Exploring the effect of magnetic field on crystallization process and revealing the mechanism of magnetic field can enrich the regulation and intensification methods of crystallization process. In this paper, the effect of magnetic field on crystal nucleation and growth and its mechanism were comprehensively studied from the perspective of crystallization thermodynamics and kinetics, using a small organic molecule polyamide 56 salt as the model compound. The solubility, nucleation kinetics, and growth kinetics of the polyamide 56 salt were measured in the absence and presence of magnetic field, respectively. It was found that the magnetic field can improve the solubility of the model compound. The introduction of magnetic field can result in solubilization effect and enhance the directional motion of particles which can weaken the solute−solvent interaction. In addition, the introduction of magnetic field will prolong the nucleation induction period, widen the metastable zone width, and increase the nuclear barrier, which is the result of the competition between the directional motion of particles induced by the magnetic field and the inherent random Brownian motion. Moreover, the magnetic field can also effectively affect the crystal morphology and particle size, which is the result of the synergistic effect of nucleation kinetics and growth kinetics.

To better understand the thermodynamics and molecular self-assembly mechanism of diastereomeric salt/cocrystalinduced chiral separation, a series of 1:1 cocrystals and salts consisting of chiral valines (VAL) and tartaric acid derivatives were synthesized via different methods. Powders of these as-screened cocrystals/salts were characterized by PXRD, TGA, DSC, FT-IR, and Raman spectroscopy. The crystal structures of the five cocrystals/salts were determined and analyzed. It was found that both DBTA and DTTA form diastereomeric salt pairs with VAL enantiomers. Interestingly, L-DMTA cocrystallizes with D-VAL and L-VAL via hydrogen bonding and proton transfer, respectively. Considering this particularity, the differential isothermal (10 °C) ternary phase diagrams (TPDs) of D-DMTA and L-VAL (D-VAL) cocrystals (salt) were constructed in the mixed solvent of MeOH/ H 2 O. Moreover, a pure L-VAL:D-DMTA cocrystal and D-VAL:D-DMTA:0.5CH 4 O:0.25H 2 O salt were prepared via equimolar slurry conversion at 10 °C. In situ Raman spectroscopy was applied to monitor the molecular assembly process during the incubation of the cocrystal/salt. Molecular dynamics simulation was employed to rationalize the molecular recognition mechanism, demonstrating the excellent chirality preference of L-DMTA toward L-VAL instead of D-VAL. Calculations of density functional theory approved the synergistic instead of antagonistic effects of binding energy and solvation free energy toward chiral separation.

The formation of a conglomerate is always attractive, which is a prerequisite for chiral resolution by a flexible and productive preferential crystallization. This present study is aimed at exploring the possibility of chiral resolution in a two racemic compound system. The racemic conglomerate of S–S and R–R was prepared by slurring RS-naproxen (RS-NAP) with RS-1-(2-naphthyl) ethylamine (RS-NEA), which was determined by powder X-ray diffraction, differential scanning calorimetry, single-crystal X-ray diffraction, and ternary solubility phase diagram. Moreover, comparative analysis of the molecular structure, stacking patterns, thermodynamic properties, and intermolecular interactions of S–S and R–S indicates that the S–S crystal is more stable. Finally, the feasibility of chiral resolution in isopropanol was explored through a seeded isothermal preferential crystallization mode, and alternative crystallization of S–S and R–R was achieved with recycling the mother liquors.

The stability of solvates is very important in the field of crystal engineering. Molecular interaction and packing mode are important factors affecting the stability of solvates. In this study, 2,7‐dibromo‐9H‐carbazole is selected as the model compound to investigate the influence of molecular stacking mode on the stability of solvates. An anhydrous form and five solvates of 2,7‐dibromo‐9H‐carbazole are obtained by recrystallization. The desolvation phenomena of the five solvates are studied by thermogravimetric analysis, hot stage microscope, and infrared spectroscopy and it is found that the stability of the solvates is N,N‐dimethylacetamide solvate > dimethyl sulfoxide solvate > N,N‐dimethylformamide solvate > dioxane solvate > acetonitrile solvate. Crystal structures are analyzed by single crystal X‐ray diffraction and Hirshfeld surface analysis is also applied to analyze the intermolecular interactions in the crystals. The results show that the stability of the five solvates is related to the packing modes of the molecules in the crystal. It is suggested that the solute molecules and solvent molecules in the unstable solvates are arranged in the interlayer mode, while they are arranged in a staggered mode in stable solvates.