Latest ArticlesThe deterioration of water caused by industrial production is a thorny problem. Solving the problem cogently through innovative coagulationstrategies has been recognized of important practical significance. In this work, a simple enhanced coagulation by using ferric chloride (FC) and poly-ferric chloride (PFC) coupled with polyamidine (PA) were tried to remove the toxic organics. The results shown that PA addition could obviously enhance coagulation performances of the iron-based coagulants. The synergic coagulation process and mechanism were studied and discussed in detail based on the coagulation behaviors, flocs properties, removal efficiency and zeta potentials. FC and PFC remove organics mainly through charge neutralization and adsorption-bridging, resulting in a good purification performance. While PA with a higher charge density showed better purification performance due to enhanced charge neutralization. It is worth mentioning that the addition of PA could make the coagulants adapt to a wider pH range, and remove the toxic organics more effectively. That is to say, the practical adaptability of the coagulant was enhanced. This work thus provides a simple strategy to effectively purify wastewater and further improve the water safety.
Recognized as one of the important active species involved in various reactions, singlet oxygen (1O2) shows potential applications in chemical, biological, and environmental related fields. However, the controlled capture and release of 1O2 are still facing huge challenges due to its short lifetime and high reactivity. Herein, a framework-interpenetration tuning strategy was applied on a metal-organic framework (MOF) that aiming to improve the capture and release rate of 1O2. The porosity of the MOF was remarkably enhanced with the structural evolution from seven-fold (termed NKM-181) to six-fold interpenetration (termed NKM-182), and the active anthracene sites became much more accessible. Such drastic process can be achieved as simple as exchanging the primitive MOF in selected solvent and occurred surprisingly as single-crystal to single-crystal transformation. Also, additionally owing to the unblocked regular channels, NKM-182 shown significantly improved 1O2 trapping and releasing rates compared to that of in NKM-181. This work demonstrates an unprecedented regulation of 1O2 capture and release process, along with achieving the highest 1O2 capture and release rate among reported porous materials. Furthermore, the obtained endoperoxides with 1O2 loaded (termed EPO-NKM-181 and EPO-NKM-182) can be used as a high efficiency smart material for anti-fake application
Following our previous work on human immunodeficiency virus-1 (HIV-1) non-nucleoside reverse transcriptase inhibitors (NNRTIs), a series of novel biphenyl-pyridone derivatives were synthesized and evaluated for their anti-HIV-1 activity to expand their structure–activity relationship. Some of them exhibited low nanomolar activity toward wild-type HIV-1 and clinically relevant single/double mutant strains. The most active compound B1 was 231-fold more potent (EC50 = 17 nmol/L) than the lead compound 2 (EC50 = 3.93 µmol/L) against wild-type (WT) HIV-1. This compound was approximately 3.5-fold less cytotoxic (CC50 = 100.58 µmol/L) than compound 2 (CC50 = 28.24 µmol/L), presenting a higher selectivity index (SI) value of 5923. Compared with 2, the antiviral potency of B1 was significantly increased against five single mutant strains (L100I, K103N, E138K, Y181C and Y188L) and two double mutant strains (F227L+V106A and K103N+Y181C). Especially, K103N, Y181C and K103N+Y181C were more sensitive to B1 than both 2 and doravirine. Besides, the enzymatic inhibitory activity of B1 against wild-type HIV-1 reverse transcriptase was approximately 32-fold higher (IC50 = 100 nmol/L) than 2 (IC50 = 3.21 µmol/L). Molecular docking studies and dynamic simulations were conducted to explain their potent activity. Taken together, this research represents an important step toward the discovery of novel biphenyl-pyridone drug candidates for HIV therapy.
Carbon is a promising capacitive electrode material for Zn-ion hybrid supercapacitors (ZHSCs), as it is low-cost, environmentally friendly, controllable and adjustable. By now, achieving both high energy and high power with carbon electrodes is still challenging, limited by their intrinsic properties. In this work, we have designed and presented an amorphous hollow carbon bowl material with surface chemical modifications of oxygen groups to figure out these concerns. The preparation of bowl-like structures and the storage behavior between Zn2+ and oxygen functional groups have also been discussed. With the contributions from its unique hollow structure and surface functional groups, it can significantly enhance the electrode pseudocapacitance and the entire electrochemical performance.
Because of abundant redox activity, broad tunability, and specific atomic structure, polyoxometalates (POMs or POM) clusters have attracted burgeoning interests in electrochemical especially energy storage fields. Nevertheless, due to the high solubility and fully oxidized state, they often suffer from electrically insulation as well as chemical and electrochemical instability. Traditional noncovalent loading or covalent grafting of POMs on conductive substrates have been successfully performed to overcome this problem. However, severe shedding or agglomeration of POMs arising from weak interactions with substrates or excessive entrapment or weak destruction in conductive supports cause significantly reduced availability and stability. To this end, precise confinement of POMs into conductive supports has been tried to improve their dispersibility and stability. Herein, recent progress of POMs from surface loading to precise confinement in the electrochemistry energy storage field is reviewed. Firstly, we illustrate the typical non-confinement methods (viz. covalent and non-covalent) for supported POMs in energy storage applications. Secondly, different strategies for precise confinement of POMs in organic and inorganic materials for related applications are also discussed. Finally, future research directions and opportunities for confined POMs, and derived ultrafine nanostructures are also proposed. This review seeks to point out future research directions of supported POMs in the electrochemistry-related fields.
