Chemists tie the tightest knot ever, made up of just 54 atoms

Chemists tie the tightest knot ever, made up of just 54 atoms

Scientists have accidentally tied the smallest and tightest knot ever, eclipsing the first place in the Guinness Book of World Records.

This fascinating microscopic tangle contains just 54 atoms that twist around three times to form an entangled ring called a tangle “trilobite” Knots, with no loose ends.

The three-leaf clover shape is the simplest non-trivial knot, and is fundamental to mathematical knot theory.

Chemists in China 2020 training A chain of 69 atoms that intersect three times to form a trilobite. Now, researchers at the University of Western Ontario in Canada have collaborated with the Chinese Academy of Sciences and broken this record.

As the ratio of atoms to “back pass” decreases, the strength of the molecular knot increases. The node created in 2020 has Backbone crossing ratio (BCR) From 23.

The current node has a BCR of 18.

Smallest knot
A diagram showing the structure of the smallest node. (Li et al., Nature Communications2024)

Most organic molecular complexes have a BCR between 27 and 33. While experts are unsure how small or tight knots they can continue to make single knots, quantum chemical calculations Suggest The most stable trilobite structure is about 50 molecules long, which means we are slowly approaching the theoretical limit.

This latest breakthrough brings experts closer than ever to the microscopic knots that naturally form in the DNA, RNA, and various proteins in our bodies. Furthermore, understanding how the latest forms of knots can help scientists build better plastics and polymers.

“Molecular knots, whose structure 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 complex structure.” He explains Research team.

Like many scientific discoveries, this one was a happy accident. Chemist Richard Budivat Tell Alex Wilkins in new world How did this event happen by chance?

Puddephatt and his colleagues were working on the creation Mineral acetides In the laboratory, they are alkynes – a type of hydrocarbon – with the hydrogen removed from their end. This final product is very useful because it can help scientists perform organic chemical reactions.

When linking the gold acetylide to another carbon structure called a diphosphine bond, the team unexpectedly created a three-lobed knot instead of a gold chain, or catenane.

Since 1989, chemists have been trying to tie up molecular knots Orientation of spiral chains to the desired structure with metal ions.

In 2020, for example, chemists tied the tightest trilobite knot at the time using metal atoms to “Fold and interlock“Molecular tape. When these metal atoms are removed at the end of the process, the knot cannot be untied.

The newest gold ‘metal knot’ is different because it assembles itself.

“It’s a very complex system, and frankly, we don’t know how it happens,” says Budivat, who works at the University of Western Ontario. Tell new world.

He and his colleagues hope that their complex will provide “a strong incentive to pursue similar, but hopefully more robust, structures via self-assembly” in the future.

The study was published in Nature Communications.

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