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The high-pressure and low-temperature structural behaviour of 2,2,2-trifluoroethanol

DOI: 10.1039/C9CE00485H DOI Help

Authors: S. A. Barnett (Diamond Light Source) , D. R. Allan (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Crystengcomm , VOL 6

State: Published (Approved)
Published: June 2019

Open Access Open Access

Abstract: On cooling to 229 K at ambient pressure, 2,2,2-trifluoroethanol freezes to form a crystal structure characterised by hydrogen-bonded molecular chains in the orthorhombic space group Pca21 (form 1). On compression to 0.22 GPa at room temperature, however, liquid 2,2,2-trifluoroethanol crystallises in a structure adopting triclinic P symmetry (form 2). Although the form 1 and form 2 polymorphs are both characterised by the formation of hydrogen-bonded chains, the arrangement of the molecules within the chains are significantly different with the high-pressure form appearing to adopt a more strained configuration. The orientation of the molecules in form 2 is such that the hydrogen bonds in neighbouring chains are in close proximity with a bridging interchain O⋯O contact distance that is of the same order as the O⋯O distances found for the hydrogen bonds. The resulting close pairing of neighbouring catemeric chains produces molecular pillars in the structure of form 2.

Subject Areas: Chemistry

Instruments: I19-Small Molecule Single Crystal Diffraction