Braided molecules help scientists tie the knot

David Leigh’s group at the University of Manchester, UK, has tied the tightest molecular knot to date, comprising three molecular strands plaited together to create a circular triple helix, a loop with eight crossings.

The knot was tied using existing self-assembly techniques to weave the ligand strands around four octahedral iron(II) ions which fix the eight crossing points. The strands are joined up to close the loop using a transition metal catalyst, and the ions can then be removed.

Leigh’s team has a long track record producing interlocking molecular structures, including a knot shaped like a Star of David and a trefoil knot that can act as a catalyst. This latest knot is the most complex regular woven molecule ever made.