Pillarplexes: A Metal–Organic Class of Supramolecular Hosts

Novel octanuclear NHC complexes of gold­(I) and silver­(I) form metallocavitand structures with very defined tubular cavities and are able to selectively host linear molecules, exemplarily demonstrating 1,8‑diaminooctane as a model guest molecule. The solubility of the host-compounds is easily adjusted by simple anion exchange reactions so that the compounds can be made soluble in water wherein they exhibit a high longtime stability. The gold­(I) complex is emissive in aqueous solutions, which enables a determination of the binding constant to the diamine via luminescence quenching. The host–guest interaction was further investigated by isothermal titration calorimetry, NMR spectroscopy, and X-ray crystallography.