Polymorphism Cambridge Structural Database

Fabian and Kalman [5] retrieved 50 structures from the Cambridge Structural Database, including the polymorphs of 22 compounds, in order to evaluate the frequency of isostructurality among polymorphs. It was found that one-, two-, or three-dimensional isostructurality was exhibited by approximately one-half of the compounds studied. Three-dimensional isostructurality was connected to the gradual ordering of crystal structures, while one- and two-dimensional isostructurality could be related to specific packing interactions. Interestingly, conformational polymorphs were not found to exhibit isostructurality. 

Scheme 3 Relative percentages of organic, organometallic and coordination polymorphic compounds present in the Cambridge Structural Database (CSD, version October 2001) [20a],...

A number of statistical analyses of the literature have been carried out in an attempt to estimate the extent of polymorphism. A search of the Cambridge Structural Database on the keywords polymorph , form , modification and phase indicates that about 3.5% of the -350 000 entries fall into this category. Approximately 25 % of the entries are either solvates or hydrates. At the other end of the spectrum, Byrn has reported that of the >150 compounds submitted for crystal form screening and analysis to SSCI, Inc. 85 % exhibit more than one crystal form, 37% are solvates and 31 % are hydrates [40]. Other studies based on different selection criteria reveal results falling somewhere between these two extremes [41]. For instance, Griesser and Burger have collected information on about 600 polymorphic forms and solvates (including hydrates) pharmaceutical compounds that are solid at 25 °C [41c],... 

Table 3-1. CSD refcodes of organic polymorph clusters up to the recent update of the Cambridge Structural Database (August 2006 update) ...

Sarma JARP, Desiraju GR (1998) Polymorphism and pseudopolymorphism in organic crystals. A Cambridge Structural Database study. In Seddon KR, Zaworotko MJ (eds). Crystal engineering. The design and applications of functional solids. NATO ASI Series, in press... 

Some new insights into the nature of organic crystal polymorphism have been gleaned from a recent systematic analysis [79] of data for polymorphic structures retrieved from the Cambridge Structural Database. A total of 345 crystal structures were reduced to 163 clusters (a cluster referring to a group of two or more polymorphs of the same compound). These clusters comprised 147... 

One approach is to assume that these kinetic factors are in some way represented in experimental crystal structures. Thus, analyses using the information in the Cambridge Structural Database were developed.Although there have yet to be successful independent predictions by this method in the blind tests, this approach holds promise for discriminating among the hypothetical crystal structures within the energy range of potential polymorphism and force field uncertainty. 

The Cambridge Structural Database, p. 141 Crystal Growth Mechanisms, p. 364 Hydrogen Bonding, p. 658 n—n Interactions Theory and Scope, p. 1076 Polymorphism, p. 1129... 

J. van de Streek, Searching the Cambridge Structural Database for the best representative of each unique polymorph, Acta Cryst., B62, 567-579 (2006). 

Fig. 14.16 XRPD patterns of the pure mannitol polymorphs (o, p and 6 modification gained from Cambridge structural database) and exemplaiily one spray dried mannitol sample...

Table 14.1 Problems encountered in the analysis of polymorphic crystal structures in the Cambridge Database. See text for discussion. Cell parameters in A and degrees...

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