Docking in Molecular Adsorbing Host-Guest Crystals

Molecular Adsorbing Host-Guest (MAHG) crystals composed of cucurbit[8]uril (CB[8]) macrocycles and tetraacid deriva-tives of diphenyl-viologen show diffusion of dihydroxybenzenes in the seemingly non-porous crystalline matrix resulting in highly colored single crystals. As in liquid phase, X-ray crystallography allowed us to show that electron-rich small molecules locate (after diffusion) in the macrocyclic hosts of the non-porous yet permeable crystals, facing the electron-poor viologen fragments to form colored charge transfer (CT) complexes. This phenomenon was confirmed by DFT, modelling the heteroternary complex. This combination of site-directed diffusion in the solid state and charge transfer formation results in rapid (minute timescale) detection of dihydroxybenzenes in aqueous solution by a crystalline material.