Researchers from the University of Cambridge and the University of Manchester have woven chains of carbon, hydrogen, oxygen, and nitrogen atoms together in a triple braid - forming the most complex molecular knot ever made. Learning how to tie such knots could one day help researchers weave molecular fabrics with a wide array of properties. Sticky metal ions hold the atom building blocks in the correct position, and a single chloride ion sitting in the middle of the structure anchors it all together. Then, a chemical catalyst links the building blocks, forming the completed knot. The new knot is the tightest ever created, the researchers say, with just 24 atoms between each crossing point.