Service restrictions

The IUCr web site and some other IUCr web services (including the submission of new journal articles) will be offline for maintenance for a period of between 2 and 5 hours during the time 09:00 - 17:00 GMT on Saturday 22 September 2018. The IUCr journals site will operate with some restricted functionality during this period.

Welcome to the

International Union of Crystallography

The IUCr is an International Scientific Union. Its objectives are to promote international cooperation in crystallography and to contribute to all aspects of crystallography, to promote international publication of crystallographic research, to facilitate standardization of methods, units, nomenclatures and symbols, and to form a focus for the relations of crystallography to other sciences.

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The importance of careful refinement


A large number of structural determinations of compounds containing 2-hydroxy-3,5-dinitrobenzoic acid and its various deprotonated forms, 2-hydroxy-3,5-dinitrobenzoate or 2-carboxy-4,6-dinitrophenolate, are biased. The reason for this follows from incorrectly applied constraints or restraints on the bridging hydrogen, which is involved in an intramolecular hydrogen bond between neighbouring carboxylic/carboxylate and oxo/hydroxy groups. This hydrogen bond belongs to the category of resonance-assisted hydrogen bonds. The position of the bridging hydrogen seems to be dependent on the pKa(base), though with some exceptions. A stronger basicity enhances the probability of the presence of a phenolate. The problem of the location and refinement of such a bridging hydrogen, as well as that of the hydrogen atoms involved in the hydroxy group, and primary and secondary amine groups, is discussed in a recent article by Fábry [Acta Cryst. (2018). E74, 1344-1357]. It appears that the best model, in many cases, is obtained by fixing the hydrogen-atom positions found in a difference electron-density map while refining its isotropic displacement parameter.

"It is almost futile to state that modern automated diffractometers have enabled single-crystal X-ray structure analysis to become widely applied even by non-experts," commented Dr Fábry. "At the same time, however, it is important to emphasize that a large number of structure determinations of even simple molecules suffer from defects that are caused by inappropriately applied constraints or restraints. These defects bias not only the structure determinations themselves but also - more importantly - the overall information contained in the crystallographic databases. The present study of a whole family of the title molecules demonstrates the importance of careful refinement as well as of inspection of difference electron-density maps. I hope that this experience will reach especially those scientists for whom crystallography is not their specialization but nevertheless use it in their studies."

Posted 14 Sep 2018


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Structural bioinformatics is shaping its community

[3D-BioInfo logo]A new initiative to form an ELIXIR community of structural bioinformaticians in Europe, named 3D-BioInfo, has been proposed. A launch meeting is being held on 19 October 2018 in Basel, Switzerland, and anyone interested in participating is invited to attend.

Structural bioinformatics has a broad impact across the life sciences and provides tools to archive, visualise, analyse, annotate and predict molecular structures. The science of structural bioinformatics is traditionally very strong in Europe offering many software tools, methodologies and databases, as well as community-wide prediction challenges. Its applications cover research activities from structural biology to drug discovery and personalised medicine. It is envisaged that establishing an ELIXIR Community will facilitate deeper integration of the broad range of tools and services already available.

See here for more information.

Posted 07 Sep 2018 

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Simulating cold aqueous environments on Earth and other planetary bodies

[gj5209]Liquid oceans and ice caps, along with ice crusts, have long been considered defining features of the Earth, but space missions and observations have shown that they are in fact common features among many of the solar system's outer planets and their satellites. Interactions with rock-forming materials have produced saline oceans not dissimilar in many respects to those on Earth, where mineral precipitation within frozen seawater plays a significant role in both determining global properties and regulating the environment in which a complex ecosystem of extremophiles exists. As water is considered an essential ingredient for life, the presence of oceans and ice on other solar system bodies is of great astrobiological interest. However, the details surrounding mineral precipitation in freezing environments are still poorly constrained, owing to the difficulties of sampling and ex situ preservation for laboratory analysis, meaning that predictive models have limited empirical underpinnings.

To address this, the design and performance characterization of a transmission-geometry sample cell for use in long-duration synchrotron X-ray powder diffraction studies of in situ mineral precipitation from aqueous ice–brine systems are presented in a recent article in Journal of Applied Crystallography [Thompson et al. (2018). J. Appl. Cryst. 51, 1197-1210]. The cell is capable of very slow cooling rates (e.g. 0.3 °C per day or less), and its performance is demonstrated with the results from a year-long study of the precipitation of the hydrated magnesium sulfate phase meridianiite (MgSO4·11H2O) from the MgSO4–H2O system. Evidence from the Mars Rover mission suggests that this hydrated phase is widespread on the present-day surface of Mars. However, as well as the predicted hexagonal ice and meridianiite phases, an additional hydrated sulfate phase and a disordered phase are observed.

Cold-cell experiments will produce the first in situ observations of mineral formation in freezing aquatic environments that are characteristic of oceans on Earth and other planetary objects. Such novel results will contribute to our understanding of the global processes that occur on, and shape, such bodies.