A photocycloaddition reaction of ethyl 1,4-diaryl-1,4-dihydropyridine-3-carboxylate for the construction of 3,9-diazatetraasteranes (P1) and 3,9-diazatetracyclododecanes (P2) is reported for the first time. The types of reaction product clearly differ with solvent, regardless of the irradiation wavelength. The difference in P1 and P2 lies in the second step of the intramolecular [2 + 2] photocyclization. In order to further investigate this phenomenon and gain a deeper understanding of the photochemical behavior of 1,4-dihydropyridines, DFT and TDDFT theoretical calculations are performed. The results provide a good explanation for the formation of 3,9-diazatetraasteranes and 3,9-diazatetracyclododecanes.
Two-dimensional organic-inorganic hybrid ferroelastics with high-temperature reversible phase transitions are very rare and have become one of the research hotspots in the field of ferroelastic materials. Herein, we report three new layered organic-inorganic hybrid perovskites based on halogen-substituted phenethylaminium, (3-XC6H5CH2CH2NH3)2[CdCl4] (X = F (1), Cl (2) and Br (3)). They undergo structural phase transitions at 376/371 K, 436/430 K, and 421/411 K, respectively, between the isomorphic high-temperature phases (space group I4/mmm, Z = 2) and different room-temperature phases with the reduced structural symmetries, i.e., P21/a (Z = 2) in 1, (Z = 4) in 2, and P21/a (Z = 4) in 3, respectively. These ferroelastic transitions arise from the order-disorder transition of organic cations together with the synchronous displacement of inorganic layers, accompanying with ferroelastic spontaneous strains of 0.16, 0.13 and 0.12 for 1−3, respectively. By enriching layered perovskite ferroelastics based on halogen-substituted cations, this work provides important clues for exploring new ferroic materials based on hybrid crystals.
Direct synthesis of glycerol carbonate (GC) from CO2 and glycerol (a byproduct of biodiesel production) is a route to obtain a high-value chemical from waste and low-cost byproducts but has not yet industrialized due to the lack of efficient catalysts. Ceria (CeO2) exhibits the highest catalytic activity and GC selectivity among the heterogeneous catalysts studied so far. However, the mechanism of this reaction over CeO2 catalysts has not been studied in detail. Herein, we synthesized CeO2 nanocrystals with different morphologies as model catalysts that can predominantly expose {111}, {110}, and {100} facets, and their surface acid-base properties were characterized using high-sensitivity temperature-programmed desorption of NH3 and CO2 with quadrupole mass spectrometry as detector (NH3-TPD-QMS and CO2-TPD-QMS). We found that the catalytic performance (GC formation rate) is strictly linearly dependent on the density of basic sites, which is relevant to the adsorption and activation of CO2. In addition, to illustrate a more microscopic reaction mechanisms underlying the formation of GC from CO2 and glycerol on all three low-index surfaces (111), (110) and (100), we also performed comprehensive first principles calculations. A three-step Langmuir–Hinshelwood (LH) mechanism was identified in which the annulation reaction is the rate-limiting step. The CeO2 (111) surface exhibits the lowest overall activation energy, which agrees well with the catalytic performance that the CeO2 nano-octahedra, predominantly exposing {111} facets, have the highest GC formation rate. This work is the first to combine experiments on shaped CeO2 model catalysts with first-principles calculations to gain insight into the mechanism of direct synthesis of GC from CO2 and glycerol, and will aid in the development of catalysts with improved performance.
Superlattices in crystals, particularly in perovskite oxides with strong correlation effects, can create new states of matter and produce peculiar physicochemical phenomena. However, the newfangled perovskite superlattices depend on physical deposition with unit-cell precision. It has been challenging to explore a new suitable chemical method to tailor perovskite superlattices. Herein, we present a new bottom-up strategy to precisely prepare atomic-scale oxide superlattices of (LaMnO3)1-(La1-x-yCaxKyMnO3)2 in a monodispersed perovskite La0.66Ca0.29K0.05MnO3 (LCKMO). The special atomic-scale perovskite superlattices are demonstrated using SAED, HAADF-STEM, XRD, and atomic-resolution elemental mapping. Our experiments reveal that the perovskite superlattices can be fabricated under extreme hydrothermal conditions utilizing ultra-high concentrations of KOH. An approximate molten salt system in the hydrothermal process can induce the disproportionation reaction of MnO2 solids, which is vital to the growth of ordered perovskite superlattices. This work not only clarifies the hydrothermal growth process of perovskite oxides in extreme conditions, but also proposes a novel engineering route toward perovskite superlattices.
A novel BINOL-based fluorescence probe (S)-6 featuring a sodium sulfonate fragment at the 2′-position was designed and synthesized via simple synthetic procedures under mild reaction conditions. The water-soluble probe (S)-6 displays excellent enantioselective recognition toward 15 common amino acids, and it can be used for enantiomeric excess determination of amino acids. The fluorescence intensity of (S)-6 treated with amino acids reaches the maximum after standing for only 30 min at room temperature and remains stable in the following 5.5 h, which has great potential in the application of chiral fluorescence analysis due to its timeliness and outstanding fluorescent stability.
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