Supramolecular interactions in cocrystals of benzoic acid derivatives with selective COX-2 inhibitor etoricoxib.

The structures of three 1:1 cocrystal forms of etoricoxib {ETR; systematic name: 5-chloro-2-(6-methylpyridin-3-yl)-3-[4-(methylsulfonyl)phenyl]pyridine, C ₁₈ H ₁₅ ClN ₂ O ₂ S} have been synthesized and characterized by single-crystal X-ray diffraction; these are etoricoxib-benzoic acid (1/1), C ₁₈ H ₁₅ ClN ₂ O ₂ S·C ₇ H ₆ O ₂ (ETR-Bz), etoricoxib-4-fluorobenzoic acid (1/1), C ₁₈ H ₁₅ ClN ₂ O ₂ S·C ₇ H ₅ FO ₂ (ETR-PFB), and etoricoxib-4-nitrobenzoic acid (1/1), C ₁₈ H ₁₅ ClN ₂ O ₂ S·C ₇ H ₅ NO ₄ (ETR-PNB). Powder X-ray diffraction and thermal differential scanning calorimetry-thermogravimetry (DSC-TG) techniques were also used to characterize these multicomponent systems. Due to the influence of the corresponding acids, ETR shows different conformations. Furthermore, the energetic contributions of the supramolecular motifs have been established by energy framework studies of the stabilizing interaction forces and are consistent with the thermal stability of the cocrystals.