Existing core–shell structured metal–organic frameworks (MOFs) are typically constructed by epitaxial growth with metal or/and organic ligands (the two basic components for MOFs) changing from core to shell, whereas in this contribution, we propose a new concept for constructing core–shell structured MOF featuring hierarchic encapsulation of various guest molecules into the framework. The cyclodextrin metal–organic frameworks (CD-MOFs) were chosen as the host to encapsulate organic dyes for light-emitting applications, and the cavity structure of γ-cyclodextrin and cage structure of MOF exhibited remarkable synergistic effects on fluorescence enhancement. Furthermore, core–shell structured CD-MOFs with hierarchical encapsulation of different dyes were developed to realize polychromatic light emitting via spectrum superposition. On the basis of this new method, we further fabricated a white-light emitting core–shell crystal, CD-MOF⊃7-HCm@FL@RhB (shell@core). With three sequentially formed and adjustable layers of different dyes, the core–shell crystal emitted bright white light with a CIE coordinate of (0.35, 0.32). Our approach provides a new method for the rational design of multicolor emission crystals. Meanwhile, our findings may stimulate future investigations on multifunctional host–guest systems in crystalline state.

The solubility of dipyridamole p-toluene sulfonate in seven monosolvents (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, isobutanol, 2-butanol) and three different binary solvents (methanol + ethanol, methanol + 1-propanol, methanol + 1-butanol) was measured by a gravimetric method at temperatures ranging from 288.15 to 328.15 K. The experimental results indicate that the solubility of dipyridamole p-toluene sulfonate increases with increasing temperature while showing negative correlation with the mole fraction of organic solvents (ethanol, 1-propanol, 1-butanol) at a given temperature in binary solvents. The Apelblat model, the CNIBS/R-K model, and the modified version of Jouyban-Acree models (the Apel-JA equation) were used to correlate the experimental data, and the calculated results of above models were found to agree well with the experimental data.

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Spherulitic growth, categorized as central multidirectional growth and unidirectional growth via small-angle branching, has increasingly been explored as a method to improve the flowability and bulk density of needle-like crystals. However, the formation of two categories of spherulites in solutions is still unclear. In this work, the formation mechanism of two categories of spherulite was studied in a supercooled nitroguanidine (NQ) aqueous solution with a small amount of gelatin. It is proposed that spherulitic growth depends on the initial morphology of the crystallite, wherein the gelatin concentration, temperature, and initial supersaturation play a vital role. Gelatin can significantly inhibit NQ nucleation, promote branching, and modify the morphology of NQ subunits. At high initial supersaturation and low temperatures, the aspect ratio of the crystal precursor increases and branching is accelerated, so that the lateral faces provide more branching sites than the end faces to promote the unidirectional growth. In comparison, high temperatures promoting the multipoint branching should be mainly responsible for the formation of cauliflowerlike spherulites. Furthermore, the bulk densities of the cauliflower-like and compact spherulites of NQ are about triple those of needle-like crystals and their evolutions were observed. Compared with the reported methods, the macromolecule-induced spherulitic growth of NQ without an organic solvent is a green method and will have a bright future for the design and fabrication of other organic spherulites.

The solid–liquid equilibrium data of l-carnitine fumarate in methanol + (ethanol/1-propanol/2-propanol) binary mixed systems were determined at temperatures ranging from 288.15 to 328.15 K, while the solubility data of l-carnitine fumarate in (methanol +1-butanol) mixtures were determined from T = (293.15 to 333.15) K because of its low solubility in low temperature. All experimental data were obtained by the gravimetric method under atmospheric pressure. At each composition point, the data increases with the increasing temperature in all determined solutions. A similar trend is also observed when the mole fraction of methanol increases in all binary solvent mixtures for each temperature. It is also found that the solubility data of l-carnitine fumarate in these binary mixtures rank as (methanol + ethanol) > (methanol +1-propanol) > (methanol +2-propanol) > (methanol +1-butanol). The modified Apelblat equation, (CNIBS)/Redlich–Kister model, Solubility–Polarity model, and Jouyban–Acree model were employed to correlate the solubility data determined, and all of them show good agreement with experimental value. Furthermore, the crystal morphology and size distribution of l-carnitine fumarate in different solvents was studied in order to select favorable solvents for good crystal habits.

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Synthesis and visible-light photocatalytic N2/H2O to ammonia at atmospheric pressure and room temperature is considered to be the most ideal ammonia synthesis technology. In this study, coal-based carbon dots (CDs) were prepared by H2O2 oxidation method using cheap and ubiquitous coal as the carbon source. Then the gold sol was connected to CDs to obtain a core-shell structure photocatalyst Au@CDs by sodium borohydride (NaBH4) reduction method. While characterizing the material structure, the photocatalytic N2/H2O to ammonia performance of Au@CDs was investigated. The results show that the introduction of CDs in Au @CDs photocatalysts can not only improve the performance of the catalyst to excite carriers in visible light, but also inhibit the recombination of photogenerated electron-hole pairs, promote the charge transport ability and make photogenerated electrons and holes move smoothly to the catalyst surface. Meanwhile, the adsorption and dissociation capacity of N2 on the catalyst surface can be improved, thereby the photocatalytic N2/H2O ammonia synthesis reaction of Au@CDs can proceed smoothly.