Understanding the Solid State
Despite many years and thousands of pounds spent on research, science still cannot reliably predict whether a material will crystallise, what solvents it will crystallise from and what the final structure will look like. There are over quarter of a million structures in the Cambridge Structural Database and much can be learnt from these. Systematic examination of characteristic materials can also give key insight into the process of crystallisation. Understanding how a material behaves in response to external stimulus (e.g. change in temperature) can also help us to understand how molecules talk to each other.
- Chiral Discrimination
Understanding chiral discrimination has important implications for separation of enantiomers as well as asymmetric synthesis and catalysis. Keith Prout worked extensively on deoxycholic acid studying the chiral selectivity in the host-guest complexes it forms. With Nick Rees he also examined the dynamics in these systems.
More recently we have been looking at chiral selection in the formation of borates with John Brown.
- Crystallisation & Polymorphism
The necessity for good quality crystals mean that crystallisation and structure solution/refinement are closely tied together. Crystallisation is well understood for proteins, however the wide variety exhibited by small molecules and the wide range of solvents available (c.f. water for proteins), means that crystallisation is still, very definitely, a black art.
Concommittent polymorphism
Over the last few years we have tried to crystallise all sorts of materials everything from dyes extracted from spider silk to catalytic metal complexes. Many of the Part II projects have a crystallisation / structure Read more …
- Phase Transitions in Higher Dimensions
It has been suggested that some phase transitions and certain polymorphic systems can best be understood in higher dimensions. Verifying these proposals could revolutionize our understanding of phase transitions and polymorphism – areas critical to the pharmaceutical industry. If we can understand what happens during a phase transition and link polymorphs together in higher dimensions we will gain a better understanding for solid-state reactions.
Gaining this information raises the question of whether it is possible to build solid state molecular structures that are modulated by design. Can we choose Read more …
- Z’ > 1
Z’ > 1: Just a Nuisance, or Something More Interesting?
For many discrete-molecule materials, the molecules pack together to form crystals in a relatively simple way determined by the Space Group. Such materials are said to have Z’=1 (Z-prime). Increasingly, crystallographers are beginning to find crystals in which the basic building block is not just one molecule, but several molecules taken together. Such materials are said to have Z’>1.
These materials Read more …