Breaking the 10 GPa 'Pressure Barrier' in Organic Solids

A fully-funded PhD studentship is available to work on a collaborative project held at The Centre for Science at Extreme Conditions at The University of Edinburgh on the effect of extreme pressure on molecular materials.

Background

Although use of high pressure to explore polymorphism in molecular solids is increasingly common, only 5% of high-pressure molecular crystal structures have been determined above 10 GPa; beyond 20 GPa, precise data are available only for benzene and threonine. Void space in molecular crystal structures approaches zero above 10 GPa, forcing pressure to be accommodated by covalent bonds and intermolecular interactions. Even though structural data for moderately complex organic compounds beyond this key pressure point are essentially lacking, they are critical for determining the mechanical characteristics of both inter- and intra-molecular bonds. This project will address this important gap in our knowledge by examining the effect of very high pressures on a series of organic materials featuring the key synthons of crystal engineering: hydrogen bonds, dispersion interactions and halogen bonds.

Crystal structures will be determined using state-of-the-art equipment for extreme conditions research, with diffraction data collected in-house and at synchrotron sources. Other techniques include vibrational spectroscopy and periodic density functional theory. The image shows a typical sample in this area of research, crystals grown in situ in a diamond anvil cell ready for study by X-ray diffraction or Raman spectroscopy. The pressure is 1.2 GPa.