The interactions of chemical mirror images

October 11, 2018, Ruhr-Universitaet-Bochum
Christian Merten works at the Bochum Department of Organic Chemistry II and is a member of the Cluster of Excellence Resolv. Credit: RUB, Kramer

Chemists from Ruhr-Universität Bochum are hoping to find out how strongly the mirror-image chemical molecules – called chiral compounds – interact with their interaction partners. They are concentrating on halogen bonds that molecules with a bromine or iodine atom can form. These interactions are currently being investigated in many areas of chemistry as design elements for functional molecules, such as modern catalysts and new materials or pharmaceutically active compounds. The work of the researchers led by Dr. Christian Merten from the Department of Organic Chemistry II is being funded by the Boehringer Ingelheim Foundation as part of the "Plus 3" perspectives programme with around 760,000 euros for three years. The project starts in November 2018.

Chemical mirror images can have very different effects

Many , such as amino acids and sugars, exist in two mirror-imaged spatial arrangements, but usually only one of them occurs in nature. "Biologically, the effect of can be very different," says Christian Merten, a member of the Cluster of Excellence Ruhr Explores Solvation, Resolv for short. "This is mainly due to the fact that the mirror-image forms interact with biomolecules such as enzymes in different ways."

Chemists are therefore pursuing the goal of specifically producing one of the mirror-image forms and being able to precisely understand and predict its interactions with other molecules. The project "Stereochemical communication as probe for halogen bonding interactions" by the Bochum-based researchers is mainly dedicated to the second aspect, the strength of the interaction.

Halogen bonds are difficult to study

A halogen bond forms between the positively polarised end of a carbon-bromine or carbon-iodine bond of a molecule and an interaction partner. The energy of this weak interaction is particularly difficult to quantify. "The interaction energies of model substances, which we can describe well with modern theoretical methods, are difficult to determine experimentally because the substances are often gaseous," explains Christian Merten. "But the model substances that we can easily handle experimentally are usually much too large and complex for today's most accurate computer models." In addition, halogen bonding interactions in solution often compete with other intermolecular interactions, such as the interactions with solvents.

The team hopes to circumvent this problem with a new experimental setup. The researchers are replacing the solvent with noble gases that are liquefied under pressure and at low temperatures. They are inert and cannot form any disturbing interactions.

Predictions as the goal

For a number of model systems, chemists want to find out whether halogen bonds between chiral molecules have different energies. They are mainly interested in what happens when two different chiral substances interact with each other. The decisive factor here is which mirror images meet. "This is like two hands shaking each other," Christian Merten explains. "The handshake works optimally with two right or two left hands; with one right and one left hand, it does not." The two types of interaction differ in the energy they contain, depending on how well the molecules fit together. The scientists want to measure how big the difference is.

"Our goal is to one day be able to predict which structural elements are needed to make this process of chiral recognition as efficient as possible," says Merten.

Explore further: Unique method creates correct mirror image of molecule

Related Stories

Unique method creates correct mirror image of molecule

May 22, 2013

Many molecules have a right and a left form, just like shoes. In pharmaceuticals, it is important that the correct form of the molecule is used. Researchers at the University of Gothenburg, Sweden, have been able to produce ...

Machine learning offers new way of designing chiral crystals

April 10, 2018

Engineers and chemists at Hiroshima University successfully used the technology underlying facial recognition to design chiral crystals. This is the first study reporting the use of this technology, called logistic regression ...

Chiral crabs

September 22, 2017

Sander Wezenberg, and PhD students Thomas van Leeuwen and Kaja Sitkowska, from the University of Groningen in the Netherlands, spoke to us about their work in chirality and molecular motors, and the seaside scene on the cover ...

Recommended for you

Meteorite source in asteroid belt not a single debris field

February 17, 2019

A new study published online in Meteoritics and Planetary Science finds that our most common meteorites, those known as L chondrites, come from at least two different debris fields in the asteroid belt. The belt contains ...

Diagnosing 'art acne' in Georgia O'Keeffe's paintings

February 17, 2019

Even Georgia O'Keeffe noticed the pin-sized blisters bubbling on the surface of her paintings. For decades, conservationists and scholars assumed these tiny protrusions were grains of sand, kicked up from the New Mexico desert ...

Archaeologists discover Incan tomb in Peru

February 16, 2019

Peruvian archaeologists discovered an Incan tomb in the north of the country where an elite member of the pre-Columbian empire was buried, one of the investigators announced Friday.

Where is the universe hiding its missing mass?

February 15, 2019

Astronomers have spent decades looking for something that sounds like it would be hard to miss: about a third of the "normal" matter in the Universe. New results from NASA's Chandra X-ray Observatory may have helped them ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.