The design of pharmaceutical cocrystals has initiated widespread debate on the classification of cocrystals. Current attempts to classify multicomponent crystals suffer from ambiguity, which has led to inconsistent definitions for cocrystals and for multicomponent crystals in general. Inspired by the work of Aitipamula et al. (Cryst. Growth Des. 2012, 12, 2147–2152), we present a feasible classification system for all multicomponent crystals. The present classification enables us to analyze and classify multicomponent crystal structures present in the Cambridge Structural Database (CSD). This reveals that all seven classes proposed are relevant in terms of frequency of occurrence. Lists of CSD refcodes for all classes are provided. We identified over 5000 cocrystals in the CSD, as well as over 12 000 crystals with more than two components. This illustrates that the possibilities for alternative drug formulations can be increased significantly by considering more than two components in drug design.
Solvates, Salts, and Cocrystals: A Proposal for a Feasible Classification System
ACS Editors’ Choice – This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.
A classification system for multicomponent crystals is applied to the organic crystals in the Cambridge Structural Database (CSD) in an attempt to reveal the population of structures within each subclass. Seven subclasses of multicomponent crystals are presented, each illustrated by an example of an isonicotinamide crystal structure that can be found in the CSD.
//////////Solvates, Salts, Cocrystals, Proposal, Feasible Classification System