Eight easy steps to preparing manuscripts containing crystal structure deteminations.
As each journal has its own special requirements and instructions pertaining to the reporting of crystal structure determinations (and other results!), it is essential to consult the Instructions to Authors for the journal concerned in order to find out exactly what is required, and to look at recent articles in the journal to get a feel for the layout and content of papers in that jornal. It is recommended that you follow the instructions to the letter. Failure to do so gives the journal an easy excuse for rejection of the paper.
The main variations are usually the amount of material to be reported in the Results and Experimental sections, in the Supplementary Material and whether the crystallographic data has to be submitted to the journal or a database prior to submission of the manuscript.
The X-ray Laboratory personnel can assist with the preparation of experimental details and the material to be deposited with the CCDC or uploaded to the journal, if desired. Please give sufficient advance notice so that the material can be prepared, especially if you have several structures in one paper.
Listings of the observed and calculate structure factors for each crystal structure must only be submitted with the manuscript if the paper is being sent to one of the Acta Crystallogaphica family of journals. If you need structure factor tables, please come to the X-ray Laboratory and ask for them to be generated.
The material to be included in this section of a paper is mainly at the authors' discretion and usually depends on the contribution that a structure determination makes to the main theme of the paper. If the structure determination merely served to confirm the product of a synthesis, the inclusion of a picture of the molecule will probably be adequate. In some cases, such as with several very similar molecules, a simple statement that the product was confirmed by an X-ray structure determination might even be enough.
If you are more interested in particular structural features, such as bond lengths, angles, torsion angles, molecular conformation or topology, crystal packing or hydrogen bonding interactions, these can be discussed in more detail. A table of selected parameters might also be useful if more than a few parameters need mentioning, or if several structures are to be compared. Unusual features in a structure or in the determination thereof should also be mentioned.
It is important to include the standard uncertainties (s.u.) in any quoted parameter and to be careful to take these into consideration when comparing parameters. For example, the true value of a bond length given as 1.425(5) Å could lie anywhere between 1.410 and 1.440 Å. This bond length would not be significantly different from one of 1.453(5) Å, since, within the 3 s.u. (99%) confidence limits, the latter bond could be as short as 1.438 Å, just inside the upper limit of the former bond.
It is essential to provide a diagram that clearly displays the features you wish to illustrate. Ideally, one should include a fully labelled view of the molecule showing the displacement ellipsoids (i.e. an ORTEP plot). Stereoviews are not necessary, but can be used if you prefer.
A diagram showing displacement ellipsoids immediately transmits to the reader an impression of the quality of the structure and of the vibrational motion or potential disorder in the structure. The use of arbitrary spheres for the atoms (ball-and-stick diagram) is less satisfactory because of the consequent loss of this information, so should be avoided in general, but there may be circumstances where the use of arbitrary spheres for atoms improves the clarity of the diagram.
The diagrams produced by the X-ray Crystallography facility are usually in TIFF format and can readily be inserted into your Word documents and resized if desired.
The TIFF files can also be edited easily with the Macintosh program GraphicConverter. Any part of the picture, such as labels, can be moved or deleted, new features (e.g. arrows, lines) can be drawn in and text or labels can be added. Use the Picture/Show Toolbox menu to obtain the editing functions. If you wish to add text, a very large font size is needed, e.g. 120 points. Double-click on the text option in the Toolbox to choose font size and type. The colour definition of each colour already present can also be changed with the Picture/Colors menu.
Download the example Word document, which illustrates one way of presenting the usual crystallographic experimental text and tabular data that should be included in a publication being prepared for a journal requiring full experimental details, even if the structure itself is not discussed in any detail in the paper. The specific details usually vary from structure to structure and can be deduced by reading the individual structure reports. This example also demonstrates how the details for multiple structures can be combined. Some journals require a more abridged format, or even just the crystal data as in-line text. Be sure to check out the usual style adopted by the journal you wish to submit the paper to.
Except for some ACS journals and the journals of the IUCr (Acta Crytallographica family) and Z. Krist., most other journals require that the crystallographic data for the paper be deposited with the Cambridge Crystallographic Data Centre (CCDC) before the manuscript is submitted to the journal. The CCDC will then provide a deposition number for each deposited structure (e.g. nn1, nn2, nn3), which must be included in paper as a footnote, reference or experimental details as follows:
CCDC-nn1-nn3 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
More information about deposition procedures is available from the CCDC website.
If this procedure is followed, it is not necessary to submit any of the crystallographic data as supplementary material, because the referees can obtain the data directly from the CCDC by quoting the deposition number.
When you are preparing a manuscript, the X-ray Laboratory staff will be happy to deposit the required data and obtain the deposition number if you do not wish to do this yourself. Please give sufficient advance notice so that the submission can be prepared, especially if you have several structures in one paper. The CCDC usually provides the deposition numbers within a few hours. For each structure to be deposited, the following information is required:
Preparing a paper for publication in Acta Crystallographica (Section C or Section E) is very easy once the concept of the special submission procedures has been mastered. The manuscript and all associated data are submitted electronically in the format of a Crystallographic Information File (CIF), while the diagrams and structure factors are uploaded as separate files.
Information on the CIF file format, details of the requirements for the preparation of electonic manuscripts and the submission procedure are available from the Author Services Web pages for Acta Crystallographica Section C and Section E.
The X-ray Laboratory has the necessary software to generate almost the entire manuscript automatically. All you need to do is to write a suitable introduction and discussion for the paper in completely unformatted text. If you wish to prepare a paper to submit to Acta Crystallographica, please come to the X-ray Laboratory where we can discuss the necessary procedures and demonstrate how easy it is to prepare manuscripts for this journal.
Acta Crystallographica, Sections A to F are journals of the International Union of Crystallography and are available on-line to subscribers through Crystallography Journals Online.