Journal of The Chinese Chemical Society最新文献

CL-20/4,5-MDNI exists in two cocrystal forms with different stoichiometric ratios of 1:1 and 1:3. The properties (such as blast performance, thermal performance, sensitivity, and density) of the two cocrystals are significantly different, but both cocrystals are expected to become new high-energy insensitive explosives and have good applications. The AE model and molecular dynamics were used to simulate the crystal morphology and important crystal planes of 1:1 and 1:3 CL-20/4,5-MDNI under vacuum conditions, as well as in five solvents and different temperatures. 1:1 CL-20/4,5-MDNI has five main growth crystal planes of (002), (102), (111), (020) and (021), of which (002) has the largest proportion. 1:3 CL-20/4,5-MDNI has six main growth crystal planes of (001), (010), (011), (100), (101) and (111), of which (001) accounts for the largest proportion. The crystal morphology aspect ratio of 1:3 CL-20/4,5-MDNI in acetonitrile and 1:1 CL-20/4,5-MDNI in methanol are 1.936 and 1.680, respectively. The results were consistent with the experiments, which has certain guiding significance for CL-20/4,5-MDNI to obtain a crystal morphology closer to spherical shape.

Metal–organic framework (MOF) has attracted extensive attention in photocatalytic organic pollutants. However, most MOFs still have problems such as low response of visible light, easy recombination of electrons and holes, and complicated separation and recovery process. In this study, a facile approach was proposed to construct magnetic NH₂-MIL-53(Fe)/NiFe₂O₄ photocatalyst via solvothermal method. NiFe₂O₄ nanoparticles with octahedral structure are closely attached onto the surface of tubular such as NH₂-MIL-53(Fe). NH₂-MIL-53(Fe)/NiFe₂O₄ has soft ferromagnetism, good paramagnetism, and magnetic response. After 210 min visible light illumination, photocatalytic efficiency of NH₂-MIL-53(Fe)/NiFe₂O₄ reaches 95.71% in the condition of methylene blue (MB) concentration as high as 30 mg/L, which is much higher than that (50.11%) of NH₂-MIL-53(Fe). After five runs, photocatalytic activity of NH₂-MIL-53(Fe)/NiFe₂O₄ only decreases to 90.41%. Consequently, magnetic NH₂-MIL-53(Fe)/NiFe₂O₄ photocatalyst has huge potential applications in removing organic dyes by a green and environmentally friendly way due to its high photocatalytic activity, high stability, and easy solid–liquid separation.

As the main structural component of tobacco cell wall, lignin content is an important factor affecting the safety of tobacco smoking. However, it is time-consuming to quantify lignin by conventional wet chemical analysis methods. In this work, a ¹³C multiCP/MAS NMR spectral analysis method for tobacco lignin was established. The multiCP/MAS NMR sequence was optimized for tobacco lignin. The optimized nuclear magnetic sequence parameters were 9 CP cycles of 1.5 ms, repolarization time of 0.7 s, and a total acquisition time of 130 min. Subsequently, TMSP was used as the internal standard substance to establish the working curve, and the correlation coefficient was 0.9946. The relative standard deviation (RSD, n = 5) was 3.26%. This method was applied to the determination of lignin content in different types of tobacco samples. The relative error in the determination of lignin content by this method did not exceed 4.46% compared to the results of the chemical method. The results showed that the ¹³C multiCP/MAS NMR spectral analysis method had the advantages of accuracy and rapidity, which provided a new technical means for the quantitative study of tobacco cell wall substances.

Inspired by the strong adsorption of oil and moisture for the ashes of mosquito-repellent incense (MRI) in daily life, their potential application for the highly efficient separation of water-in-oil (W/O) and oil-in-water (O/W) emulsions was developed. Scanning electron microscopy (SEM) and energy spectrometer (EDS) were used to determine the micromorphology and composition of the MRI ashes. The packed ashes were both superhydrophilicity/superoleophilicity in the air, and underwater superoleophobicity/under-oil superhydrophobicity. Based on the special dual wettability of the ash layer, the resultant packed column was used for the efficient separation of O/W emulsions and the corresponding W/O emulsions, respectively. The separation flux of different types of O/W and W/O emulsions was over 2×10⁴ L/m²h and their separation efficiencies were maintained at over 95%. The waste MRI ashes without any physical and chemical treatment provided a new idea for the selection of efficient separation materials.

Focus of the figure: The photocatalytic degradation performance of biosynthesized nanoparticles for the eco-purification of pharmaceutical-polluted water was studied and demonstrated to be an economical remediation method with remarkable recyclability potential. Overall, the biogenic entities' oxygenated functional groups employed for nanoparticle biosynthesis contributed to the •OH and O2• dominance in the photocatalytic degradation operation. More details about this figure will be discussed by Dr. Stephen S. Emmanuel and his co-workers on pages 1332-1357 in this issue.

A comparative study of the Gd₂O₃:Tb and Y₂O₃:Tb nanoparticles (NPs) was presented to examine the influence of the host lattices on the crystallographic phase, surface characteristics, optical properties, Raman effect, and photoluminescence properties. Cubic shapes Gd₂O₃:Tb and Y₂O₃:Tb NPs with an estimated crystalline size of 17 and 11 nm were recorded from the X-ray diffraction pattern, respectively. Comparative absorption spectra of both oxides NPs were presented to examine the dispersibility, colloidal stability, and optical behavior of the NPs. Energy bandgap values were estimated to monitor the optical characteristics of the metal oxides in the UV/Vis region. Fourier transform infrared was recorded to confirm the surface-attached water and organic moieties. The Raman spectra of metal oxides were recorded to examine the symmetrical dis-order and polarizability of the vibrational bands. The ionic radius of the atoms distorts the bond structure resulting in it greatly influenced the vibrational bands of the materials. The emission spectra certified the effective doping of the luminescent Tb³⁺-ion in the metal oxide host lattices. Raman spectra and emission spectra validated the crystal symmetry imperfections; subsequently, the efficiency of the Raman active modes and emission transitions was greatly influenced. In a comparative analysis, Y₂O₃:Tb NPs exhibited higher luminescence intensity in comparison with the Gd₂O₃:Tb NPs.

Phosphine-mediated one-pot reactions have been developed that involve two mechanistically distinct reactions assembled in one reaction vessel via the sequential addition process. The first step involves MBH-type annulation of α,β-ynones to afford cyclic products in each case, which then engages in subsequent β-acylation or intramolecular Wittig reactions. The reaction conditions are mild and efficient, providing acylated alkylidene indandiones in 70%–99% yields or furo[2,3-f]dibenzotropones in 65%–91% yields, respectively.

Density functional theory (DFT) was used to study the mechanism of Diels–Alder (DA) reaction between 2-Methyl- 1,3 Butadiene (MBD) with B₁₂N₁₂, B₆N₆C₁₂ and B₆C₁₂N₆ fullerens in the gas phase. In this mechanism, B-N bonds of four-membered and six-membered rings of nanocages were chosen to react with MBD. Due to the existence of two types of B-N bonds, two competitive pathways (a and b) were investigated. The effect of the substitution of carbon atoms instead of boron and nitrogen atoms on the stability of the structures and the regioselectivity of the DA reaction was examined. The potential energy of all structures and the activation barrier for all reaction pathways was evaluated. The chemical reactivity of fullerens using the molecular quantum descriptors was assessed. To evaluate the global electron density transfer in transition states (TS) structures, the natural bond orbital (NBO) analysis was performed.