Investigations in molecular structure: from scattering to molecular complexes of brominated compounds.
PhD thesis, University of Glasgow.
Full text available as:
The main focuses of this research were to examine the capabilities of solution
techniques to attempt to monitor the nucleation process in crystallisation, and to
investigate structural outcomes of crystallisation processes, with reference to
polymorphism and intermolecular interactions.
To achieve this, work on the investigation of nucleation and early-stage crystallisation
was carried out at the Department of Pharmaceutical Sciences at the University of
Strathclyde and also at the central synchrotron facility of Station 2.1 at the SRS
Daresbury. Small angle X-ray scattering (SAXS) was carried out on solutions of
methyl-4-hydroxybenzoate (pMHB) and 2-bromobenzoic acid. These studies were
carried out after developing solution methods to enable us to determine the point at
which crystals emerged from solution. This was achieved using Focussed Beam
Reflectance Measurements. Structural studies were also carried out on pMHB to
examine its polymorphic behaviour and crystal structures were solved at various
temperatures from 100K to 300K. The crystal structure of methyl-2,5-
dibromobenzoate was also solved at 100K after discovering it sublimes at room
temperature. This structure could only be solved from a twinned crystal and indicated
the appearance of interesting halogen interactions occurring.
Structural studies have also been carried out using the bromanilic acid molecule as a
focus to generate a number of co-crystal complexes to examine their halogen bonding
capability and to determine any structural significances in their formation.
Co-crystal complexes of bromanilic acid and a variety of molecules were made in 1:1
and 1:2 ratios to see if any additional halogen interactions could be observed or
induced, in addition to the expected hydrogen-binding interactions. The co-crystals
included a range of picolines and lutidines as well as bromo-substituted pyridines to
attempt to induce halogen interactions. This generated a number of new compounds
whose structures were determined using single crystal X-ray diffraction and the
interactions were monitored to observed whether any defined patterns with regards to
the tendency of bromanilic acid co-crystallisations to produce predictable patterns of
intermolecular interactions could be determined.
Actions (login required)