Structural analysis at high pressure

Structural analysis at high pressure
Vaclav Eigner
Institute of Physics AS CR, v.v.i., Na Slovance 2, 182 21 Prague 8, Czech Republic

To understand the nature of crystal structure and non-covalent interactions we need to know the crystal structure at various conditions. The easiest condition to control is the temperature, but variations in pressure often lead to more interesting and previously unobserved solid phases. The ambient pressure phases often undergo significant changes with increasing pressure and substances in liquid state at the ambient conditions can be crystallized using the increasing pressure, allowing the researchers to describe otherwise inaccessible crystal structures. During the stay at the University of Edinburgh I focused on the work with pressurization of pyridine methanol mixture, which resulted in new polymorph of pyridine methanol cocrystal and previously unobserved polymorph of pyridine. The samples provided by Dr. Charles Romain from Imperial College London and Prof. Makoto Fujita from University of Tokyo were analyzed both under ambient and high pressures. In the sample from Dr. Romain the shifts in position of loosely coordinated chloride anion were observed, as well as two apparent phase transitions. The samples of crystal sponges provided by Prof. Fujita were measured in the activated and inactivated state. The activated state was then measured under high pressure. The acquired crystal structures will be presented and compared.

Acknowledgement: The work is supported by Operational Programme Research, Development and Education financed by European Structural and Investment Funds and the Czech Ministry of Education, Youth and Sports (Project No. CZ.02.2.69/0.0/0.0/16_027/0008215).