Supramolecular approach for solid state Brownian rotators

Artificial molecular rotators were designed in an attempt to achieve unidirectional molecular rotation. Supramolecular assemblies of cations and crown ethers in the solid state were shown to form rotator structures, diverse in their rotational symmetry and frequency. The counter cation of [Ni(dmit)2]− anion, bearing one S = 1/2 spin, was used to couple molecular rotation to magnetic properties. Random rotation of [18]crown-6 molecules was first observed in the Cs+2([18]crown-6)3 supramolecule, where the rotational freedom of [18]crown-6 rotators was evidently coupled to the magnetic properties of [Ni(dmit)2]−π-dimer. In other cases, dual rotary motions of anilinium([18]crown-6) and rotator–stator assemblies of (adamantylammonium)(dibenzo[18]crown-6) were investigated as a means to control rotational symmetries and frequencies in the solid state. The supramolecular approach for construction of molecular rotator–stator assemblies in the solid state is a convenient approach to the design of molecular rotary functionality in [Ni(dmit)2]− salts.