materials to ensure the stability of any solid form taken forwards to production. The
potential financial impact of the appearance of an unknown and uncharacterised
polymorph with different physicochemical properties is substantial, never mind the
impact on public trust. Hence there has been a move towards using high pressure to
survey different areas of thermodynamic space providing a more robust screen of
potential drug products. So whilst high pressure may have been considered a niche
area of research that is the reserve of earth scientists and physicists, it is certainly not
the case now and it is thanks to the developments made by pioneering groups in the
area of high-pressure crystallography many of whom will be referenced in this
chapter. High-pressure crystallography is a powerful technique that can provide an
alternative pathway to explore molecular materials and should be a consideration of
any solid-state scientist moving forwards through the twenty-first century.
As a preface to the chapter, the work highlighted herein reflects work conducted
by our respective groups placed in the wider context. We have divided the chapter
into different sections so that readers can focus on particular areas of interest.
Section 2 details the different methodologies that have been employed to investigate
materials and the impact these have made on the systems under study. We have tried
to draw on the studies of many groups working in high pressure, and where possible
we have linked the examples in Sections 3 and 4 to the methodologies used where
appropriate and where the method may have impacted on the observed results. This
is not a complete review of the effects of high pressure on molecular materials, but
we hope that it provides an overview of the types of work that have been conducted.
There are a number of reviews of molecular materials at high pressure that we would
encourage the reader to engage with on subjects such as amino acids [2, 8], energetic
materials [5, 9], metal-organic frameworks, chemical reactions as well as the basics
of the technique in general [10, 11].
2 High-Pressure Methodologies
2.1 Standard Methods
In this section we will discuss various methods that can be employed to investigate
organic and metal-organic compounds under high-pressure conditions. The choice
of method will vary depending on the science to be investigated as, in the experience
of the authors, some methods can facilitate phase transitions more readily than
others. The practicalities of loading diamond anvil cells (DACs) using liquids or
single crystals will not be discussed here as they have been covered very well in
other texts; however, we will indicate considerations that may need to be taken into
account in certain circumstances. The authors would recommend the chapter ‘High
Pressure Single-Crystal Techniques’ by Miletich et al. to provide a comprehensive
review of the method [11].
Crystallography Under High Pressures
143
potential financial impact of the appearance of an unknown and uncharacterised
polymorph with different physicochemical properties is substantial, never mind the
impact on public trust. Hence there has been a move towards using high pressure to
survey different areas of thermodynamic space providing a more robust screen of
potential drug products. So whilst high pressure may have been considered a niche
area of research that is the reserve of earth scientists and physicists, it is certainly not
the case now and it is thanks to the developments made by pioneering groups in the
area of high-pressure crystallography many of whom will be referenced in this
chapter. High-pressure crystallography is a powerful technique that can provide an
alternative pathway to explore molecular materials and should be a consideration of
any solid-state scientist moving forwards through the twenty-first century.
As a preface to the chapter, the work highlighted herein reflects work conducted
by our respective groups placed in the wider context. We have divided the chapter
into different sections so that readers can focus on particular areas of interest.
Section 2 details the different methodologies that have been employed to investigate
materials and the impact these have made on the systems under study. We have tried
to draw on the studies of many groups working in high pressure, and where possible
we have linked the examples in Sections 3 and 4 to the methodologies used where
appropriate and where the method may have impacted on the observed results. This
is not a complete review of the effects of high pressure on molecular materials, but
we hope that it provides an overview of the types of work that have been conducted.
There are a number of reviews of molecular materials at high pressure that we would
encourage the reader to engage with on subjects such as amino acids [2, 8], energetic
materials [5, 9], metal-organic frameworks, chemical reactions as well as the basics
of the technique in general [10, 11].
2 High-Pressure Methodologies
2.1 Standard Methods
In this section we will discuss various methods that can be employed to investigate
organic and metal-organic compounds under high-pressure conditions. The choice
of method will vary depending on the science to be investigated as, in the experience
of the authors, some methods can facilitate phase transitions more readily than
others. The practicalities of loading diamond anvil cells (DACs) using liquids or
single crystals will not be discussed here as they have been covered very well in
other texts; however, we will indicate considerations that may need to be taken into
account in certain circumstances. The authors would recommend the chapter ‘High
Pressure Single-Crystal Techniques’ by Miletich et al. to provide a comprehensive
review of the method [11].
Crystallography Under High Pressures
143