The new solid forms screening of sulfamethazine was conducted in 16 kinds of different pure solvents. Four new sulfamethazine solvates were reported for the first time, and three crystal structures of solvates were successfully determined from single-crystal X-ray diffraction data. The results showed that sulfamethazine solvate formation directly depended on the solvents used in the experiments. The solvent properties were used to evaluate the effects of solvent on solvate formation. It was found that the H-bond acceptor ability of the solvent was the main factor that governed the solvate formation. The H-bonded motifs in the structures of solvates have been fully characterized. The results revealed that sulfamethazine solvate formation was mainly driven by molecular self-assembly through hydrogen bonding between solvent and solute molecules. Meanwhile, the crystal structures results also showed that the sulfamethazine molecule had flexible conformation. Furthermore, the principles of different sulfamethazine molecules packing in different crystal structures were discussed from the view of molecular intermolecular interactions and the molecular conformation.

•Solubility of erythromycin ethylsuccinate in organic solvents were determined.•The solubility data were correlated by modified Apelblat, van't Hoff, Wilson, and NRTL model.•The mixing properties were calculated based by Non-random two liquid (NRTL) model.•The solubility behavior of erythromycin ethylsuccinate were illustrated by Hansen SPs values.The solid-liquid equilibrium data of erythromycin ethylsuccinate in six pure organic solvents including tetrahydrofuran, acetone, acetonitrile, hexane, ethanol and 2-propanol were determined by using the gravimetric method over the temperature range from 288.15 K to 323.15 K. The experimental solubility data was correlated by modified Apelblat equation, van't Hoff, Wilson, and NRTL model, among which the modified Apelblat model was found to have the best agreement with the experimental results. The mixing Gibbs free energy, mixing enthalpy, and mixing entropy were calculated by Non-random two liquid (NRTL) model. The solubility behavior of EES at given temperature were illustrated by Hansen SPs values.

A new hydrate of sulfadiazine calcium (Hydrate I) was discovered, and the crystal structure was determined using single crystal X-ray diffraction. Both channel-type water (9.23 wt %) and calcium-ion coordinated water (11.87 wt %) existed in the unit cell. The thermal stability and dehydration of Hydrate I were investigated by thermal gravimetric analysis, hot stage microscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. A two-step dehydration process was detected from Hydrate I to anhydrous phase (AP) with the intermediate of the less-hydrated form (Hydrate II). The dehydration kinetics of Hydrate I with both channel-type and coordinated water was studied using model fitting method and model free method in isothermal mode. The dehydration activation energy was derived via the Friedman method. Further, the first-step dehydration of Hydrate I was determined to be the 2D phase boundary reaction mechanism, and the second-step dehydration was found to be 3D phase boundary reaction mechanism via model fitting approach.

•Solubility of thiourea in methanol + ethanol and methanol + propanol was studied.•Experimental and calculated (NIBS/R-K) data are in a good agreement.•Interaction between solute and solvent are calculated by Molecular simulation.•Thermodynamic properties of both dissolving and mixing process are calculated.The solubility data of thiourea in methanol + ethanol mixtures and methanol + n-propanol mixtures were determined from T = (283.15 to 313.15) K by gravimetric method under atmospheric pressure. Effects of solvent composition and temperature on solubility of thiourea were discussed. Molecular simulation results indicate that solubility of thiourea will be influenced by interaction energy and a quantitative conclusion can be drawn from the modeling result. To extend the applicability of the solubility data, experimental solubility data in two kinds of binary solvent mixtures were correlated by the modified Apelblat equation, λ–h equation and (NIBS)/Redlich–Kister model. It was found that all the three models could satisfactorily correlate the experimental data and the (NIBS)/Redlich–Kister model could give better correlation results. Furthermore, thermodynamic properties of dissolving and mixing process of thiourea, including the enthalpy, the Gibbs energy and the entropy, were also calculated and analyzed.

The crystal structures of form A and form B of 2,3,5-trimethyl-1,4-diacetoxybenzene (TMHQ-DA) were elucidated for the first time by using the single crystal X-ray diffraction method. It was found that form A and form B can be distinguished by different space group of P21/c and P21/n, respectively, although both of them belong to monoclinic crystal system. The methyl groups on the benzene ring of TMHQ-DA molecule in form B crystal lattice are disordered over four positions, with occupancies of 0.600(3) and 0.900(3) at C2 and C3 and the same at their symmetric location (C2a and C3a), while there is not any position disorder observed in the crystal structure of form A. Several offline analytical tools, such as scanning electron microscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and solid-state 13C NMR spectroscopy, were used to further characterize the crystal structures of these two polymorphs. The solvent-mediated polymorphic transformation of the enantiotropic polymorphs of TMHQ-DA was investigated in detail. Raman, FTIR, and FBRM were used to in situ monitor the transformation processes. It was found that the polymorphic transformation processes between TMHQ-DA polymorphs can be controlled by different steps at different stage of the whole process. To further understand the mechanism of the transformation and to find out how to control it, the effects of solvent, temperature, seeding, and amount of solid loading on the transformation behavior were investigated in detail. The influence mechanism was also analyzed.

