Crystalline alcoholic inclusions of singly-bridged triarylmethanol hosts. Synthesis, X-ray crystal structures and binding modes of five inclusion compounds

Five alcoholic inclusion compounds of singly-bridged triarylmethanol hosts have been synthesized and investigated by X-ray diffraction. In four cases recognition of the alcoholic guest by the host is characterized by a coupled system of hydrogen bonds in the form of closed loops. The centro-symmetric hydrogen-bonded rings, with full hydrogen bond saturation, are created by four –OH groups belonging to two host and two guest molecules. In the fifth complex, however, ‘anomalous’ hydrogen-bonded 2:1 host:guest associates are formed without full saturation of hydrogen bonds. In the crystals the hydrogen-bonded units are held together mostly by ordinary Van der Waals' forces, occasionally supported by electrostatic C–H ⋯ O interactions.