Among the various analysis techniques, single crystal X-ray structure analysis can be regarded as the most effective analysis technique for acquiring knowledge about the 3-dimensional configuration of molecules. However, in single crystal X-ray structure analysis, there is also a major problem in that measurement cannot be done if the target sample will not form a single crystal. In addition, even if a crystal is obtained, it is often a twin.
Previously, if the crystal was a twin, the usual approach was to examine the crystallization conditions again, and repeat the process a number of times until a single crystal was obtained. However, due to the development of equipment and software in recent years, it has become possible to carry out a certain amount of analysis even if the crystal is twinning. Therefore, this paper discusses the steps for this procedure, from the method of determining twinning to the method of refinement.