A collaboration between Durham University and the University of York scientists twisted molecules beyond their breaking point in order to test current knowledge of chemical bonds. The researchers investigated how far an aromatic ring's chemical bonding may be twisted before its aromatic bonding breaks.
To do this, SciTech Daily reports that the team created overloaded aromatic rings using tropylium instead of benzene since the former shares electrons around a ring of seven carbon atoms.
A molecule model with reflection on a dark surrounding.
Chemical Bonds in Aromatic Ring
The structure, stability, and function of compounds, such as pharmaceuticals and polymers, are all dependent on chemical bonding in aromatic molecules, according to the University of York's press release.
Some of molecule's electrons must easily flow around a ring in its structure for it to be called aromatic. Benzene is a classic example, wherein six of its electrons are shared among six carbon atoms in a ring.
Aromatic rings favor flat surfaces, but a recent study has demonstrated that this is not always the case. Aromatic rings twist when they are squeezed.
The team of researchers, led by Dr. Paul McGonigal, has devised a sophisticated solution to this basic challenge. They made overloaded aromatic rings and used tropylium instead of benzene because compared to the latter, the former shares electrons around a ring of seven carbon atoms.
Each of these carbon atoms may be functionalized, and the researchers were able to squeeze more groups around the aromatic ring's edge by employing seven attachment sites rather than six.
They discovered that mild degrees of overcrowding caused the ring to twist but not destroy its aromatic bonding. Surprisingly, the molecule could be bent by 45 degrees from one end to the other.
Dr. Paul McGonigal remarked that the strain and aromatic bonding are finely controlled in these overloaded molecules, creating a balance that ultimately determines the structure, qualities, and potential uses of the material.
The scientists twisted the ring further by adding progressively bigger groups around the edge, finally causing the aromatic bonding to disintegrate. The electrons no longer circle the seven carbon atoms, and the ring pinches over the center to produce two smaller flat rings.
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Reflections on The Findings of the Study
Researchers discovered a balancing point at which the ring alternates between the aromatic structure and the two smaller rings, Phys.org reported. In this study, one molecule spends 90% of its time as the squeezed structure and 10% of its time as a bigger aromatic ring.
Dr. McGonigal reflected on the results and realized that the structure, properties, and even possible applications of a material are determined by this balance. He noted that the control of twisting materials at the molecular level is unprecedented. Not only was an aromatic molecule can be twisted up to its maximum strain but it can also tolerate what happens when pushed beyond the limit.
Indeed, the reversible pinching and reopening of an aromatic ring are notable for their powerful stabilizing force. The findings of the study, titled "Rupturing Aromaticity by Periphery Overcrowding," is published in the journal Nature Chemistry.
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