Self-assembly of the smallest and tightest molecular trefoil knot.

Molecular knots, whose synthesis 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 knotted structure. Here we report the synthesis by self-assembly of molecular trefoil metallaknot with formula [Au 6 {1,2-C 6 H 4 (OCH 2 CC) 2 } 3 {Ph 2 P(CH 2 ) 4 PPh 2 } 3 ], Au 6 , from three units of each of the components 1,2-C 6 H 4 (OCH 2 CCAu) 2 and Ph 2 P(CH 2 ) 4 PPh 2 . Structure determination by X-ray diffraction revealed that the chiral trefoil knot contains only 54 atoms in the backbone, so that Au 6 is the smallest and tightest molecular trefoil knot known to date.