Sweet X-ray spectroscopy

We recently realised that Near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy at the C K-edge can distinguish between different saccharides because minute variations in average C-O bond lengths manifest as detectable shifts of the shape resonances associated with these bonds. This opens up the possibility for novel analytical approaches, for example to identify different types of sugars in drug formulations or foods:

NEXAFS Sensitivity to Bond Lengths in Complex Molecular Materials: A Study of Crystalline Saccharides
A. Gainar, J. S. Stevens, C. Jaye, D. A. Fischer & S. L. M. Schroeder
Journal of Physical Chemistry B 119 (2015), in press.

Matt Thomason passed PhD viva

On Friday, 22 March 2013 our group member Matt Thomason passed his PhD examination subject to minor corrections in his PhD thesis, Soft X-ray Spectroscopy of Molecular Species in Solution: Studies of Imidazole and Imidazole/Water Systems.

Congratulations Matt!

PhD Studentship Available

“The crystallisation of polymorphic forms – understanding the mechanism”

Follow this link for more information

Application deadline: 1 June 2012

Summary

Crystallisation from solution is a major process by which chemical companies transform synthetic products into solid forms suitable for formulation into commercial products. It is well known in the literature that impurities can have wide ranging effects on crystallisation, from delaying the onset of nucleation to modifying the particle morphology and changing the crystalline form. Impurities can be introduced from many areas e.g. variation in manufacturing process, solvent stabilisers. During API development, it is common to change the route of synthesis to become more efficient, this can change the levels or change the nature of the impurities present, which can in turn control which polymorph is observed. This may be different to that previously thought to be the thermodynamically preferred polymorph and hence give rise to significant problems of product consistency and reproducibility.

Within pharma companies impurities have been implicated in several polymorphic control problems on active compounds. These are typically rectified by controlling the purity profile, either by column chromatography or other slurry based rework procedure. What has yet to be understood, however, is the mechanism by which the different polymorphs are stabilised by impurities; in particular, the deconvolution of effects of impurities on nucleation of a particular polymorph from the effects on crystal growth. Once understood, this mechanism may be better controlled by modifying parameters in the crystallisation process such as seed point and supersaturation control, reducing the need for time consuming extra reworks or chromatography.

The student will learn and apply modern techniques of solid state and solution chemistry to this problem – X-ray diffraction, FTIR, Raman and UV/vis spectroscopy, calorimetry and high throughput experimentation. The work is supported by a leading UK pharma company.

Funding Notes

Applicants should have or expect to achieve at least a 2.1 Honours MChem/MEng in Chemistry or Chemical Engineering.

Funding for this project covers tuition fees in full at the home rate and annual stipend in excess of the EPSRC minimum (currently £13,590) for the duration of the 3.5 year project, starting 1st October 2012.

Dr Hamizah Mohd Zaki

Our group member Hamizah Mohd Zaki was awarded her PhD on 10 October 2011. Congratulations Hamizah!

Paper accepted for Angewandte Chemie

A study demonstrating that XPS distinguishes reliably between proton transfer and H-bonding in organic systems has now been accepted for publication in Angewandte Chemie.

Crystallography Aided by Atomic Core Level Binding Energies: Proton Transfer vs. Hydrogen Bonding in Organic Crystal Structures
J.S. Stevens, S.J. Byard, C.S. Seaton, G. Sadiq, R.J. Davey, S.L.M. Schroeder
Angewandte Chemie – International Edition 50 (2011), 9916–9918.
DOI:10.1002/anie.201103981

Congratulations Vicky!

Our group member Vicky Fawcett successfully defended her PhD today and passed subject to minor corrections. The title of her thesis is Polymorphism from a Solution Perspective: Rationalisation at the Molecular Level. Congratulations Dr Fawcett!

Success! VERSOX Beamline at DIAMOND Funded

It was announced today that the VERSOX soft X-ray spectroscopy beamline project at DIAMOND Light Source Ltd has been funded. Sven was one of the original proposers of this project, and as a member of the VERSOX Working Group he contributed to developing the case for supporting this beamline project. This beamline will provide our research team with a unique instrument for studying local interactions in organic materials, their nucleation – and surface chemistry in general. What makes VERSOX unique is its versatility – extending the use of soft X-ray spectroscopy beyond its traditional confines in ultra-high vacuum surface physics and chemistry. For example, soft X-ray studies of ‘wet’ soft matter, practical catalytic systems, biomaterials, pharmaceuticals, liquids and solutions will become possible for the first time in the UK. Right from the design stage the project will also take account of the needs of applied science and industrial users. As such it matches perfectly onto our research philosophy, which brings together fundamental science with its practical application.

More information is available by following this link.

Soft X-ray Spectroscopy Beamline Project

We are part of the leadership team for the Versatile Soft X-ray Spectroscopy Beamline Project, which would be the first soft X-ray spectroscopy facility in the UK for the characterisation of liquids, soft matter and organic solids under control of environmental conditions. The Expression of Interest to build such a facility has now been submitted to DIAMOND Light Source Ltd.

Paper accepted in J Phys Chem B

Our paper reporting a multi-technique investigation of a new theophylline complex has been accepted in J. Phys. Chem. B:

Identification of Protonation State by XPS, Solid-state NMR, and DFT: Characterization of the Nature of a New Theophylline Complex by Experimental and Computational Methods
J.S. Stevens, S.J. Byard, C.A. Muryn, S.L.M. Schroeder
Journal of Physical Chemistry B 114 (2010), 13961–13969.
DOI: 10.1021/jp106465u

Oral presentations at CGOM9

Our team will contribute three talks at the 9th International Conference on Crystal Growth of Organic Materials, (CGOM9), 4-7 August in Singapore.

Hamizah will speak about “Surfaces Analysis of Molecular Crystals: Studies of Paracetamol by X-ray Photoelectron Spectroscopy (XPS)

Vicky presents “Polymorphism from a Solution Perspective: Rationalisation at the Molecular Level”.

Sven will summarise our soft X-ray spectroscopy work: “Co-Crystals, Coatings, Contamination and Clusters: Core Level Spectroscopies as a Probe for Local Bonding in Molecular Systems