Understanding High-Pressure Induced Solid State Polymorphism

This research investigates the effect of high-pressure on the solid-state with a particular focus on the crystallisation of liquids using high-pressure. Chapter 1 gives an introduction into the theory underpinning the cryo- and high-pressure crystallisation processes as well as details of X-ray high-pressure diffraction experiments. Chapter 2 outlines the theory behind intermolecular interactions and polymorphism. Chapter 3 details the analysis of two series of simple fluoroaromatics that have been crystallised at both high-pressure and low-temperature, exploring how these forms differ. Chapter 4 examines how the varying the rate of compression in the high-pressure crystallisation of 2-fluorophenylacetylene results in the formation of different polymorphs. Attempts to use high-pressure crystallisation to form different low-melting molecular complexes to those generated through cryo-crystallisation are outlined in chapter 5. Chapter 6 explores the cryo- and high-pressure crystallisation products of isopropyl alcohol, diethyl ether, anisole, dimethylacetylene and acetic anhydride through examination of the intermolecular interactions and crystal packing. The very different molecular geometry of acetic anhydride in the low-temperature and high-pressure forms is discussed. Chapter 7 outlines how the use of different pressure-transmitting media resulting in a metal organic framework behaving differently under the application of pressure.