Equilibrium Shift in Solution: Molecular Shape Recognition and Precipitation of a Synthetic Double Helix Using Helicene‐Grafted Silica Nanoparticles

Chiral silica nanoparticles (70 nm) grafted with ( P )‐helicene recognized the molecular shape of double helix and random coil ( P )‐ethynylhelicene oligomers in solution. A mixture of the ( P )‐nanoparticles and double helix precipitated much faster than a mixture of the ( P )‐nanoparticles and random coil, and the precipitate contained only the double helix. The mixture of the ( P )‐nanoparticles and ( P )‐ethynylhelicene pentamer reversibly dispersed in trifluoromethylbenzene upon heating at 70 °C and precipitated upon cooling at 25 °C. When a 10:90 equilibrium mixture of the double helix and random coil in solution was treated with the ( P )‐nanoparticles, the double helix was precipitated in 53 % yield and was accompanied by equilibrium shift.