9 research outputs found

    Determination and Correlation of Solubility of Cefradine Form I in Five Pure Solvents from (283.15 to 308.15) K

    No full text
    The solubility of cefradine form I in five pure solvents from (283.15 to 308.15) K was experimentally determined by using an equilibrium method. It was found that the solubility of cefradine form I in all tested solvents increased with the increase of temperature. Four thermodynamic models were used to correlate the experimental solubility data. The infinite-dilution activity coefficient and mixing properties including the mixing free Gibbs energy, enthalpy, and entropy of cefradine form I solution were also calculated by using the nonrandom two-liquid (NRTL) model. It was found that the correlated results by the van’t Hoff equation, the modified Apelblat equation, and the NRTL model agreed well with the experimental data

    Experimental Determination and Computational Prediction of Androstenedione Solubility in Alcohol + Water Mixtures

    No full text
    This article evaluates the accuracy and applicability of three of the most common solubility models (i.e., Jouyban–Acree, NRTL-SAC, and COSMO-RS) in prediction of androstenedione (AD) solubility in binary mixtures of methanol + water and ethanol + water. The solubilities were measured from (275 to 325) K using medium-throughput experiments and then well represented mathematically by modified Apelblat and CNIBS/Redlich–Kister equations. The computational results show that AD solubility decreases monotonically with increasing water concentration in methanol + water mixtures, but it has a maximum at 0.15–0.30 mole fraction of water in the ethanol aqueous solution. Moreover, the performance of three solubility prediction models in this particular case was compared to identify the advantages and disadvantages of each model. The overall average relative deviation (ARD) for solubility prediction is 4.4% using Jouyban–Acree model, while it is 18.3% with NRTL-SAC model. Surprisingly, COSMO-RS model in combination with reference solubility achieves a good performance for solubility prediction in mixed solvents, including the prediction of synergistic effect of solvents, with overall ARD of only 4.9%

    Flexible Optical Waveguides in Heterocyclic Schiff Base Self-Assembled Hydrogen-Bonded Solvates

    No full text
    Flexible fluorescent crystalline materials exhibit both mechanical and optical properties and have received great attention due to their potential applications in flexible optical devices. Simultaneously adjusting the mechanical and optical properties of crystalline materials remains interesting and challenging. In the present work, a guest molecule was introduced via hydrogen-bonded solvation, which achieved excellent mechanical elasticity and higher fluorescence emission than that of the host heterocyclic Schiff base molecule crystal itself. The crystal structure–property relationship and the molecular mechanism of the elasticity were then investigated in detail. It revealed that solvent molecules play a key role in changing both the stacking of fluorescent molecules and the interaction energy framework. In addition, the flexible fluorescent solvate exhibits a good waveguide property. A bent crystal was found to have a larger optical loss coefficient than a straight crystal. Furthermore, the size effect on the optical loss coefficient of the waveguide was discussed in which the optical loss coefficient decreases as the sizes increase. Such a size effect is usually neglected in waveguide material research and should be complemented in the performance evaluation of optical waveguides

    Flexible Optical Waveguides in Heterocyclic Schiff Base Self-Assembled Hydrogen-Bonded Solvates

    No full text
    Flexible fluorescent crystalline materials exhibit both mechanical and optical properties and have received great attention due to their potential applications in flexible optical devices. Simultaneously adjusting the mechanical and optical properties of crystalline materials remains interesting and challenging. In the present work, a guest molecule was introduced via hydrogen-bonded solvation, which achieved excellent mechanical elasticity and higher fluorescence emission than that of the host heterocyclic Schiff base molecule crystal itself. The crystal structure–property relationship and the molecular mechanism of the elasticity were then investigated in detail. It revealed that solvent molecules play a key role in changing both the stacking of fluorescent molecules and the interaction energy framework. In addition, the flexible fluorescent solvate exhibits a good waveguide property. A bent crystal was found to have a larger optical loss coefficient than a straight crystal. Furthermore, the size effect on the optical loss coefficient of the waveguide was discussed in which the optical loss coefficient decreases as the sizes increase. Such a size effect is usually neglected in waveguide material research and should be complemented in the performance evaluation of optical waveguides

