Latest ArticlesAn efficient asymmetric and enantio-swithchable organocatalytic[3 + 3] annulation reaction using MBH-2-naphthoates of nitroalkenes and 4-hydroxyquinolin-2(1H)-ones has been developed. Densely substituted tetrahydropyrano[3, 2-c]quinolinones scaffolds with two adjacent stereogenic centers are obtained with high yield (up to 95% yield) and good stereoselectivities (up to > 20:1 dr and 96% ee) in an enantio-switchable manner. Furthermore, gram scale synthesis was achieved and the nitro group could easily transform into an amino group without any appreciable loss in the diastereo-and enantioselectivity.
Recent development of self-healing material has attracted tremendous attention, owing to its biomimetic ability to restore structure and functionality when encountering damages. Here, we develop a threedimensional (3D) printable self-healing composite conductive polymer by mixing hydrogen-bond-based supramolecular polymer with low-cost carbon black. It has a room-temperature self-healing capability in both conductivity and mechanical property, while its shear-thinning behavior enables fabrication of a self-healable circuit by 3D printing technology. As an application, the circuit shows an excellent temperature-dependent behavior of the resistance, indicating its great potential for practical application in the artificial intelligence field.
Considering the importance and complexity of benzene oxidation on mineral oxide aerosol surfaces in the atmosphere, gas-phase 3d-transition metal oxide cations were used as models of active sites on mineral oxide aerosols to mimic the corresponding reactions. The various cations have been prepared by laser ablation and reacted with benzene in a linear ion trap reactor. Of the 103 systematically investigated cations, 39 clusters can oxidize benzene at room temperature. In addition to the adsorption channel, other five types of reaction channels were observed, including dehydrogenation of C6H6, charge exchange, hydrogen atom transfer, oxygen atom transfer, and the formation of C6H5O·radical, among which the first two pathways are prevalent and the formation of C6H6O+ cations has not been reported in literature. The insight into the benzene oxidation reactions derived from the gas-phase model systems is helpful to build a detailed picture of oxidative mechanisms of C6H6 and its derivatives over corresponding mineral oxide aerosols.
In this work, the protic ionic liquid [DBUH] [Im] (1, 8-diazabicyclo[5.4.0]-7-undeceniumimidazolide) was developed as an efficient catalyst for the transesterification of ethylene carbonate with methanol to produce dimethyl carbonate. At 70 ℃, up to 97% conversion of ethylene carbonate and 91% yield of dimethyl carbonate were obtained with 1 mol% [DBUH] [Im] (relative to ethylene carbonate) as catalyst in 2 h. Even at room temperature, the conversion of ethylene carbonate can reach 94% and the yield of dimethyl carbonate can approach 81% for 6 h. Catalytic mechanism investigation showed the high catalytic efficiency of this ionic liquid results from the synergistic activation effect, wherein the cation can activate ethylene carbonate and the anion can activate methanol through hydrogen bond formation. Although the reusability of the ionic liquid need to be further improved, high efficiency and commercial availability of [DBUH] [Im] render it a promising catalyst for the preparation of dimethyl carbonate.
Electronic polarization has an important impact on the site energies of charge carriers that play a key role in determining the charge transport in organic semiconductors. Dipolar molecules have strong intermolecular interactions and widespread applications in organic optoelectronics. However, compared with nonpolar organic semiconductors, electronic polarization for dipolar systems has been rarely studied. Here, taking 1, 2, 3, 4-tetrafluoro-6, 7-dimethylnaphthalene as representative, we have calculated the electronic polarization energies of dipolar organic molecular crystals by means of a polarizable forcefield method. Surprisingly, our results point to that the polarization energies for this dipolar system are similar to those of nonpolar systems. In addition, the π-π stack contributes only about 30%~40% to the total polarization energy, thus the polarization effects along the three dimensions should be treated equally even for the one-dimensional stacking crystals.
