The Cambridge Structural Database

Abstract

The Cambridge Structural Database (CSD) contains a complete record of all published organic and metal-organic small-molecule crystal structures. The database has been in operation for over 50 years and continues to be the primary means of sharing structural chemistry data and knowledge across disciplines. As well as structures that are made public to support scientific articles, it includes many structures published directly as CSD Communications. All structures are processed both computationally and by expert structural chemistry editors prior to entering the database. A key component of this processing is the reliable association of the chemical identity of the structure studied with the experimental data. This important step helps ensure that data is widely discoverable and readily reusable. Content is further enriched through selective inclusion of additional experimental data. Entries are available to anyone through free CSD community web services. Linking services developed and maintained by the CCDC, combined with the use of standard identifiers, facilitate discovery from other resources. Data can also be accessed through CCDC and third party software applications and through an application programming interface.

Keywords: CIF archive; Cambridge Structural Database; crystal structure database; open data.

Figure 1

Growth of the CSD since 1972, the red bar shows structures added annually.

Figure 2

The increase in the average molecular weight of CSD entries since 1965, with (a) average formula weight per Z′ of metal–organic structures, (b) average molecular weight of heaviest component of metal–organic structures, (c) average formula weight per Z′ of organic structures and (d) average molecular weight of the heaviest component of organic structures.

Figure 3

The increase in resolved disorder in CSD entries since 1965.

Figure 4

The validation step of the CSD Deposition process showing the integration with checkCIF (CCDC, 2016b ▸).

Figure 5

Screenshot of the CSD community Access Structures results page. This is the ‘landing page’ for many referring services based, for example on DOI or CCDC number (CCDC, 2016a ▸).

Figure 6

An illustration of the flow from sample to CSD entry. Solid lines are the elements of the process involving the CCDC. A crystalline sample (a) is put on a diffractometer (b) for an experiment that ultimately results in the experimentally determined coordinates of atoms in the crystal that are captured in a CIF file (c). The CIF file is deposited with the CCDC (d) and may be associated with a scientific article (e). On publication of the article, the structure is validated and enriched by CCDC editorial software and staff (f) to create an entry in the CSD (g). Structures are publicly accessible through CSD community services such as Access Structures (h). Standard identifiers such as DOIs and InChIs facilitate links between articles, structures and other resources. Software developed by the CCDC (i) enables the knowledge embedded in the CSD to be applied to a range of scientific problems including aiding in the determination and refinement of future structures through free resources such as CellCheckCSD (j). The flow of data is largely represented using lamotrigine (Sridhar & Ravikumar, 2009 ▸), the 500 000th entry in the CSD, CSD refcode: EFEMUX01; CCDC number: CCDC 749719; DOI: 10.5517/cct54hl. Image (a) is a crystal of p-aminobenzoic acid (Sullivan & Davey, 2015 ▸) courtesy of Rachel Sullivan and Roger Davey, University of Manchester, CSD refcode: AMBNAC10; CCDC 983122; DOI: 10.5517/cc1200mq. Image (b) courtesy of Andrew Bond, University of Cambridge.