Congratulations, Dr Chang!

Our group member Sin-Yuen Chang has passed her PhD viva subject to very minor corrections, and has already submitted the revised thesis, titled “Studies of Metal Speciation and Nucleation in Complex Functional Liquid Systems“. Sin-Yuen has already taken up a position at Diamond Light Source, and a visiting appointment at the University of Leeds, through which she will continue to collaborate with our team. Congratulations , Dr Chang!

JACS paper!

Under leadership of Akihiro Uehara a combined electrochemical/X-ray absorption spectroscopy study deconstructing the famous Brust-Schiffrin synthesis of gold nanoparticles has been carried out. The results elucidates some of the transformations taking place during this two-phase synthesis. The results show that the reaction at the oil-water interface includes a time dependent evolution of the Au(I) species formed as intermediates, and identifies the nature of the (also time dependent) thiolate side products.

Electrochemical Insight into the Brust-Schiffrin Synthesis of Au Nanoparticles
A. Uehara, S. G. Booth, S.-Y. Chang, S. L. M. Schroeder, T. Imai, T. Hashimoto, J. F. W. Mosselmans & R. A. W. Dryfe
Journal of the American Chemical Society 137 (2015) 15135–15144.
DOI: 10.1021/jacs.5b07825

2015 Publications So Far…

The group has had a good run of publications this year. So far our 2015 output of papers includes:

Intermolecular Bonding of Hemin in Solution and in Solid State Probed by N K-edge X-ray Spectroscopies
R. Golnak, J. Xiao, K. Atak, J. S. Stevens, A. Gainar, S. L. M. Schroeder & E. F. Aziz
Physical Chemistry – Chemical Physics 17 (2015), accepted.
DOI: 10.1039/C5CP04529K
Fenton-Like Oxidation of 4−Chlorophenol: Homogeneous or Heterogeneous?
C.-C. Kuan, S.-Y. Chang, S. L. M. Schroeder
Industrial & Engineering Chemistry Research 54 (2015) 8122–8129.
DOI: 10.1021/acs.iecr.5b02378
Gold Deposition at a Free-Standing Liquid/Liquid Interface, Evidence for the Formation of Au(I) by Microfocus X-ray Spectroscopy (μXRF and μXAFS) and Cyclic Voltammetry
S. G. Booth, A. Uehara, S.-Y. Chang, J. F. W. Mosselmans, S. L. M. Schroeder, R. A. W. Dryfe
Journal of Physical Chemistry C 119 (2015) 16785–16792.
DOI: 10.1021/acs.jpcc.5b05127
Synthesis of Polyurea-Polyether Core Shell Nanoparticles via Spontaneous Nanoprecipitation
P. Locatelli, S. Woutters, C. Lindsay, S. L. M. Schroeder, J. H. Hobdell & A. Saiani
RSC Advances 5 (2015) 41668-41676.
DOI: 10.1039/c5ra03662c
Structure and Bonding in Au(I) Chloride Species: A Critical Examination of X-ray Absorption Spectroscopy (XAS) Data
S.-Y. Chang, A. Uehara, S. G. Booth, K. Ignatyev, J. F. W. Mosselmans, R. A. W. Dryfe, S. L. M. Schroeder
RSC Advances 5 (2015) 6912-6918.
DOI: 10.1039/C4RA13087A
Proton Transfer, Hydrogen Bonding, and Disorder: Nitrogen NEXAFS and XPS of Bipyridine-Acid Salts and Co-crystals
J. S. Stevens, L. K. Newton, C. Jaye, C. A. Muryn, D. A. Fischer & S. L. M. Schroeder
Crystal Growth & Design 15 (2015) 1776-1783.
DOI: 10.1021/cg5018278
Self-Association of Organic Solutes in Solution: A NEXAFS Study of Aqueous Imidazole
M. J. Thomason, C. R. Seabourne, B. M. Sattelle, G. A. Hembury, J. S. Stevens, A. J. Scott, E. F. Aziz & S. L. M. Schroeder
Faraday Discussions 179 (2015) 269-289..
DOI: 10.1039/C5FD00005J
Chemical Speciation and Bond Lengths of Organic Solutes by Core Level
Spectroscopy: pH- and Solvent-Influence on p-Aminobenzoic Acid

J. S. Stevens, A. Gainar, E. Suljoti, J. Xiao, R. Golnak, E. F. Aziz & S. L. M. Schroeder
Chemistry – A European Journal 21 (2015) 7256-7263.
DOI: 10.1002/chem.201405635

Paper on Novel Spectroelectrochemical Technique

A windowless electrochemical cell for the spectroscopic investigation of the liquid-liquid interface, using a dual droplet configuration, has been designed. The setup permits in situ probing of the bulk solutions and the interfacial region by fibre-optic UV-vis spectroscopy, microfocus X-ray fluorescence (XRF) elemental mapping, and microfocus X-ray absorption near-edge structure (micro-XANES) spectroscopy. The electrodeposition of Au, induced by ion transfer of the tetrachloroaurate complex from a halogenated solvent (containing a weak reducing agent) to the aqueous phase, has been monitored by a combination of the three techniques. The reaction can be followed in-situ by UV-vis spectroscopy by detecting the oxidised form of the reducing agent. Voltammetric evidence suggests the formation of interfacial Au(I) species, whereas micro-XANES detect the presence of metallic Au(0).

In Situ Spectroelectrochemistry at Free-Standing Liquid-Liquid Interfaces: UV-vis Spectroscopy, Microfocus X-ray Absorption Spectroscopy and Fluorescence Imaging
Y. Gründer, J.F.W. Mosselmans, S.L.M. Schroeder & R.A.W. Dryfe
Journal of Physical Chemistry C 117 (2013), 5765–5773.
DOI:10.1021/jp312060f

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.

New publication: gold nanoparticle nucleation at liquid/liquid interfaces

The first publication from the EPSRC/NSF collaboration has appeared in press:

Inhibited and Enhanced Nucleation of Gold Nanoparticles at the Water|1,2-Dichloroethane Interface
Y. Gründer, H.L.T. Ho, J.F.W. Mosselmans, S.L.M. Schroeder, R.A.W. Dryfe
Physical Chemistry Chemical Physics 13 (2011), 15681-15689.
DOI:10.1039/C1CP21536A

New research grant: The Designer Nanoparticle

An NSF/EPSRC proposal with Robert Dryfe and Mark Schlossman to study nanoparticle nucleation and growth at liquid-liquid interfaces with synchrotron radiation techniques (XAS and GIXS) has been successful.

Follow this link for more details