Chemists Just Rearranged Atomic Bonds in a Single Molecule for the First Time
Chemists Just Rearranged Atomic Bonds in a Single Molecule for the First Time:
Chemical engineering has taken a step forward, with researchers from the University of Santiago de Compostela in Spain, the University of Regensburg in Germany, and IBM Research Europe forcing a single molecule to undergo a series of transformations with a tiny nudge of voltage.
Ordinarily, chemists gain precision over reactions by tweaking parameters such as the pH, adding or removing available proton donors to manage the way molecules might share or swap electrons to form their bonds.
"By these means, however, the reaction conditions are altered to such a degree that the basic mechanisms governing selectivity often remain elusive," the researchers note in their report, published in the journal Science.
In other words, the complexity of forces at work pushing and pulling across a large organic molecule can make it hard to get a precise measure on what's occurring at each and every bond.
The team started with a substance called 5,6,11,12-tetrachlorotetracene (with the formula C18H8Cl4) – a carbon-based molecule that looks like a row of four honeycomb cells flanked by four chlorine atoms hovering around like hungry bees.
Sticking a thin layer of the material to a cold, salt-crusted piece of copper, the researchers drove the chlorine-bees away, leaving a handful of excitable carbon atoms holding onto unpaired electrons in a range of related structures.
Two of those electrons in some of the structures happily reconnected with each other, reconfiguring the molecule's general honeycomb shape. The second pair were also keen to pair up not just with each other, but with any other available electron that might buzz their way.
Chemists Change the Bonds Between Atoms in a Single Molecule for the First Time
Chemists change the bonds between atoms in a single molecule for the first time:
A team of researchers from IBM Research Europe, Universidade de Santiago de Compostela and the University of Regensburg has changed the bonds between the atoms in a single molecule for the first time. In their paper published in the journal Science, the group describes their method and possible uses for it. Igor Alabugin and Chaowei Hu, have published a Perspective piece in the same journal issue outlining the work done by the team.
The current method for creating complex molecules or molecular devices, as Alagugin and Chaowei note, is generally quite challenging—they liken it to dumping a box of Legos in a washing machine and hoping that some useful connections are made. In this new effort, the research team has made such work considerably easier by using a scanning tunneling microscope (STM) to break the bonds in a molecule and then to customize the molecule by creating new bonds—a chemistry first.
The work by the team involved placing a sample material into a scanning tunneling microscope and then using a very tiny amount of electricity to break specific bonds. More specifically, they began by pulling four chlorine atoms from the core of a tetracyclic to use as their starting molecule. They then moved the tip of the STM to a C-CI [sic - they mean C-Cl] bond and then broke the bond with a jolt of electricity. Doing so to the other C-CI and C-C pairs resulted in the formation of a diradical, which left six electrons free for use in forming other bonds. In one test of creating a new molecule, the team then used the free electrons (and a dose of high voltage) to form diagonal C-C bonds, resulting in the creation of a bent alkyne. In another example, they applied a dose of low voltage to create a cyclobutadiene ring.
The researchers note that their work was made possible by the development of ultrahigh precision tunneling technology developed by a team headed by Gerd Binnig and Heinrich Rohrer, both with IBM's laboratory in Zurich. They suggest their technique could be used to better understand redox chemistry and to create new kinds of molecules.
Journal Reference:
Florian Albrecht, Shadi Fatayer, Iago Pozo, et al., Selectivity in single-molecule reactions by tip-induced redox chemistry, Science, 377, 2022. DOI: 10.1126/science.abo6471
(Score: 2) by Rosco P. Coltrane on Tuesday July 19 2022, @10:47PM
Just wait till they hear about hydrolysis.
(Score: 2) by corey on Thursday July 21 2022, @01:01AM
Cool. One step closer to molecular printers!