A series of novel phenylpyrazole carboxylic acid derivatives containing fluorine moiety, i.e., diamides 11, simple aryl-bearing amides 12 and acylthioureas 14 were successfully synthesized based on the key fluoro-containing phenylpyrazole acid intermediate. The new compounds were identified and confirmed by melting point, 1H NMR, 13C NMR and elemental analysis or HRMS. The bioassay results indicated that some of the compounds possessed excellent insecticidal activities towards oriental armyworm, diamondback moth and corn borer at low concentrations. For examples, compounds 11a, 11e-g and 14b exhibited remarkable larvicidal activities with LC50 values of 0.13-0.39 mg/L and 0.0002-0.0014 mg/L against oriental armyworm and diamondback moth, respectively, were comparable with those of the control chlorantraniliprole. Particularly, 11e were found superior to chlorantraniliprole in oriental armyworm tests (LC50:0.23 mg/L vs. 0.26 mg/L); 11a, 11e, 11f and 14c in diamondback moth tests with LC50 values of 0.0002 mg/L, 0.0002 mg/L, 0.0008 mg/L and 0.0005 mg/L, respectively, were more effective than that of chlorantraniliprole. In addition, 12a also showed a promising insecticidal potential and development/optimization advantage. Compounds 11a, 11e-g, 12a, 14b and 14c could be considered as possible new leading structures for further study. The SAR investigation indicated that the compounds with fluorine motif (e.g., -F, -CF2H, -CF3) held apparently favorable insecticidal potentials, which provided useful guidance for further design/development of new phenylpyrazole-containing agrochemicals.
Spirooxindoles play an important role in drug discovery and development. The development of efficient methods for the synthesis of spirooxindoles from easily available starting materials is of current interest. Herein, we report in detail the In(OTf)3-catalyzed [3 + 3] annulation of spirocyclopropyl oxindoles and 1, 4-di-thiane-2, 5-diol, which allows the facile preparation of spiro[indoline-3, 4'-thiopyran]-2-ones bearing (tetrahydro)thiopyran skeleton.
Silicon (Si) materials as anode materials for applications in lithium-ion batteries (LIBs) have received increasing attention. Among the Si materials, the electrochemical properties of SiOx-based (0 < x ≤ 2) composites are the most prominent. However, due to the cycling stability of SiOx being far from practical, there are some problems, such as low initial coulombic efficiency (ICE), obvious volume expansion and poor conductivity. Researchers in various countries have optimized the electrochemical properties of SiOx-based composites by means of pore formation, surface modification, and the choice of constituents. In this review, SiOx-based composites are classified into three categories based on the valency of Si (SiO2 composites, SiO composites and SiOx (0 < x < 2) composites). The synthesis, morphologies and electrochemical properties of the SiOx-based composites that are applied in LIB are discussed. Finally, the properties of several common SiOx-based composites are briefly compared and the challenges faced by SiOx-based composites are highlight.
Metal-organic frameworks (MOFs) are a class of outstanding materials in Li-air batteries because of their high surface areas, tailorable pore sizes and diverse catalytic centers. However, MOF-based batteries are facing challenges such as poor electronic conductivity and inferior long-cycle stability that limit their further development. This review first summarizes the progress of pristine MOFs and MOF-derived materials in Li-air batteries in the past 5 years, then provides a perspective for subsequent development of MOFs and their derivatives in this emerging field.
The lithium metal battery has been considered as a promising candidate for next generation batteries. However, safety concerns caused by uncontrollable lithium dendrite growth on lithium anode are severely hampering the commercial application. Metal-organic frameworks (MOFs) become one of the most attractive materials due to the high porosity, structural designability and tunability. With unique open channels and pores as well as functional components in MOFs, the transportation and deposition of lithium ions can be regulated, which leads to enhanced electrochemical properties. Various strategies for lithium metal protection are proposed in recent works on applications of MOFs in lithium metal batteries. In this review, we highlight latest key approaches in this field and discuss the prospects for MOFs in advanced Li anodes.
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