A ring of rotaxanes: studies of a large paramagnetic assembly in solution

Abstract

Here we report the synthesis and structural characterization of four [7]rotaxanes formed by coordinating hybrid inorganic-organic [2]rotaxanes to a central {Ni₁₂} core. X-ray single crystal diffraction demonstrate that [7]rotaxanes are formed, with a range of conformations in the crystal. Small angle X-ray scattering supported by molecular dynamic simulations demonstrates that the large molecules are stable in solution and also show that the conformers present in solution are not those found in the crystal. Pulsed EPR spectroscopy show that phase memory times for the {Cr₇Ni} rings, which have been proposed as qubits, are reduced but not dramatically by the presence of the {Ni₁₂} cage.