Unexpected Behaviour in Derivatives of Barluenga's Reagent

Aug 302018
 

Chemical Communications 2018, 54, 9849 – 9852 [doi:10.1039/C8CC05430D]

For the collidine analogues of Barluenga’s Reagent (IPy2BF4) reported, a flat cation is necessary for the generation of a modulated phase, in keeping with the “Ratchet Model” theory [Kim et al., Crystal Growth & Design, 2014, 14, 6294]. Attempts to study “diffuse modulation” in Br(Coll)2ClO4 have shown that these non-Bragg features disappear very rapidly on exposure to synchrotron radiation, an effect thought to be caused by the radiation damage disrupting the lattice vibrations that cause the modulation.

 

Radiation Damage

ECM31, Oviedo and ECA Crystallographic Computing School, Mieres

Aug 292018
 

The 31st European Crystallography Meeting was held in Oviedo, Spain from 22-26 August 2018.

During the meeting George Sackman presented a poster (MS10-P05) on recent neutron diffraction work with Richard Cooper and Alison Edwards: Disordered or not: A cautionary tale when inferring proton disorder solely from X-ray and computational data.

Richard Cooper gave a presentation (GI-MS47-O5) in the Saturday afternoon session How to… take your next steps in crystallography, based on experience of a career which despite including several areas of science and organisations rarely strayed outside the OX postcode.

On Sunday afternoon Amber Thompson presented (MS27-O5) Adventures in modulation: derivatives of Barluenga’s reagent, including work from Lewis Morgan, Yejin Kim, Emma McKinley, Jack Blandy, Claire Murray and Kirsten Christensen, in the session Quasicrystals: theory and
experiment.

Prior to the meeting, Richard Cooper was a tutor at the ECA Crystallographic Computing School in Mieres, organised by the ECA SIG 9 and gave a lecture on Programming Crystallographic Symmetry.

Crystals v6999

Jul 182018
 

The CRYSTALS v6999 installer for Windows 7/10 is now available.

Please report problems. The version number (6999) refers to a specific snapshot of the source code enabling us to better identify and fix bugs.

Key changes between 14.6720 and 14.6999
Added some trial shortcut keys to the menus. Ctrl-O: open file dialog, Ctrl-R: setup refinement, Alt-R: do refinement, Alt-S: refine scale, Alt-C: sfls/calc, Ctrl-H: hydrogen fourier, Ctrl-Y: cameron, Ctrl-W: wilson, Ctrl-F: fo vs fc, Ctrl-A: agreement analysis, Ctrl-R: rotax!
Added menus to the xeditorgl script so that Ctrl+S, Alt-F4 key combination works for save and exit.
Fix quoting of paths with spaces in SCRIPTS so that CRYSTALS can be installed in, and process data in, paths with spaces.
Removed default low angle cutoff in L28 – should be handled by instrument software.
Allow negative twin element scales. Setting negative scales back to zero was breaking twin element scale constraints.
Tool-help option (see Tools menu) shows quick explanatory text before carrying out immediate tasks from menus.
Punch of L30 implemented – all lists can now be punched!
Dialog and options for launching SHELXT (solve menu).
Fix weird bug that caused crash when importing structures containing cobalt and using Cu X-ray scattering factors.
New shelx2cry by Pascal used for .ins and .res conversion – much better conversion of standard SHELX syntax.
‘Sticky refine’ mode code improved and made user interface more intuitive.
Removed old shift rescaling code, it slowed convergence of some key parameters.
New leverage information output of restraints (#CHECK). Restraints with no leverage are pointless, while a leverage of ~1 indicates they dominate refined value of parameter of function of parameters.
Code to output leverage data (punch=numpy) during SFLS. Data in python format to allow user calculations to be added.

An enhanced set of displacement parameter restraints in CRYSTALS

Jun 242018
 

Journal of Applied Crystallography, 2018, 51, 1059-1068. [ doi: 10.1107/S1600576718007100 ]

The implementation and use of a set of new displacement parameter restraints is described. Anisotropic displacement parameters account for a large proportion of the parameters in a crystallographic refinement, but very few restraints for conveniently controlling their values have been implemented in standard crystallographic refinement programs.

The Zurich School of Crystallography in Tianjin

Jun 172018
 

The Great Wall of China (Huangyaguan section)Though it should be an off-year, the long-running biennial Zurich School of Crystallography visited the Health Science Platform of the University of Tianjin in June 2018 to teach a group of international researchers how to use single crystal X-ray crystallography.

Richard Cooper joined the Swiss delegation of tutors and gave lectures on space group determination and the use of Hirshfeld surfaces in crystal structure analysis.

Right: The Great Wall of China (Huangyaguan section): Lukas Palatinus and Hans-Beat Bürgi in the distance.

 

Prizes at the BCA Spring Meeting

Apr 052018
 

Kiaora Tolmie recieving the CCG Poster PrizeThe 2018 Meeting of the British Crystallographic Association was held at Warwick University where Chem. Cryst. was well represented.  The meeting started with the Young Crystallographers Satellite meeting, during which Lewis Morgan’s oral presentation was so “eggsellent” that he won the Industrial Group Prize for the best talk, and with it, the dubious honour of presenting it again as a plenary in the main meeting.

At the conference dinner Kiaora Tolmie received a CCG CrystEngComm poster prize for her poster on hard-to-crystallize materials, and James Bird was awarded the YCG I’m-a-scientist-get-me-out-of here prize for the poster presenter who most clearly and enthusiastically communicated their results.

Congratulations to all three winners!

 

Lewis Morgan delivering his prize-winning presentation at the BCA Spring Meeting 2018

Lewis Morgan delivering his prize-winning presentation

 

A full list of the presentations from Chem. Cryst.:

George A. Sackman & Richard I. Cooper
Distinguishing Disorder: A Molecular Dynamics Approach (Poster Presentation)

Kiaora L. M. Tolmie & Richard I. Cooper
Structure Determination of Hard-to-Crystallize Materials (Poster Presentation)

Lewis C. F. Morgan, Jack N. Blandy, Claire A. Murray, Kirsten E. Christensen & Amber L. Thompson
Improving Our Understanding of Modulation in Molecular Materials (Poster & Oral Presentation)

James M. Bird & Richard I. Cooper
A Comparison of Molecular Dynamics Techniques for Simulation of Thermal Disorder in Molecular Crystals (Poster Presentation)

Oliver J. A. Bar & Richard I. Cooper
A Study of Phase Transitions in Organic and Metal-organic Inclusion Complexes through Molecular Dynamics Simulation (Poster Presentation)

Richard I. Cooper
CrysPy: CRYSTALS in Python (Poster Presentation)

Amber L. Thompson
When are Bad Data Good Data? (Keynote Oral Presentation)