Amber L. Thompson

ECM 25

Aug 212009

The 25th European Crystallographic Meeting was held in the Harbiye Museum and Cultural Centre in the beautiful city of Istanbul. It was a very eventful week, and contributions to the conference made by Chem. Cryst. include:

N. David Brown, James Haestier, Mustapha Sadki, Amber L. Thompson & David J. Watkin
A Further Improved Structure Matching Algorithm (Poster)

James Haestier
Handling of Cell Errors and their Effect on Derived Parameters (Poster)

Mustapha Sadki
New Modelling for Disordered Atoms in Free-form Based Hybrid Refinement and Visual Representation (Poster)

Mustapha Sadki
The Application of Novel Modelling and Refinement Strategies to Crystallography (Presentation)

Amber L. Thompson & David J. Watkin
Absolute Configuration Determination – Is there More Information in the Data? (Poster)

David J. Watkin, Richard I. Cooper & Amber L. Thompson
CRYSTALS: Refinement and Validation Tools (Poster)

David Watkin
The Future of Small Molecule Software (Session Chair)

Dr. Jeppe Christensen

Aug 212009

Jeppe’s specialist areas are crystallographic instrumentation, experiment design, weak diffraction, twinning and modulation. He is also very knowledgeable about software and the theoretical basis of crystallography. Formerly beamline manager at the Swedish synchrotron facility MAX IV Laboratory, where he operated the small molecule and powder diffraction beamline, Jeppe is currently Research Officer in the Dynamical Structural Science group at the Research Complex at Harwell where he is involved in the development of time resolved crystallography.

BCA Spring Meeting 2009

Apr 212009

The 2009 British Crystallographic Association Spring Meeting was held at the University of Loughborough. Contributions from Chem. Cryst. included:

N. David Brown, James Haestier, Mustapha Sadki, David J. Watkin & Amber L. Thompson
A Further Improved Structure Matching Algorithm (Poster)

James Haestier
Effects of Cell Errors on Derived Parameters (YC Presentation)

James Haestier
Computation of Cell Errors Effects on Derived Parameters (Poster)

Mustapha Sadki & David J. Watkin
New Framework for Reliable Refinement Data Types (Presentation)

David Watkin gives the Kathleen Lonsdale Lecture

Apr 012009

David Watkin gives the Lonsdale Lecture

Every two years, the Young Crystallographers Group of the British Crystallographic Association nominate a speaker to give the prestigious Kathleen Lonsdale Lecture. Traditionally, they invite well respected scientist who has a good rapport with students. This year the Lonsdale Lecturer was David Watkin who is well known within the community, principally as a result of his involvement with the highly respected refinement software CRYSTALS, developed in Oxford and through the BCA biannual teaching school which he co-founded twenty-five years ago.

BCA Award for David Watkin

Apr 012009

Presentation to mark David Watkin becoming Honorary Member of the BCA

David Watkin has been elected as Honorary Member of the British Crystallographic Association for his outstanding services to the organisation and crystallography as a whole. The award was made in particular recognition of his role as a teacher, in both the UK and worldwide. The presentation was made at the annual meeting of the BCA which was held at the end of April at Loughborough University.

Dr. Kirsten E. Christensen

Feb 162009

Kirsten has been a visiting scientist in the lab since February 2009. She spends one to two days in Oxford doing synthesis of Open-framework germanates and taking a keen interest in difficult structures. Kirsten’s primary research interest is in “Crystallography on the edge”, studying superstructures, diffuse scattering and modulated structures. As a natural part of being a post doc at Diamond she also takes an enthusiastic interest in collecting data on small and challenging crystals. Kirsten is also local contact when the Oxford BAG goes to Diamond for beamtime on I19.

The Absolute Configuration of 1-Epialexine Hemihydrate

Dec 152008

Acta Cryst. (2008), C64, o649-o652. [ doi:10.1107/S0108270108037086 ]

The absolute and relative configurations of 1-epialexine are established by X-ray crystallographic analysis, giving (1S,2R,3R,7S,7aS)-1,2,7-trihydroxy-3-(hydroxymethyl)pyrrolizidine. The compound crystallizes as the hemihydrate C₈H₁₅NO₄·0.5H₂O, with hydrogen bonds holding the water molecule in a hydrophilic pocket between epialexine bilayers. In addition, a comparison was made between results obtained from examination of the Bijvoet pairs from data sets collected using molybdenum and copper radiation.

Discrimination of Chiral Guests by Chiral Channels: Variable Temperature Studies by SXRD and Solid State C-13 NMR of the Deoxycholic Acid Complexes of Camphorquinone and endo-3-Bromocamphor

Jul 172008

Chirality (2008), 20(7), 863-870. [ doi:10.1002/chir.20561 ]

3 alpha,12 alpha-Dihydroxy-5 beta-cholan-24-oic acid (deoxycholic acid DCA) is able to discriminate between the R- and S-enantiomers of camphorquinone and endo-(+)-3-bromocamphor and select only the S-enantiomers from a racemic mixture. DCA forms novel well ordered 1:l adducts with (1S)-(+)-camphorquinone and (1S)-endo-(-)-3-bromocamphor, both of which have been characterized by single crystal X-ray diffraction (SXRD). When DCA is cocrystallized with (RS)-camphorquinone and (RS)-endo-3-bromocamphor, 1:1 adducts of the S-enantiomers are produced together with crystals of the free racemic guest. In contrast, in the absence of (1S)-(+)-camphorquinone, DCA forms a 2:1 adduct with (1R)-(-)-camphorquinone. In this 2:1 adduct the guest is disordered at ambient temperature and undergoes a phase change in the region 160-130 K similar to that observed for the ferrocene adduct, but with only partial ordering of the guest. The SXRD structure of the low temperature form and the variable temperature C-13 CP/MAS NMR are reported. Cocrystallizing DCA with (1R)-endo-(+)-3-bromocamphor gives the free guest and a glassy solid.

Packing diagram of (deoxycholic acid)2:ferrocene at 100K viewed along the crystallographic a-axis; hydrogen bonds are represented by dotted lines

Structure Refinement: Some Background Theory and Practical Strategies

May 152008

J. Appl. Cryst. (2008), 41, 491-522. [ doi:10.1107/S0021889808007279 ]

Most modern small-molecule refinement programs are based on similar algorithms. Details of these methods are scattered through the literature, sometimes in books that are no longer in print and usually in mathematical detail that makes them unattractive to nonprogrammers. This paper aims to discuss these well established algorithms in nonmathematical language, with the intention of enabling crystallographers to use their favourite programs effectively.

BCA Spring Meeting 2008

Apr 012008

The Annual Meeting of the British Crystallography Association was held in York. Contributions from Chem. Cryst. included:

Anna Collins, Richard I. Cooper, Andrew R. Cowley, David J. Watkin
2-(1-Hydroxy-2-methyl-propyl)-2,5-dihydro-furan-2-carboxylic acid diisopropylamide: A study of a phase transition to a pseudosymmetrical Z′=2 structure (Poster)

James Haestier, Mustapha. Sadki, Amber L. Thompson and David J. Watkin
Cell Parameter Standard Uncertainties and their Effect on Crystallographic Data (Poster)

Mustapha Sadki, James Haestier, Amber L. Thompson & David J. Watkin
Computational Infrastructure for Bridging the Gap between Previous and Future Generations of Crystallographers (Poster)

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