Density, surface tension, interfacial tension with water, and contact angles on Teflon and glass surfaces of 21 ionic liquids based on functionalized imidazolium, ammonium, phosphonium, and guanidinium cations combined with several anions, such as chloride, tetrafluoroborate, bis(trifluoromethanesulfonyl)imide, dicyanamide, p-toluenesulfonate, and ethylsulfate, were completely measured. The structure−property relationship of the selected ionic liquids was considered in order to predict their potential applications. Particularly relevant were the lower surface tension values (at 293.15 K) observed for tetrahexyldimethylguanidinium dicyanamide, [(di-h)2dmg][DCA] (21.35 ± 0.03 mN·m−1), and trioctylmethylammonium bis(trifluoromethanesulfonyl)imide, [Aliquat][NTf2] (22.77 ± 0.05 mN·m−1), and the remarkably low contact angles on Teflon surfaces of [(di-h)2dmg][DCA] (39.66°) and trihexyltetradecylphosphonium p-toluenesulfonate, [P6,6,6,14][p-TsO] (39.77°).

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Herein we report the synthesis of novel ionic liquids( ILs) and organic salts by combining ibuprofen as anion with ammonium, imidazolium, or pyridinium cations. The methodology consists of an acid-base reactiono fn eutral ibuprofen with cation hydroxides, which were previouslyp repared by anion exchange from the correspondingh alide salts with Amberlyst A-26(OH). In comparison with the parent drug, these organic salts display higher solubility in water and biological fluids and as maller degree of polymorphism, which in some cases was completely eliminated. With the exceptiono f [ C 16 Pyr][Ibu] and [N 1,1,2,2OH1 ][Ibu],t he prepared salts did not affect the viabilityo f normalh uman dermalf ibroblasts or ovarian carcinoma (A2780) cells. Therefore, these ibuprofen-based ionic liquids may be very promising lead candidates for the development of effective formulationso ft his drug.Ibuprofen is used in the treatmento fp aina nd inflammation in rheumatoid arthritisa nd other musculoskeletal disorders in both humans and animals. [1] It is considered one of the Essential Medicines by the World Health Organization( WHO). Ibuprofen is an onsteroidal anti-inflammatory drug (NSAID), which nonselectively inhibits cyclooxygenases 1a nd 2( COX-1a nd COX-2), resulting in the inhibition of prostaglandins. [2] Althoughi th as as trongera nalgesice ffect than other NSAIDs in some types of pain, [3] the mean onset of action per 400 mg dose is 45 minutes, which can be critical in an acute painsituation, where rapid relief is critical. [4] Its low solubility in the acidic aqueous media of the stomach is responsible for ibuprofen'ss low pharmaceutical effect, [5] despite its ease of permeability through the gastrointestinal membranes, rendering close to 100 %b ioavailability. [6] To increase the absorption rate and to provide faster pain relief, new formulations of ibuprofen have been developed over the years, particularly salts (sodium, [7] lysine, [8] and arginine [9] )a nd extrudate. [10] These forms, however,d on ot tackle the degree of ibuprofen's poly-morphism, [11] whose different crystal shapes display distinct pharmaceutical effects.For the last 10 years, ionic liquids (ILs) from active pharmaceuticali ngredients (APIs), or simply API-ILs, have been studied at the academic level, as the third generation of ILs. [12][13][14][15] ILs are salts with meltingt emperatures below 100 8C, with some of them being liquid at room temperature (RTILs), that result from the combinationoforganic cations with organic and inorganic anions. The scope of their physicala nd chemical properties has promptedt he study and application of these compounds in several areas of science and technology. [16] In the field of pharmaceutical sciences,w ea nd others have reported that the cation-anion interactions in the prepared API-ILs induce improved physicochemical properties over the original drugs, decrease toxicityt oward healthyc ells, and thus render potentially enhanced pharmaceutical activity to the API. [17][18][19][20][21][22] In more detail,s u...