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  • The rich structural phase b...
    Barnett, S. A; Bull, C. L; Funnell, N. P; Allan, D. R

    CrystEngComm, 11/2023, Letnik: 25, Številka: 45
    Journal Article

    In the fairly modest temperature and pressure regime of 0-2 GPa and 200-295 K, 2,2,2-trifluoroethanol (TFE) exhibits a remarkable degree of polymorphism, with the observation of four ordered phases (forms 1-4) and a cubic plastic phase (form 5). The ordered phases are characterised by hydrogen-bonded chains, with the crystal structures of the three high-pressure forms (forms 2, 3 and 4) based on the same hydrogen-bonded catemeric motif. The structures and relationships between these phases were determined using a combination of high-pressure single-crystal X-ray diffraction, at ambient temperature, and a series of high-pressure neutron powder-diffraction experiments to ∼6 GPa at 295 K, 245 K and 200 K. As well as allowing the determination of the relative compressibilities of the phases, the neutron powder-diffraction studies also provided a preliminary mapping of the surprisingly rich phase diagram of TFE. A remarkable degree of polymorphism is exhibited in the high-pressure and low-temperature crystal structures of 2,2,2-trifluoroethanol, with the observation of four ordered phases (forms 1-4) and a cubic rotor phase (form 5).