Dear Colleagues,

Crystal structure determination using X-rays is a well-established mature discipline with important applications in chemistry, physics, biology, environmental science, materials science, medicine, and engineering. It brings together scientists from a wide range of research areas, and is generally regarded as the most definitive and exhaustive form of experimental structural characterisation, yielding information on detailed molecular geometry and on the arrangement of molecules relative to each other in the solid state, as well as the structures of non-molecular extended network structures such as metal–organic frameworks. Recent years have seen major enhancements in aspects of hardware and software, greatly extending the scope and power of the technique, using both single-crystal and powder diffraction data. Possibly the greatest changes have been seen in X-ray detector technology, with the widespread introduction since the 1990s of successive types of area detectors, giving advantages in speed, sensitivity and accuracy.

X-ray source developments in the local laboratory have also been important, with improvements in intensity, stability, and the use of advanced X-ray optics. However, much greater enhancements are achieved by carrying out data collection at a storage-ring synchrotron source. This brings advantages, not only in X-ray intensity (up to several orders of magnitude over even the very brightest of laboratory sources), but also in beam focusing and collimation, in wavelength selection for various purposes, and in the exploitation of the pulsed time-structure of the incident X-ray beam. Most of these advantages have been recognised and used for decades by biological macromolecular crystallography researchers, but have become generally available in chemical and material science areas only in the last 25 years. Today, numerous synchrotron beamlines offer single-crystal diffraction capabilities for so-called ‘small molecule’ applications, though only very few are dedicated to such applications rather than being shared with other diffraction and/or spectroscopic techniques. Rather more beamlines worldwide are available for powder diffraction. Nevertheless, there is a growing output of synchrotron-derived crystal structures, not only of relatively stable materials but also of transient and excited states through the emerging technique of photocrystallography. Both the facilities themselves and the uses to which they are put are undergoing significant development.

This Special Issue, following a similarly themed issue in 2017, provides a forum for reports on technical developments and their applications, and for novel research in areas of crystallography that depend on, or benefit from, the use of present-day synchrotron facilities. For more details please access the following link: https://www.mdpi.com/journal/crystals/special_issues/crystal_structure_studies.

Scientists working in a wide range of disciplines are invited to contribute to this collection. The topics presented in the keywords broadly cover the focus of this Special Issue, but do not restrict it, as synchrotron applications in crystallography are growing and may well include particular approaches that have not yet been described. Innovative contributions are particularly welcomed.

Prof. William Clegg
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• development and use of synchrotron facilities in crystallography
• synchrotron crystallography beamlines
• data collection and processing
• crystal structures from synchrotron data
• synchrotron X-ray diffraction
• synchrotron single-crystal diffraction
• synchrotron powder diffraction
• variable-wavelength studies
• photocrystallography and other time-resolved studies
• extreme conditions crystallography