Pentafoil knot structure. Animation of a molecular structure forming a pentafoil knot, a type of molecular knot with five crossing points. Atoms are represented as spheres. Examples of molecular knots include forms of DNA and proteins. Small molecular knots may have applications in nanotechnology. In 2011, a pentafoil knot of 160 atoms was reported to have been synthesised, consisting of five aldehydes and five amines surrounding five metal cations (yellow), with a chloride anion at the centre of the knot structure. During the animation, the structure is shown in both space-filled form and in ball-and-stick form.