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, C18H15ClN2O2S} have been synthesized and characterized by single-crystal X-ray diffraction; these are etoricoxib–benzoic acid (1/1), C18H15ClN2O2S·C7H6O2 (ETR–Bz), etoricoxib–4-fluoro­benzoic acid (1/1), C18H15ClN2O2S·C7H5FO2 (ETR–PFB), and etoricoxib–4-nitro­benzoic acid (1/1), C18H15ClN2O2S·C7H5NO4 (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.