Chemists tie tiniest record-holding knot

Chemists tie tiniest record-holding knot


Researchers in Manchester in the UK built a knot from a strand of atoms which curls around in a triple loop and crosses itself eight times. Made from 192 atoms linked in a chain, the knot is only two millionths of a millimetre wide – around 200,000 times thinner than a human hair.

The construction of the knot is more than a demonstration of the precise control with which chemists can now manipulate objects on the atomic scale. In learning how to weave with strands of atoms, scientists hope to make possible a whole new world of materials.

The tightness of a knot is defined by the distance between points where the rope, string – or chain of atoms, in this case – cross each other. For the Manchester group’s circular triple helix, each crossing point is a mere 24 atoms apart.

The new knot, designed and built with research associate Jonathan Danon and others, assembles itself from a solution that contains four strands of carbon, nitrogen and oxygen atoms. When mixed with iron and chloride ions in a heated solvent, the atomic threads form the basic shape of the knot in about a day. In a second step, the ends of each strand are fused together to make a continuous loop of atoms. The metal and chloride ions are then washed away, leaving only the knot behind.

These knots can be used for various purposes after enough research. The scientists had made another knot in 2012, known as pentafoil. Pentafoil is known to have good catalytic properties for chemical reactions. Similarly, the recently developed tiniest knot can be explored further for different applications.