The future

Structure analysis by X-ray diffraction is an essential technique in the study of molecular and nano structures. However, routine methods will probably prove insufficiently powerful in certain fields of supra- and nano structures. The tendency in supra- and nanomolecular chemistry to design systems which (due to various causes like poor crystallinity etc.) can not be analysed in a routine way asks for the application and development of X-ray methods which elucidate structural features of more 'unusual' compounds.

It is well known that medium sized crystal structures (number of atoms > 100) are still hard to solve by single-crystal diffraction techniques. It is expected that, due to the increasing size of the supramolecular systems under study and the poor crystallinity of assemblies held together by non-covalent interactions, there is a need for more powerful techniques and methods for structure determination. In our group there is a significant expertise in method development (see also DIRDIF and CRUNCH).

The use of modern X-ray equipment (access to CCD diffractometers etc.) and new improved structure solution methods will be essential for studying modern chemical compounds. One- and two-dimensional periodicity of compounds can succesfully be studied by powder diffraction. Insight in one- or two-dimensional periodicity provides useful information about preferred orientation and stacking of molecules which, although no three-dimensional structure is available, may yield essential information about intermolecular interactions. However, the periodicity of supramolecular systems (large d-spacings) and its temperature dependency (e.g. in liquid crystals) needs state-of-the-art equipment and methods. We believe that application of modern powder-diffraction techniques is essential for studying supramolecular assemblies and that development in this direction is needed.
Recently, an advanced new X-ray diffraction facility, a D8 Advance with hot humidity stage and Vantec detector, was installed in Nijmegen. This new facility is certainly a step into the field of modern chemical crystallography!