AbstractPotassium alunite is a potential mineral resource of potassium and aluminum that can serve as a valuable resource. An effective potassium and aluminum recovery method is developed using gradient leaching with a KOH sub‐molten salt. The key part of this process is seeded precipitation of the potassium aluminate leach solution. Therefore, this study aims to optimize the seeded precipitation process by investigating the effects of alkali concentration, molecular ratio, stirring rate, temperature, and seed coefficient on the precipitation ratio and particle size of Al(OH)3. The results show that alkali concentration, molecular ratio, temperature, and seed coefficient are key factors influencing seeded precipitation. Furthermore, the process is optimized by using these four identified factors as variables. A 9L(34) orthogonal experiment determines optimal conditions for maximizing the precipitation ratio and achieves the desired average particle size. Under the optimal condition of 200 g L−1 alkali concentration, 1.5 molecular ratio, 1.0 seed coefficient, and 343.15 K temperature, the precipitation ratio reaches 54% and the average Al(OH)3 particle size is 114 µm. Further work is required to scale up this optimized seeded precipitation process and evaluate applications of the Al(OH)3 product.

AbstractThe low‐dimensional organic‐inorganic lead halide compound has garnered significant attention in recent times due to its exceptional optoelectronic properties. However, its application in the field of optoelectronics has been hindered by the toxicity of lead. Here, a novel inorganic‐organic compound [Epy]2[CuBr3] single crystal material with a 0D structure based on Cu(I) is introduced. The single crystal exhibits a broad band yellow luminescence, a significant Stokes shift, and a microsecond‐scale photoluminescence (PL) lifetime, which is mainly attributed to the self‐trapped excitons (STEs) excitation. In addition, the relevant PL spectra are measured at 78–348 K. The photoluminescence intensity decreases with increasing temperature due to strong electro‐phonon coupling. The exciton binding energy Eb of the crystal is 76.43 meV, and the Huang‐Rhys factor S is 40.55. It is worth noting that the crystal also shows a good response to X‐rays. Overall, [Epy]2[CuBr3] displays its good potential.

AbstractOiling‐out is a common phenomenon in industrial crystallization processes that not only prolongs the total operating time but also leads to undesirable crystal morphology, making it challenging to control crystallization paths. This review provides a comprehensive overview of the oiling‐out phenomenon in organic small molecule crystallization. First, the formation mechanisms of oiling‐out are summarized from both thermodynamic and dynamic perspectives, providing the theoretical foundation for understanding the phenomenon. Then, the universal characterization methods for studying the oiling‐out phenomenon of organic small molecules are introduced in detail, covering both offline and online analytical tools. Moreover, the regulation strategy for oiling‐out, including solvents, impurities, seeding, temperature, and mixing methods are discussed. This paper also focuses on the application of oiling‐out in co‐assembly and crystal shape modulation. Finally, future opportunities and challenges are presented to address the current shortcomings and application bottlenecks in the study of organic small molecule oiling‐out phenomena. This review aims to provide valuable insights and guidance for researchers working on the crystallization of organic small molecules, particularly in the pharmaceutical industry, to better understand, control, and utilize the oiling‐out phenomenon.

AbstractA recent interest attaches to the derivatives of the (2‐benzylsulfinyl)benzoic acid as inhibitors of human carbonic anhydrases (hCAs), an action that can be applied in innovative therapies. A set of crystal structures of six sulfides and six enantiopure sulfoxides related to this scaffold, taken from the literature, or derived from the work on the asymmetric synthesis of sulfinyl compounds, is investigated. The lattice energies of these structures are estimated by means of the Crystal Explorer 21 program. The weak interactions building up the crystal structures are identified, and their contributions are analyzed in comparison with the calculated lattice energies. The most stable conformations in the solid phase are identified. It is worth observing that the sulfides of the scaffold under investigation behave almost in the same manner; on the other hand, the presence of the sulfinyl group of the sulfoxides adds complexity, that shall be taken into account in future docking calculations of these molecules with the hCAs enzymes.

AbstractAspirin, a commonly used pharmaceutical therapeutic pharmacological substance, exhibits cross‐nucleation (intergrowth or overgrowth) of stable polymorphic Form‐I over the preferably required metastable polymorphic Form‐II, which creates a bottleneck issue in the solution crystallization of aspirin in most organic solvents and their mixtures. Controlling the overgrowth phenomenon is a key factor for designing the pharmaceutical drug material aspirin with desired properties. Hence, our present work chose a novel template‐assisted swift cooling crystallization with selected templates like copper‐wire and nylon 6/6 polymer, and also N‐N‐Dimethylformamide (DMF) as a solvent. The pure solution in the absence and the presence of a nylon 6/6 template in all the experimental supersaturation ranges achieves only thermodynamically stable polymorphic Form‐I of aspirin with slightly different morphologies. Contrarily, the presence of a copper‐wire template induces both stable and metastable polymorphs of aspirin depending on the level of supersaturation in the mother solution. The effect of templates on the nucleation kinetics of aspirin polymorphs is estimated using classical nucleation theory, and the determined values exactly match with experimental results. The polymorphic nature of the grown crystals is ascertained by powder X‐ray diffraction (PXRD), single crystal X‐ray diffraction (SCXRD), and differential scanning calorimetry (DSC) analyses.