Structural studies and classification of brucine co-crystallisations

• Main Author: Dijksma, Fokke J. J.
• Published: University of Edinburgh 1999
• Subjects: 547.78
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.649549

This thesis is concerned with the structural studies of Brucine and some adducts. The use of brucine as a resolving agent is well known, but the use of the brucine a co-crystallising agent for molecules which crystallise with difficult or not all is unknown. Carbohydrates are notorious for their difficult crystallisations if they can be crystallised at all. One aim of this thesis, explained in Chapter 1, is to investigate this use of brucine by crystallographic means. The experimental methods by which this was achieved are described in Chapter 2. Chapter 3 describes the simplest of the structures; the brucine hydrates. This comprises three brucine structures; the anhydrous, di-hydrate and tetra-hydrate. The description of these structures by means of crystallography, thermal analysis and powder diffraction gives a solid basis for further discussion. In particular, anhydrous brucine taken as a 'groundstate' is important in this aspect. Chapters 4 and 5 discuss the co-crystallisation of brucine with uronates and nucleic acids. These classes of molecules are treated as precursors of carbohydrates and show the tendency of brucine to form ribbons in crystalls. They crystallise readily with brucine. The conformation of each acid is compared to conformations found in other crystal structures of these acids and found to be related. Chapter 6 describes the dicarboxylic acid series (oxalic acid to glutaric acid) and derivatives pyruvic, lactic and oxamic acid. These acids were chosen to co-crystallise with brucine to investigate the effect of slight changes between them and on structural methods. Brucine is shown again to favour crystallisation in ribbons, although with a few notable exceptions. In Chapter 7 the same dicarboxylic acids are crystallised with strychnine to make a comparison between brucine and strychnine co-crystallisations. Here the predominant strychnine packing is a bilayer, but crystallisations with uronates and nucleic acids are not favourable.