    Solution-Mediated Polymorphic Transformation of Prasugrel Hydrochloride from Form II to Form I

    No full text
    In situ Raman spectroscopy was applied for the analysis of the solution-mediated polymorphic transformation of prasugrel hydrochloride from the metastable form II to the stable form I. The solution concentration during the transition process was monitored by a gravimetric method. The main factors studied were solvent, temperature, solid loading, and agitation speed. Because of the balance between the solubility and the strength of solute–solvent interactions, the transformation rate was highest in ethyl acetate and lowest in butanone at all three temperatures studied (20, 30, and 40 °C). The thermodynamic driving force of the polymorphic transformation from form II to form I was evaluated through solubility measurements of the two forms in ethyl acetate, acetone, and butanone. At increasing temperature, the nucleation induction time and the overall transformation time decreased despite the decreasing driving force. The solid loading seemed to have no effect on the transformation time because of surface nucleation of form I on form II, as determined from the morphology–time profile through polarizing microscope analysis, whereas increasing the agitation rate resulted in a faster polymorphic transformation process. It was confirmed by transformation experiments that the polymorphic transformation from form II to form I is controlled by the nucleation and growth of the stable form I crystal

    Solid–Liquid Phase Equilibria of Ternary Mixtures Containing 1,2‑Dihydroacenaphthylene and Dibenzofuran

    No full text
    Ternary phase diagram data of 1,2-dihydroacenaphthylene-dibenzofuran mixtures in a series of alcohols, including methanol, ethanol, propan-2-ol, propan-1-ol, butan-1-ol, and pentan-1-ol were measured using a dynamic method at 308.15 and 313.15 K. The experimental data were correlated with the Wilson model (including pseudobinary systems), UNIQUAC model, and NRTL model. The results indicate that pseudobinary systems with the Wilson equation give a better description of the solubility of the ternary system. The eutectic point shifts toward dibenzofuran when the more polar methanol and ethanol are used. This shift may help achieve a more efficient separation of 1,2-dihydroacenaphthylene and dibenzofuran

    Concomitant Polymorphism of Prasugrel Hydrochloride in Reactive Crystallization

    No full text
    Concomitant polymorphism of prasugrel hydrochloride was investigated in reactive batch crystallization experiments at 20 and 40 °C. The solubility of prasugrel hydrochloride form I and form II was experimentally determined. To understand the effects of reaction kinetics, supersaturation ratio, and nucleation kinetics on the behavior of concomitant polymorphism of prasugrel hydrochloride and the solvent-mediated transformation process, online techniques such as attenuated transform reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, Raman spectroscopy, and focused beam reflectance measurement (FBRM) were used to in situ monitor the reactive crystallization of prasugrel hydrochloride. It was found that prasugrel and hydrochloric acid react promptly and the designed supersaturation can be established almost instantly. The interfacial energies and thus relative nucleation rates of prasugrel hydrochloride form I and form II were calculated, and it was concluded that, at all investigated supersaturations, the nucleation rate of form II is always higher than the nucleation rate of form I. At lower supersaturation, thermodynamics dominated the crystallization process and form I was obtained, while at higher supersaturation, kinetics was critical in the crystallization process and form II was produced. At moderate supersaturation, both thermodynamics and kinetics played important roles and concomitant polymorphism of form I and form II was observed. Solvent-mediated transformation experiments were performed with and without seeding. It turns out that the transformation cannot happen without seeding of form I. Therefore, not reaction kinetics and polymorphic transformation but the concomitant nucleation should be the inherent reason for the observed concomitant polymorphism

    Preparation and Dehydration Kinetics of Complex Sulfadiazine Calcium Hydrate with Both Channel-Type and Coordinated Water

    No full text
    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

    Preparation and Dehydration Kinetics of Complex Sulfadiazine Calcium Hydrate with Both Channel-Type and Coordinated Water

    No full text
    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
    corecore