They manage for the first time to modify the bonds between the atoms of a molecule

An international team of scientists has achieved, for the first time, change the bonds between atoms of an individual molecule with electrical impulses. The observation that earned him the cover of the magazine ‘Science’, represents an unprecedented mastery of the world of the smallest and opens a new path for the development of sophisticated technologies nanomachines that could be used for multiple applications: from helping to create new materials to identifying tumor cells in the body.

“What motivates us is to change the books of chemistry”, explains Diego Peña, co-author of the study at the Singular Center for Research in Biological Chemistry and Molecular Materials (CiQUS) of the University of Santiago. -de-Compostelle. This center collaborated with international researchers, including IBM Research in Zurich (Switzerland), to carry out the project.

In molecules, the atoms are linked by bonds forming a three-dimensional structure of nanometer size. Molecules with the same number and type of atoms can present their bonds in different ways, which means that their atoms are connected in different ways. These compounds are called structural isomers and they bring extraordinary variability to the molecular world.

Diego Peña, CiQUS researcher


Now, scientists have found a method that allows one structural isomer to transform into another, reconnecting their bonds at will based on an external stimulus. To achieve this, they applied different voltages with the tip of a microscope scanning probe (STM) on a molecule formed of four carbon rings, inducing very precise modifications of the structure of these rings.

“Since the 19th century, chemists have been trying to modify the connectivity between atoms in molecules to obtain new functionalities,” explains Peña. “The novelty is that now we can do it extremely precisely and on individual molecules, as if we had nanometer tweezers the size of the molecules,” he explains.

Plus, researchers can do it over and over again, like playing microscopic Lego. “Not only do we control the links that form, but we also do so reversibly, we can switch between the different structures repeatedly,” explains Leo Gross, a researcher at IBM and also a signatory of the study. “We’ve done it several times, it works on demand. It’s like having a molecular switch“, confirms Pena.

Scientist Leo Gross stands next to a scanning tunneling microscope in the IBM research laboratory in Zurich


The IBM researcher believes that the selective and reversible formation of bonds can promote the creation of new molecular motors with more complex functions and tasks. They are nanomachines that can perform a certain task in response to an external stimulus. They could be useful as chemical catalysts or for carry drugs in the blood of a patient. Without going any further, our own body is home to a large number of molecular machines with functions as vital as DNA replication.

Designing artificial machines and synthesizing them in the laboratory is a very complex task, for which Jean Pierre Sauvage, J. Fraser Stoddart and Ben L. Feringa won the Nobel Prize in 2016. The ability to create and break bonds within same molecule means deliberate work. control of its structure which, in turn, forms the basis of molecular machinery. “By controlling the connectivity between atoms, we can tackle the fabrication of more complex designs,” says Peña.

science fiction

However, the researcher hesitates to imagine what these molecular machines could be used for. “What is really important in this study is fundamental research, the mastery of molecules and the advancement of knowledge. We must not create exaggerated expectations because it is not possible to predict exactly what the purpose of what we are doing will be. It’s like the laser, when it was invented, we didn’t know what we were going to do with it,” Peña reflects. “Maybe one day they can be introduced into the body to identify tumor cells and eliminate them before a tumor develops, but for now it’s science fiction and maybe it will never happen,” he warns.

The researchers plan to continue to advance this knowledge, for now basic science, essential for these dream applications to be found one day. Among their next steps, they are considering the possibility of the reactions being triggered by light or by transferring electrons between different parts of the same molecule, instead of through the tip of an STM microscope. One more step in the history of chemistry.

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