The development, status and scientific impact of crystallographic databases

Nearly 300 000 crystal structures have been reported in the scientific literature and all of them are accessible through the crystallographic structural databases. The historical development, information content and current status of these databases are described, with special reference to methods for data acquisition and structure validation. The relationships that exist between authors, journals and databases are discussed in the light of statistics that predict more than 800 000 structural database entries by the year 2010, more than doubling the output of the last 30 years in less than half the time. Use of the structural databases for data mining and knowledge acquisition is summarized. So far, the vast majority of this research activity has centred around the databases that record small-molecule and macromolecular structures. The creation of knowledge-based libraries of structural information from the existing molecular databases suggests a new era of two-level information provision: the raw-data level and the derived knowledge level. The crystallographic knowledge bases are encouraging the development of software systems that access the stored knowledge to solve complex problems in structural science.