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Ionic liquids enable highly efficient Knoevenagel reaction by dual-responsive emulsion microreactor
No full textKnoevenagel condensation reaction is important for generating C-C double bonds and providing various valuable intermediates in organic chemistry, which always need harsh conditions including high reaction temperature, difficult catalyst recovery, difficult product separation, etc. In this work, a novel class of dual -responsive emulsion reactor was prepared for the Knoevenagel condensation reaction between malononitrile and aromatic aldehyde, where the temperature and CO2-responsive ionic liquids (ILs) were used as an emulsifier, responder, and catalyst simultaneously. Driven by temperature or CO2, the emulsion reactor undergoes reversible and controllable transformations between emulsification and demulsification, where efficient catalytic reactions, product separation, and reactor recovery are all achieved. The isolated product yield of 2-(4-chlorobenzylidene)-malononitrile remained above 90% after 5 cycles of the emulsion reactor. NMR and molecular dynamics simulations showed that the temperature drives the reversible stretching and curling of the polyether chain on the cation, while CO2 reacts with the -COO- group on the anion to form carbonates and carboxylic acids in water, leading to changes in the surface activity of ILs, thereby reversibly regulating the demulsification and emulsification of the emulsion. Hence, through the dual stimuli-responsive ILs, the efficient reaction can be performed in the homogeneous phase, and the products and catalysts can be easily separated in the heterogeneous phase. These results on the revisable microreactor can not only help to design the smart and efficient "homogeneous reaction-heterogeneous separation " systems but also support the development of green sustainable chemistry
Preparation, characterization, and physicochemical property of the inclusion complexes of Cannabisin A with ,B-cyclodextrin and hydroxypropyl- ,B-cyclodextrin
No full textCannabisin A (CA), derived from hemp seed shells, has antioxidant and anti-neuroinflammatory activity. However, its application is limited due to its poor solubility. In this work, ,B-cyclodextrin ( ,B-CD) and HP-,B-cyclodextrin (HP -,B-) were used to encapsulate CA to increase its water-solubility. The inclusion complexes of CA with ,B-CD (CA/,B-CD IC) and the inclusion complexes of CA with HP -,B-CD (CA/HP-,B- CD IC) were prepared by the aqueous ethanol solution method. The Job's plot assay and Phase solubility assay revealed that the inclusion complexes of CA with ,B-CD/HP-,B-CD formed at a 1:1 stoichiometric ratio. However, considering the inclusion process is reversible, the inclusion complexes were prepared at a 1:2 molar ratio. The structure of the inclusion complexes was identified by FT-IR, XRD, DSC, SEM, and NMR. In addition, the results of1 H NMR, 2D ROESY NMR, and molecular docking further determined the possible conformations of the inclusion complexes. The solubility of the CA in the CA/,B-CD IC and CA/HP-,B-CD IC was increased by 13.95-fold and 56.37-fold, respectively, compared to pure CA; and the dissolution and antioxidant activity of the CA were also significantly promoted after complexation. This study proved that CA/HP-,B-CD IC was the preferred inclusion complex compared to CA/,B-CD IC due to its better physicochemical properties. (c) 2022 Published by Elsevier B.V
Construction of a flower-like SnS2/SnO2 junction for efficient photocatalytic CO2 reduction
No full textPhotoreduction of CO2 to value-added chemicals and fuels is an attractive solution to alleviate environ-mental problems and energy crisis at the same time. However, engineering efficient photocatalysts with high activity and product selectivity is still challenging. Herein, we achieved three-dimensional (3D) spa-tial configuration design at micro-scale and heterogeneous interface construction at nano-scale on a SnS2/SnO2 composite, which featured hierarchical flower-like morphology consisted of nanosheets and type-II semiconductor structure. It behaved excellent selectivity and impressive photocatalytic CO2-to-CO performance with a yielding rate of 60.85 lmol g-1h-1, roughly 3 times higher than that of SnS2 and was in the front rank of this kind catalysts under 300 W Xe lamp illumination without using any sen-sitizers or noble metals. The enhanced catalytic capability could be attributed to the elaborately built structure with suitable energetic position that afforded effective separation and migration of photo -generated electron/hole pairs as well as enhanced light caption and absorption. Meanwhile, main reactive intermediates (e.g., CO2- and *COOH) were captured by in-situ Fourier transform infrared spectroscopy (FTIR), suggesting a fluent catalytic pathway on the SnS2/SnO2 platform. This work provides a new scheme to build advanced catalysts based on multiscale design and rational phase assembling.(c) 2022 Elsevier Inc. All rights reserved
Mortise-tenon joints reinforced Janus composite solid-state electrolyte with fast kinetics for high-voltage lithium metal battery
No full textBilayer composite solid-state electrolytes (CSSEs) are regarded as promising candidates to meet the requirements of high-voltage lithium metal batteries due to their exceptional compatibility with both opposite electrodes. However, such a configuration usually leads to additional interfacial impedance between CSSEs and discontin-uous Li+ migration process, resulting in deteriorated electrochemical performances. Herein, a Janus electrolyte with mortise and tenon joints (JCSSE) is proposed for enhancing interfacial compatibility. It is composed of poly (vinylidene fluoride-co-hexafluoropropylene)(P(VDF-HFP))/Li6.4La3Zr1.4Ta0.6O12layer toward cathode and poly (diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide (PDADMATFSI)/UiO-66-SO3Li layer to Li-metal anode. Such a configuration enables not only intimate contact between the two electrolyte layers, but regulated Li+ coordination environment which would improve Li+ transference number. Both simulation and experimental characterization suggest that the defluorinated-P(VDF-HFP) with low highest occupied molecular orbital (HOMO) and PDADMATFSI with strong adsorption energy toward lithium metal can favor the formation of stable electrode/electrolyte interface. Optimized JCSSE exhibits a high ionic conductivity of 0.21 mS cm-1 at 25 degrees C and a wide electrochemical window of 5.0 V. As a result, Li//JCSSE//LiNi0.8Mn0.1Co0.1O2 battery could deliver remarkable cycling performances at 4.3 V for 100 cycles. In addition, JCSSE enables superior cyclability from 25 to 100 degrees C. High-voltage pouch cells employing JCSSE exhibit unexpected endurance under harsh conditions. This novel Janus electrolyte with tenon and mortise structure will accelerate the commercialization of high-energy -density lithium metal batteries
Molten-salt-mediated synthesis of Na+ doped Bi4TaO8Cl nanosheets with exposed {001} facets for enhanced photocatalytic degradation
No full textRegulating the exposed surfaces of semiconductors is believed to be a versatile strategy to boost their photoactivity. Herein, the Na+ doped Bi4TaO8Cl (BTOC) nanosheets with the exposed {001} active faces were synthesized via a facile molten salt method. The size of BTOC nanosheets could be readily tuned by con-trolling the feeding content of the molten salts (NaCl and KCl). Benefited from the cooperative effect of the Na+ doping and the exposed active {001} facets, the optimal BTOC-24 nanosheets exhibited high photo activity. Under 5 W white LED light irradiation, the degradation rates of BTOC-24 nanosheets for ofloxacin (OFL) and Rhodamine B (RhB) were 84.1% and 97.3%, which were drastically enhanced by 2 and 6-folds than that of bulk BTOC, respectively. The mechanism for the improved photoactivity was also investigated. This work demonstrates the synergetic effect of engineering the thickness and exposed crystal face towards the enhanced photoactivity of 2D BTOC, which also shows significant implications for designing other 2D semiconductor nanosheet with efficient environmental remediation performance. (c) 2022 Elsevier B.V. All rights reserved