The solubilities of the homologous series of dicarboxylic acids, HOOC–(CH2)n−2–COOH (n = 2–10), in water have been measured at temperatures ranging from 288.15 to 323.15 K by a static analytic method at atmospheric pressure. Dicarboxylic acids with even numbers of carbon atoms exhibit lower solubilities than acids with adjacent odd carbon numbers. The odd–even effect of solubility is most likely associated with the twist of the molecules, which influences the molecular packing in the solid state: the molecules stack with some offset in the cases of even (n = even) series, but without offset in the cases of odd (n = odd) series, whereas the carboxyl groups are twisted in even members. The interlayer packing is looser in odd members than that in even ones. The energies of intramolecular torsion were calculated using Materials studio 6.0 (Accelrys Software Inc.). Finally, the molar Gibbs energies were predicted, which also showed odd–even alternation.

In this article, the nucleation process of cefodizime sodium was analyzed from two perspectives: induction time and hydrogen-bond formation. According to classical nucleation theory, the correlation of the induction time indicated that heterogeneous nucleation dominates the nucleation process at lower supersaturation whereas homogeneous nucleation is the main mechanism at higher supersaturation. Then, in situ Raman spectroscopy was used to investigate the probability of hydrogen-bond formation in the supersaturated solution and the nucleation process of cefodizime sodium. A central feature of the hydrogen bonding is that the probability reaches a maximum value at the nucleation point, which can be used to relate the probability of hydrogen-bond formation to the induction time. Furthermore, SEM imaging affords fundamental information to illustrate the effect of supersaturation on the morphology of cefodizime sodium crystals: agglomerated small needlelike particles preferentially formed at a high supersaturation, whereas large needlelike particles formed at low supersaturation.

The solubilities of 5-amino-N,N′-bis(2,3-dihydroxypropyl)-2,4,6-triiodobenzene-1,3-dicarboxamide in ethanol + water mixtures at temperatures from (318.15 to 353.15) K were measured. The experimental data were correlated with the Apelblat model. The calculated values of Apelblat model were found to show a fine representation of the experimental data.

The solubilities of pravastatin sodium of form A in aqueous 2-propanol mixtures from (278 to 323) K were measured. A laser monitoring observation technique was used to determine the dissolution of the solid phase in the solid + liquid mixtures. The experimental data were correlated with a semiempirical equation.

The solubilities of pravastatin sodium of form B in (water + 2-propanol) from (278 to 323) K were measured. A laser-monitoring observation technique was used to determine the dissolution of the solid phase in the solid + liquid mixtures. The experimental data were correlated with a semiempirical equation.

Polymorphic transformation of pravastatin sodium in a mixture of isopropanol and water was studied by use of online focused beam reflectance measurement (FBRM) and particle vision measurement (PVM). It is shown that the form A polymorph transformed to the stable polymorph, form B. It was speculated that in the transformation process there was an agglomeration and breakage phenomenon. The transformation mechanism was identified as solution-mediated phase transformation. Influences of temperature, solvent composition, and stirrer speed on the transformation process were examined. It can be seen from the FBRM monitoring results that higher temperature, larger ratio of water to isopropanol, and higher stirrer speed can increase the transformation process.

The solubility data of adefovir dipivoxil in five different binary mixed solvents formed by isopropyl ether with ethanol, 2-propanol, dichloromethane, ethyl acetate, and acetone at 298.15 K were measured with the mole fraction of isopropyl ether ranging from 0.000 to 1.000. A laser monitoring observation technique was used to determine the dissolution of the solid phase in a solid + liquid mixture. The solubility data were correlated with a function of the binary solvent mole fractions by the combined nearly ideal binary solvent (NIBS)/Redlich–Kister equation.

The solubility of losartan potassium in mixed 2-propanol + water and 2-propanol + cyclohexane solvents was measured at the temperature ranging from (293.15 to 343.15) K under atmospheric pressure. The experimental data were correlated by the CNIBS/Redlich–Kister model. The results show that the solubility of losartan potassium increases with increasing temperature in these two binary mixed solvents and increases with the increasing mole fraction of water while decreasing mole fraction of cyclohexane, respectively.

The solubility of 2-butyl-4-chloro-1-[[2′-tetrazol-5-yl)-biphenyl]-4-yl]methyl-5-(hydroxymethyl) imidazole potassium in pure methanol, ethanol, 1-propanol, 2-propanol, 1-pentanol, ethyl acetate, butyl acetate, and cyclohexane was measured by a synthetic method over the temperature range from (293.15 to 343.15) K under atmospheric pressure. The experimental data were correlated by the modified Apelblat model. The results show that the solubility of losartan potassium increases with the increasing temperature in pure methanol, ethanol, 1-propanol, and 2-propanol and decreases with the increasing temperature in 1-pentanol. It is also found that losartan potassium is sparingly soluble in ethyl acetate, butyl acetate, and cyclohexane, and the solubility in these three solvents varys little with the temperature.

The solubilities of pravastatin sodium in water, methanol, ethanol, 2-propanol, 1-propanol, and 1-butanol from (278 to 333) K were measured. A laser monitoring observation technique was used to determine the dissolution of the solid phase in the solid + liquid mixture. The experimental data were correlated with a semiempirical equation. The solubilities in the six solvents decrease in the following order: water > methanol > ethanol > 1-propanol > 1-butanol > 2-propanol.