C22H46: The smallest open 31-knotted alkane by computer-aided design

The program MolKnot [Chem. Phys. Lett. 433 (2007) 422–426] has been used in order to detect the smallest ever-reported alkane configured to an open-knotted shape with three crossings (31). High level ab initio calculations support our findings that 22 carbon atoms are enough to create a knotted polyethylene strand with open ends. These tight open molecular knots exhibit unusually distorted geometric characteristics as multiple extended CC bonds (maximum bond length ∼1.70 Å) and several large CCˆC bond angles (maximum bond angle ∼145°). The energy decomposition shows that the strain mainly affects the valence angles of the entangled structure. We observed that this 22-knotted carbon atoms’ region remained almost intact as a part of alkanes with longer chain lengths.