An international team of chemists has set a new world record for tying the world’s smallest knot, which they say consists of only 54 atoms.
Remarkably, researchers involved with the achievement say it happened by accident, and are unable to account for how it occurred.
Chemists Zhiwen Li, Jingjing Zhang, Gao Li with the Chinese Academy of Sciences’ Dalian Institute of Chemical Physics, and research colleague Richard J. Puddephatt with the University of Western Ontario, Canada, were attempting an entirely different process in the lab when the record breaking discovery was made.
Their achievement is described in a study that recently appeared in the journal Nature Communications.
Tying the World’s Smallest Knot
While attempting to create metal acetylides, a variety of alkynes used in research that involves organic reactions, the group says they unintentionally succeeded at tying a minuscule knot comprised of a small string of only 54 atoms.
The knot was created while the team was attempting to connect carbon structures to gold acetylides, a process relied on in the production of creating basic chains of gold that chemists call caternames.
However, one of the reactions they performed created a chain that tied itself into a chiral trefoil knot similar to those bakers use when making pretzels.
“Molecular knots, whose synthesis presents many challenges, can play important roles in protein structure and function as well as in useful molecular materials, whose properties depend on the size of the knotted structure,” the researchers write in their recent paper.
Significantly, the molecular knot the research team unexpectedly created had a backbone crossing ratio (BCR), a measurement of the strength of a knot, of 23. By comparison, most organic knots typically have BCRs of between 27 and 33.
The research team writes that X-ray diffraction measurements confirmed that the chiral trefoil knot contains just 54 atoms in its BCR, making it “the smallest and tightest molecular trefoil knot known to date.”
A Record Breaker that Remains a Mystery
In 2020, similar experiments resulted in the production of a 69-atom knot by another Chinese research team, although that knot had been created intentionally with help from special knot-tying techniques used to entwine tiny strands into knots.
Given that the new record-breaking knot was created entirely by accident, the researchers are unsure of exactly what processes allowed for its creation, nor are they sure whether similar processes could be used to create even tinier knots under lab conditions.
Although the achievement represents a new record, the research team says there could be practical benefits to such processes too. For instance, chemists may be able to build on their observations to help scientists understand how proteins like RNA and DNA form similar knots under entirely natural conditions.
Extremely small knot-making techniques could also help facilitate the creation of new varieties of substances that include plastics with novel properties.
The team’s new paper, “Self-assembly of the smallest and tightest molecular trefoil knot,” was published in Nature Communications on January 2.