Crystallography and Crystal Engineering

This concise treatise is not intended to make readers experts on hardcore crystallography, but to help them to get a qualitative picture of the method and understand the underlying principles and dra vbacks of single crystal X-ray diffraction analysis. To study the theoretical basis of X-ray crystallography in detail, the reader is encouraged to read some excellent X-ray crystallography text books to become fully acquainted vith the theory involved at introductory [10], intermediate [11] or advanced [12] level. 

The other, technically quite different application area, is protein crystallography which deals with very large structures, even virus structures, where VF , can be as high as 100000. However these structures cannot be considered to be crystallographically very accurate, often the resolution is not high enough to determine individual atom positions, and instead amino acid residues are located. Protein R-values are seldom less than 0.15 and the ratio of the number of observed reflections and number of refined parameters is very low ( 5). However protein X-ray structures are considered to be reliable structural information about the conformation and overall structure of the protein in the crystalline state. 

Accurate determination of the structures of molecular inclusion complexes and molecular assemblies has gained in importance in supramolecular chemistry and recently in crystal engineering. Detailed information about the nature of these weak intermolecular interactions is crucial in order to understand and further develop supramolecular systems and understand crystal growth and the properties of crystalline materials. Particularly accurate structural information can be gained in the solid state by single crystal X-ray crystallography. 

---

Lincke, G. (2000). A review of thirty years of research on quinacridones. X-ray crystallography and crystal engineering. Dyes and Pigments, 44, 101-22. [259] Lincke, G. and Finzel, H.-U. (1996). Studies on the structure of alpha-quinacridone. Cryst. Res. Technol, 31,441-52. [263]... 

Lincke, G. (2000). A review of thirty years of research on quinacridones. X-ray crystallography and crystal engineering. Dyes Pigm., Vol.44, Issue 2, pp.101-122. 

Desiraju GR (2014) Chemical crystallography and crystal engineering. lUCrJ 1 380-381... 

The determination of crystal structures by X-ray crystallography provides precise and unambiguous data on intermolecular interactions. Crystal engineering has been defined by Desiraju as the understanding of intermolecular interactions in the context of crystal packing and in the utilization of such knowledge in the design of new solids with desired physical and chemical properties. ... 

It is not within the scope of this chapter to provide tuition in crystallography. For this the reader is referred to many valuable texts [1] or to intensive crystallography schools such as those run by the British Crystallographic Association and the American Crystallographic Association [2]. The aim of the following sections is to provide a brief overview of what diffraction methods can offer in the context of crystal engineering. Diffraction of X-rays and neutrons by single crystals and... 

Diffraction is the key experimental technique in crystal engineering. It provides the means of accurately characterising the product of a crystal synthesis endeavor. However, the applications of diffraction are much wider than simply structure determination. An overview of the contribution of crystallography to many areas of chemistry is provided in a recent issue of the journal Chemical Society Reviews dedicated to crystallography [49]. The purpose of this chapter has been to take a broader view of diffraction studies and their present and future potential to play an important role in the continued development of all aspects of crystal engineering. 

---