Synthesis and Characterization of a Series of Sulfamethazine Multicomponent Crystals with Various Benzoic Acids

Abstract

Nine multicomponent crystals consisting of sulfamethazine (sz) with benzoic acid and its derivatives were synthesized and characterized. Eight of the nine multicomponent crystals are cocrystals, while one is a molecular salt. The coformers used to form multicomponent crystals with sz include 2-chloro-4-nitrobenzoic acid (2c4n), 2-chloro-5-nitrobenzoic acid (2c5n), salicylic acid (2hba), 3-hydroxybenzoic acid (3hba), 4-hydroxybenzoic acid (4hba), 4-bromobenzoic acid (4Brba), benzoic acid (ba), cinnamic acid (ca), and toluic acid (ta). These multicomponent crystals were characterized by single-crystal X-ray diffraction (SC-XRD), powder X-ray diffraction (PXRD), and differential scanning calorimetry (DSC). SC-XRD showed that eight of the coformers that interacted with sz formed the amidine-carboxyl synthon; the only exception to this was sz + 4hba, which formed the imidine-carboxyl synthon formed instead. PXRD confirmed that the single crystals were representative of the bulk material. DSC showed most of the multicomponent crystals to have only a melting phase transition, which differed from the melting points of the coformers. The only exceptions were sz + 4brba and sz + ca, where an additional endothermic peak was observed, which corresponds to an amorphous phase transition before melting.

Influence of the pKa Value of Cinnamic Acid and P-Hydroxycinnamic Acid on the Solubility of a Lurasidone Hydrochloride-Based Coamorphous System

“…Crystalline LH showed its melting point around 260 °C, followed by a small thermal degradation peak (Figure a), which was the same as with our previous report . We found the fusion endotherms of pHCA and CA were 222.8 and 134.3 °C, respectively (Figure b,c), which were consistent with the reported results. , Moreover, it was observed that the physical mixtures of LH and CA exhibited two endothermic peaks, similar to their melting points (Figure S2a–c). However, the physical mixtures of LH and pHCA showed only one melting endotherm in the temperature range of 174–177 °C (Figure S2d–f), probably suggesting that a low eutectic mixture was formed between LH and pHCA.…”

Collecting the Molecular and Ionization States of Irbesartan in the Solid State

“…The first one is sulfamethazine. The amidine tautomer, imidine tautomer, anion, and cation have been observed in the structures of sulfamethazine and its crystalline complexes. − The other three APIs are piroxicam, meloxicam, and enrofloxacin, all of which showed the existence of neutral and zwitterionic molecular forms, as well as cationic and anionic states in reported structures. − For sulfamethazine, piroxicam, and enrofloxacin, the proton tautomeric sites are consistent with the protonation/deprotonation sites. Meloxicam shows a little difference.…”

Solid-state separation of hypoxanthine tautomers through a doping strategy

“…8,9 The solidstate separation of the tautomers of some tautomeric molecules has been achieved using this method. [10][11][12][13][14][15] New strategies should be developed to realize the solid-state separation of the tautomers of more tautomeric molecules. We proposed that the solid-state separation of the tautomers of the same molecules can be realized by doping the tautomeric molecules in an existing tautomeric polymorph or amorphous phase of their similar molecules with a definite tautomeric form which would induce them to dope with a certain tautomeric form.…”