The surface chemistry of colloidal cesium lead bromide (CsPbBr3) nanocrystals is decisive in determine the stability and the final morphology of this class of material, characterized by ionic structure and a high defect tolerance factor. Here, the high sensitivity of purified colloidal nanocubes of CsPbBr3 to diverse environmental condition (solvent dilution, ageing, ligands post synthetic treatment) in ambient atmosphere is proved thanks to a comprehensive morphological (electron microscopy), structural ( /2 XRD and GIWAXS) and spectroscopic investigation. In particular, we establish the ability of aliphatic carboxylic acids and alkyl amines ligands to induce, even in a post preparative process at room temperature, structural, morphological and spectroscopic variations.Upon addition of oleyl amine the highly green emitting CsPbBr3 nanocubes effectively turn into 1D thin tetragonal nanowires or lead halide deficient rhombohedral 0D Cs4PBBr6 structures with a completely loss of fluorescence. On the other hand, addition of oleic acid induces the transformation of nanocubes into still emitting orthorombic 2D nanoplates, with tunable thickness/lateral size,

Preferential crystallization is a cost efficient method to provide pure enantiomers from a racemic mixture of a conglomerate forming system. Exploiting small amounts of pure crystals of both enantiomers, several batch or continuous processes were developed, capable of providing both species. However, an intermediate production step has to be used when pure enantiomers are not available. In such cases, partially selective synthesis, chromatography, or crystallization processes utilizing chiral auxiliaries have to be used to provide the initial seed material. Recently, it was shown that a coupled Preferential Crystallization-selective Dissolution process (CPCD) in two coupled crystallizers can be applied if at least one pure enantiomer is available to produce both antipodes within one batch. The corresponding process is carried out in one reactor (crystallization tank) by seeding a racemic supersaturated solution with the available enantiomer at a certain temperature. The second reactor (dissolution tank) contains a saturated racemic suspension at a higher temperature. Both reactors are coupled via the fluid phase, allowing for a selective dissolution of the preferentially crystallizing enantiomer from the solid racemic feed provided in the dissolution vessel. The dissolution and crystallization processes continue until the solid racemic material is completely resolved and becomes enantiopure. At this point, both enantiomers can be harvested in their pure crystalline form. For a specific pharmaceutically relevant case study, a rational process design and the applied empirical optimization procedure will be described. The achieved productivities after optimization show the great potential of this approach also for industrial applications. Also, a strategy to control this process based on inline turbidity measurement will be presented.

Ternary phase diagrams are essential research tools in several scientific fields. They provide fundamental understanding and guidance in designing separation experiments. While their utility and relevance is undisputed in the chemical and chemical engineering community, yet much progress remains to be done in understanding and exploiting ternary phase diagrams for crystallization-based chiral separation purposes. A guide in the interpretation of the ternary solubility phase diagram of a chiral molecule to design the separation of its enantiomers is provided. On the basis of the discussion of fundamental relationships in the phase diagram, basic enantioseparation experiments are performed for D-/L-methionine in water exploiting the characteristic shift of the eutectic composition in the chiral system. The rational approach followed in separation process design is described together with the experimental procedures applied and the results obtained.

Viedma deracemization is based on solution phase racemization, dissolution of racemic or scalemic conglomerates and crystal growth through autocatalytic cluster formation. With rate limiting racemization, its acceleration by appropriate catalysts may result in speeding up deracemization. A conglomerate‐forming chiral compound may principally racemize directly, or via reverse of its formation reaction. For a hydrazine derivative, we investigated available racemization pathways in presence of pyrrolidine or thiourea amine as base catalysts: via Mannich or aza‐Michael reaction steps and their reverse, or by enolization. Racemization by enolization was computationally found to dominate, both under water‐free conditions and in presence of water, involving a multitude of different pathways. Faster racemization in presence of water resulted indeed in more rapid deracemization, when the base was pyrrolidine. Under water‐free conditions, the role of water as enolization catalyst is assumed by chiral hydrazine itself – in autocatalytic racemization and in which both reactant and product are catalysts.