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The purification of isomer monomers with high purity is extremely important, particularly in the fine chemical industry, pharmaceutical industry, and so on. Herein, a selective cocrystallization (SCoC) technology based on non-covalent interactions between the target compound and cocrystal conformers was developed to effectively separate isomer mixtures. The unique and efficient selectivity nature of conformers and the general applicability of the selective cocrystallization method was tested through separating and purifying cresol isomer mixtures, pyridinecarboxamide isomer mixtures, and cis−/trans-butenedioic acid mixtures. Moreover, the nature of selective recognition to cocrystallize was confirmed both in the solution and solid states. Thus, this study demonstrates the feasibility of this novel SCoC technology, which is a new method for separating isomer mixtures.

A novel method for the Rh(III)-catalyzed oxime-directed C–H amidation of indoles with dioxazolones has been developed. This strategy provides an exclusive site selectivity and the directing group can be easily removed. This transformation features a wide substrate scope, good functional group tolerance and excellent yields, and may serve as a significant tool to construct structurally diverse indole derivatives for the screening of potential pharmaceuticals in the future.

To investigate the effect of positional isomerism on cocrystallization and reveal the role of weak interactions in the formation of cocrystals, experimental characterization complemented with theoretical computations was thoroughly conducted by using p-hydroxybenzoic acid (PHBA), o-hydroxybenzoic acid (OHBA), m-hydroxybenzoic acid (MHBA) and malonic acid (MA) as model compounds. Selective formation of a new cocrystal was discovered between PHBA and MA molecules via several methods, while no cocrystal was formed between OHBA/MHBA and MA molecules. The PHBA–MA cocrystal was thoroughly characterized and analyzed through several solid characterization techniques such as powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) analysis, Fourier transform infrared (FTIR) spectroscopy, single crystal X-ray diffraction (SCXRD), etc. Taking advantage of a myriad of computational modelling techniques, the molecular recognition mechanism which drove the formation of cocrystals was comprehensively investigated and understood at a molecular level. The structural change accompanied by the cocrystal formation could be rationalized by FTIR spectroscopy and electron density variation analysis. Hirshfeld surface (HS) analysis indicated that O–H⋯O hydrogen bonds played a critical role in the formation of this cocrystal. Molecular electrostatic potential (MESP) surface analysis was employed to predict the interaction sites for cocrystallization, which were in good accordance with the experimental results. Moreover, possible reasons for the selective cocrystallization were analyzed and proposed.

To gain further insights into the formation of cocrystals, the thermodynamic mechanism and molecular recognition process of cocrystal formation were investigated by using p-hydroxybenzoic (PHBA) as the model compound. One new 1 : 1 (molar ratio) cocrystal of p-hydroxybenzoic (PHBA) and glutaric acid (GA) was successfully synthesized via several methods, including liquid-assisted grinding, cooling crystallization, and slurry conversion crystallization. The prepared cocrystal powder was characterized by PXRD, DSC and Raman spectroscopy. The crystal structure of the cocrystal was determined and interpreted by single-crystal XRD. The ternary phase diagrams of the newly prepared cocrystal were constructed in acetonitrile at three temperatures, i.e., 2, 20 and 40 °C. The temperature was shown to have an impact on the shape of the ternary phase diagrams. Guided by the determined ternary phase diagrams, the pure PHBA–GA cocrystal could be prepared successfully by isothermal slurry conversion crystallization. Raman spectroscopy was employed to monitor the molecular recognition and self-assembly process of the conversion in situ. In addition, density functional theory calculations were conducted to determine the stability and interaction energy of the cocrystal, rationalizing the formation potential of the PHBA–GA cocrystal.

An efficient and simple method, depositing nano iron oxide onto the surface of Pd/SiO2, to construct sintering-resistant Pd nanocatalysts was presented. The introduction of nano iron oxide not only promoted the sintering-resistance of Pd nanoparticles, but also increased the boundary between the Pd and iron oxide. The resultant catalysts exhibited enhanced catalytic activity for aerobic oxidation of benzyl alcohol.