Formation of a [2]pseudorotaxane based on a pillar[5]arene and a rigid guest in solution and in the solid state

A pillar[5]arene with mono(ethylene oxide) groups could form a highly stable inclusion complex with a rigid guest both in solution and in the solid state. The association constant of this inclusion complex was determined to be (3.3 ± 0.41) × 10⁴ M⁻¹ in acetonitrile.

Efficient syntheses of pillar[6]arene-based hetero[4]rotaxanes using a cooperative capture strategy

While one pillar[6]arene, nestling between two cucurbit[6]urils in a hetero[4]rotaxane, is conformationally mobile in solution, it adopts the energetically most favourable conformation with local C_3V symmetry in the solid state.

Mechanized silica nanoparticles based on pillar[5]arenes for on-command cargo release

Mechanized silica nanoparticles, equipped with pillar[5]arene-[2]pseudorotaxane nanovalves, operate in biological media to trap cargos within their nanopores, but release them when the pH is lowered or a competitive binding agent is added. Although cargo size plays an important role in cargo loading, cargo charge-type does not appear to have any significant influence on the amount of cargo loading or its release. These findings open up the possibility of using pillar[n]arene and its derivatives for the formation of robust and dynamic nanosystems that are capable of performing useful functions.