Just a single foreign atom located in the vicinity of a molecule can change spatial arrangement of its atoms. In a spectacular experiment, an international team of researchers was able to change persistently positions of the nuclei of hydrogen atoms in a porphycene molecule by approaching a single copper atom to the molecule.
A subatomic bit formed by two protons tunnelling inside a simple organic molecule can be switched by approaching a single copper atom to the molecule. A spectacular experiment to demonstrate the phenomenon was carried out by a team of researchers from the Fritz-Haber-Institute of the Max-Planck-Gesellschaft (FHI) in Berlin, the University of Liverpool (UL) and the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) in Warsaw. The experiment was reported in a paper published in "Nature Chemistry", one of the most prestigious chemical journals.
In the study the researchers made use of specific properties of the porphycene molecule. Porphycene (C20H14N4) is a porphyrin derivative. Chemical compounds belonging to this group occur naturally. They are found, e.g., in human blood, where they are involved in reactions related to oxygen transport. Their molecules have a form of planar carbon rings with hydrogen atoms outside and four nitrogen atoms inside, located in the corners of a tetragon.
In the centre of a porphycene molecule, in an empty space surrounded by nitrogen atoms, there are two protons (i.e., nuclei of hydrogen atoms) that can move between the nitrogens. It is interesting that both protons are always displaced together. The research carried out for over a decade by Prof. Jacek Waluk's team (IPC PAS) suggests that the movement of protons is not simply a displacement in space. The protons change their positions due to quantum tunnelling effect: making use of the uncertainty principle they just disappear at one place and reappear in another.
In the Berlin FHI labor
|Contact: Jacek Waluk|
Institute of Physical Chemistry of the Polish Academy of Sciences