Research Article: Inter­molecular inter­actions and disorder in six isostructural cele­coxib solvates

Date Published: July 01, 2020

Publisher: International Union of Crystallography

Author(s): Andrew D. Bond, Changquan C. Sun.


Six isostructural crystalline solvates of cele­coxib are reported and the inter­molecular inter­actions involving the solvent mol­ecules are described.

Partial Text

Understanding the structures and properties of crystalline solids can be of significant importance for active pharmaceutical ingredients (APIs) (Sun, 2009 ▸). Solid-form screening is an integral part of most pre-formulation activities (Morissette et al., 2004 ▸), with an aim to establish the range of solid forms that can exist for a given API. These generally include both polymorphs and multicom­ponent forms, which may variously be described as salts, cocrystals, solvates, etc. (Aitipamula et al., 2012 ▸).

This set of six isostructural cele­coxib solvates includes small solvent mol­ecules that can accept hydrogen bonds. The host cele­coxib framework is consistent within the set, but it shows quite substantial flexibility in its unit-cell parameters and solvent-accessible void space, and can therefore accommodate solvent mol­ecules of varying size and shape. The crystallographic disorder in several of the structures is understandable on the basis of the local twofold symmetry of the solvent binding site, com­pared to the point symmetry of the solvent mol­ecules. In the absence of any additional hydrogen-bond donors in the solvent mol­ecules, the next most stabilizing inter­actions between the solvent mol­ecules and the cele­coxib framework are C—H⋯O contacts to the S=O groups. The consideration of PIXEL inter­action energies, in combination with geometrical analysis of the crystal structures, is helpful in drawing these conclusions.




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