Posted 14 Aug 2018


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Sine Larsen awarded the Tenth Max Perutz Prize of the ECA

[Sine Larsen]From the website of the European Crystallographic Association:

The Tenth Max Perutz Prize of the European Crystallographic Association (ECA) has been awarded to Professor Sine Larsen from the Department of Chemistry, University of Copenhagen, Denmark.

The Max Perutz Prize is awarded in recognition of Sine Larsen’s multi-faceted contributions to crystallography, including crystal structure analyses of organic molecules and proteins, charge density studies, and the development of synchrotron radiation facilities. Sine Larsen has served crystallographic science and related disciplines in important leadership roles.

Sine Larsen will receive the Prize at the Opening Ceremony of the 31st European Crystallographic Meeting in Oviedo (Spain) on 22 August 2018. On this occasion she will present her Award Lecture.

Professor Larsen served on the IUCr Executive Committee as General Secretary and Treasurer from 1993 to 2005, as President from 2008 to 2011 and as Immediate Past President until 2014.
Posted 07 Aug 2018 


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Andrew Allen appointed as Editor-in-chief of IUCr Journals

[Andrew Allen]We are pleased to announce that Andrew Allen has been appointed as the Editor-in-chief of IUCr Journals. From mid-September 2018, Andrew will be replacing Samar Hasnain, who has completed his six-year term at the helm. We would like to take this opportunity to express our deep appreciation to Samar for his dedicated work and unstinting enthusiasm in developing IUCr Journals, increasing their impact factors, and for launching our flagship journal, IUCrJ.

Andrew is a long-time physicist working in materials science, neutron and X-ray scattering at the US Department of Commerce’s National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA. His editorial connections with the IUCr extend back to 2002 when he first became a Co-editor of the Journal of Applied Crystallography (JAC). He became its Deputy Editor in 2011, and one of JAC’s Main Editors from 2014. During this time, he has acted as Guest Editor for several JAC special issues. Previously, he has also served on the Editorial Advisory Board of the Journal of Physics: Condensed Matter from 1991 to 1996. Andrew’s other main connections with the IUCr have centred on the IUCr Commission on Small-Angle Scattering, of which he has been a member or consultant since 2002, and Chair from 2011 to 2014, the triennial conferences on small-angle scattering (SAS), where he has been active on several organizational or advisory committees, including microsymposia organization and other SAS-related activities, at most triennial IUCr Congresses since 1996 (Seattle). He had already agreed to serve on the International Programme Committee for the IUCr2020 Congress in Prague. Previously, Andrew has served as Vice-Chair and Chair of the ACA’s Special Interest Group on SAS in 2000 and 2001.

Andrew Allen has indicated he feels greatly honoured to be appointed the next Editor-in-chief of IUCr Journals, and in particular to succeed John Helliwell, Gernot Kostorz and Samar Hasnain in this position, all of whom he has had the pleasure to work with during his time as Co-editor, Deputy Editor and Main Editor of JAC. As is well known, scientific journal publishing is facing a rapidly changing business environment, but Andrew looks forward to facing these challenges and opportunities over the coming months and years in his new role as Editor-in-chief.

Posted 18 Jul 2018 


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Mike Glazer appointed as Editor of the IUCr Newsletter

[Mike Glazer]We are very pleased to announce that Mike Glazer has been appointed as the Editor of the IUCr Newsletter, which will be relaunched in an entirely electronic format in summer 2018. Mike will be replacing Bill Duax, who retired last year after 25 years at the helm. We would like to take this opportunity to express our deep appreciation to Bill for his dedicated work and unstinting enthusiasm in disseminating news to the crystallographic community for a quarter of a century.

Mike is Emeritus Professor of Physics at the University of Oxford, UK, and Visiting Professor at the University of Warwick, UK. He has long been associated with the IUCr, most recently as Vice-President from 2014 to 2017 but also as Editor of the Journal of Applied Crystallography from 1990 to 1999 and as a member of many IUCr Commissions. His PhD research between 1965 and 1968 was under the supervision of Kathleen Lonsdale at University College London, UK, working on the crystallography of organic mixed crystals, and his research since then has mainly been in understanding the relationship between physical properties of crystals and their structures. He is perhaps best known for his classification system for tilted octahedra in perovskites.

Mike became interested in crystals at the age of seven, when he found his first natural mineral. This early interest remained with him and eventually took him into the field of crystallography. Since retirement, much of his time is now spent in transferring that enthusiasm to the public in the form of films, exhibitions, podcasts, interviews, lectures and demonstrations. On a recent visit to the IUCr offices in Chester, UK, where the Newsletter will be produced, Mike said that he was delighted to take on the role of Editor of the Newsletter, and looked forward to working with a team of five Regional Editors. "The Newsletter will be an important focus of the IUCr community," he commented, "and the new format will enable us to reach a much larger audience, including decision makers, informing them of the wonders and importance of Crystallography."

The Newsletter will continue to be the place to go for finding out news and developments in crystallography. Two issues are planned for 2018, with four issues per year to appear from 2019 onwards. Feature articles, information about research, meeting announcements and reports, or other items of potential interest to crystallographers may be submitted to the Editor at any time. Items will be selected for publication on the basis of suitability, content, style, timeliness and appeal. Please send contributions to

Posted 05 Jul 2018