: New technique reliably tells left-handed from right-handed variant of a compound." ScienceDaily. www.sciencedaily.com/releases/2013/05/130522131202.htm (accessed July 22, 2014).

Share This




More Matter & Energy News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Government Approves East Coast Oil Exploration

Government Approves East Coast Oil Exploration

AP (July 18, 2014) The Obama administration approved the use of sonic cannons to discover deposits under the ocean floor by shooting sound waves 100 times louder than a jet engine through waters shared by endangered whales and turtles. (July 18) Video provided by AP
Powered by NewsLook.com
Sunken German U-Boat Clearly Visible For First Time

Sunken German U-Boat Clearly Visible For First Time

Newsy (July 18, 2014) The wreckage of the German submarine U-166 has become clearly visible for the first time since it was discovered in 2001. Video provided by Newsy
Powered by NewsLook.com
Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Reuters - US Online Video (July 17, 2014) President Barak Obama stopped by at a lunch counter in Delaware before making remarks about boosting the nation's infrastructure. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com
Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

TheStreet (July 16, 2014) Oil Futures are bouncing back after tumbling below $100 a barrel for the first time since May yesterday. Jeff Grossman is the president of BRG Brokerage and trades at the NYMEX. Grossman tells TheStreet the Middle East is always a concern for oil traders. Oil prices were pushed down in recent weeks on Libya increasing its production. Supply disruptions in Iraq fading also contributed to prices falling. News from China's economic front showing a growth for the second quarter also calmed fears on its slowdown. Jeff Grossman talks to TheStreet's Susannah Lee on this and more on the Energy Department's Energy Information Administration (EIA) report. Video provided by TheStreet
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