Formation and polymorphic phase transitions of crystalline inclusion compounds between 2,2′-bis(9-hydroxy-9-fluorenyl)biphenyl host and acetone guest

The 2,2'-bis(9-hydroxy-9-fluorenyl)biphenyl host compound (1) was found to form various crystalline inclusion compounds with acetone depending on the crystallization conditions or on the method of preparation (inclusion of acetone vapour, co-crystallization from solution). In order to understand and control the formation of these pseudopolymorphic phases regarding potential uses, single crystals of the existing phases (two 1:2 and one 1: 1 compound) were prepared, their structures were solved by single-crystal x-ray diffraction (XRD) analysis and the desolvation and phase transformations were studied using simultaneous thermogravimetry-differential scanning calorimetry (TG-DSC) and variable-temperature powder XRD. The results explain the inclusion and desolvation behaviour and also clarify the observed, apparently accidental formation of a 1:1 or 1:2 inclusion compound at ambient temperature. Copyright (C) 2001 John Wiley & Sons, Ltd.