Intermolecular interactions and disorder in six isostructural celecoxib solvates

Abstract

Six isostructural crystalline solvates of the active pharmaceutical ingredient cele­coxib {4-[5-(4-methyl­phen­yl)-3-(tri­fluoro­meth­yl)pyrazol-1-yl]benzene­sul­fon­amide; C17H14F3N3O2S} are described, containing di­methyl­formamide (DMF, C3H7NO, 1), di­methyl­acetamide (DMA, C4H9NO, 2), N-methylpyrrolidin-2-one (NMP, C5H9NO, 3), tetra­methyl­urea (TMU, C5H12N2O, 4), 1,3-dimethyl-3,4,5,6-tetra­hydro­pyrimidin-2(1H)-one (DMPU, C6H12N2O, 5) or dimethyl sulfoxide (DMSO, C2H6OS, 6). The host cele­coxib structure contains one-dimensional channel voids accommodating the solvent mol­ecules, which accept hydrogen bonds from the NH2 groups of two cele­coxib mol­ecules. The solvent binding sites have local twofold rotation symmetry, which is consistent with the point symmetry of the solvent mol­ecule in 4 and 5, but introduces orientational disorder for the solvent mol­ecules in 1, 2, 3 and 6. Despite the isostructurality of 1-6, the unit-cell volume and solvent-accessible void space show significant variation. In particular, 4 and 5 show an enlarged and skewed unit cell, which can be attributed to a specific inter­action between an N - CH3 group in the solvent mol­ecule and the toluene group of cele­coxib. Inter­molecular inter­action energies calculated using the PIXEL method show that the total inter­action energy between the cele­coxib and solvent mol­ecules is broadly correlated with the mol­ecular volume of the solvent, except in 6, where the increased polarity of the S=O bond leads to greater overall stabilization com­pared to the similarly-sized DMF mol­ecule in 1. In the structures showing disorder, the most stable orientations of the solvent mol­ecules make C - H⋯O contacts to the S=O groups of cele­coxib.