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 … Read the rest

Jul 172008
 
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 (M. I. M. Tahir, N. H. Rees, S. J. Heyes, A. R. Cowley & K. Prout)

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 … Read the rest

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 … Read the rest

Apr 082008
 

J. Appl. Cryst. (2008), 41, 531-536.    [ doi:10.1107/S0021889808005463 ]

Librational motion within a crystal structure distorts the measured bond distances and angles from their physical values. TLS analysis of a rigid molecule or a rigid part of a molecule allows the calculation of bond-length and angle corrections. Until now, no estimate of the error … Read the rest

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 Read the rest

Sep 152007
 

I worked with Keith for 40 years. When I came to Oxford in 1967 as a fresh post doc, Keith was already the Lecturer in Chemical Crystallography, running a successful research group alongside those of Tiny Powell and Dorothy Hodgkin. Although he was not my supervisor, I quickly learned that it was he who held … Read the rest

 Posted by on September 15, 2007  News
Apr 092007
 

Acta. Cryst. (2007), 63, 303-308. [ doi:10.1107/S0108768106055212 ]

A new polymorph of 2,4-dihydroxybenzoic acid is reported. The structure was characterized by multiple-temperature X-ray diffraction and solid-state DFT computations. The material shows a geometric pattern of hydrogen bonding consistent with cooperativity between the intermolecular carboxylic acid dimer and intramolecular hydrogen bonds. The presence of proton … Read the rest

Dec 172006
 

J. Appl. Cryst. (2006), 39, 842-849.    [ doi:10.1107/S0021889806038489 ]

A sizeable proportion of structures with Z‘ = 2 are thought to exhibit pseudosymmetry, but establishing the extent of the deviation from true symmetry is problematic. By considering both the conformational similarity between the independent molecules and the way in which they are related … Read the rest

Oct 222004
 
Didcot Girls School Science Club

Figure 1: Andrew Cowley demonstrates the Nonius Kccd diffractometer to the Science Club. There is a second diffractometer behind the group

In October, Lynn Nickerson (Science Club Coordinator at Didcot Girls School) arranged for a small group to visit Chemical Crystallography in Oxford University’s new Chemistry Research Laboratory (Figure 1). The group was invited to … Read the rest

Oct 132004
 
Retrieval of Crystallographically-Derived Molecular Geometry Information (I. J. Bruno, J. C. Cole, M. Kessler, Jie Luo, W. D. S. Motherwell, L. H. Purkis, B. R. Smith, R. Taylor, R. I. Cooper, S. E. Harris & A. G. Orpen)

J. Chem. Inf. Comput. Sci. (2004), 44, 2133-2144. [ doi:10.1021/ci049780b ]

The crystallographically determined bond length, valence angle, and torsion angle information in the Cambridge Structural Database (CSD) has been made accessible by development of a new program (Mogul) for automated retrieval of molecular geometry data from the CSD. The program uses a system … Read the rest