Preferential Crystallization (PC) is a popular process to separate enantiomers, however the nucleation and growth of the counter enantiomer during the process can compromise the enantiopurity of the final crystalline product. This research investigates the use of additives to inhibit the nucleation and growth of the counter enantiomer. In this study, we use Lasparagine monohydrate (L-Asn•H2O) as the preferred enantiomer in crystallization from DLAsn•H2O solutions. Additives include both pure enantiomers of several related amino acid species. This allows investigation of differences in inhibition caused by additives that are of the same chirality and different chirality as the preferred enantiomer. The additives had no discernible effect on the solubility but had a small effect on the metastable limit, with additives tending to slightly widen the metastable zone but also make the zone widths more

Preferential crystallization (PC) is a process to separate enantiomers. The efficiency of seeded, isothermal PC was enhanced using tailor‐made additives to inhibit the crystallization of the counter‐enantiomer. The inhibition of D‐asparagine (D‐Asn) monohydrate using D‐glutamic acid (D‐Glu) and D‐aspartic acid (D‐Asp) as additives in PC was investigated by comparing the purity, yield, and particle size distribution after PC of L‐Asn·H2O from DL‐Asn·H2O. The amount of pure L‐Asn·H2O solid product that can be produced before crystallization of the counter‐enantiomer is higher when using the additives D‐Asp and D‐Glu. However, the crystal size of L‐Asn·H2O increases faster in PC without additives than in PC with additives. This means that the additives inhibit not only the crystallization of D‐Asn·H2O but also the crystal growth of L‐Asn·H2O.

Antisolvents increase the supersaturation in the crystallization process which can enhance the product yield. The effect of an antisolvent on the solubility of g-DL-methionine (g-DL-met) in aqueous solution was investigated. The solubility of g-DL-met was measured with various binary solvent mixtures. It improved with higher temperature but decreased with increasing the antisolvent mass fraction. Acetone showed the highest efficiency to reduce the solubility. The solubilities were correlated with the van't Hoff-Jouyban-Acree model and the modified Apelblat-Jouyban-Acree model. Both models fitted to the experimental results with high accuracy. Enthalpy, entropy, and Gibbs free energy of dissolution were determined by van't Hoff analysis. The thermodynamic properties indicated that the dissolution process is endothermic and entropy-driven.

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Among lanthanide-based compounds, cerium compounds exhibit a significant role in a variety of research fields due to their distinct tetravalency, high economic feasibility, and high stability of Ce(IV) complexes. Herein, a systematic investigation of crystallographic information, chemical properties, and mechanistic formation of the novel Ce(IV) complex synthesized from cerium(III) nitrate hexahydrate and 2,2′-(methylazanediyl)bis(methylene)bis(4-methylphenol) (MMD) ligand has been explored. According to the analysis of the crystallographic information, the obtained complex crystal consists of the Ce(IV) center coordinated with two nitrate ligands and two bidentate coordinated (N-protonated and O,O-deprotonated) MMD ligands. The fingerprint plots and the Hirshfeld surface analyses suggest that the C–H⋯O and C–H⋯π interactions significantly contribute to the crystal packing. The C–H⋯O and C–H⋯π contacts link the molecules into infinite molecular chains propagating along the [100] and [010] directions. Synchrotron powder X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) techniques have been employed to gain an understanding of the oxidative complexation of Ce(IV)-MMD complex in detail. This finding would provide the possibility to systematically control the synthetic parameters and wisely design the precursor components in order to achieve the desired properties of novel materials for specific applications.