Latest ArticlesWater-soluble pillar[5]arenes are a class of typical macrocycles and have aroused tremendous attention for its easy to modify, abundant host-guest properties and extensive applications. However, up to now, all the reported water-soluble pillar[5]arenes acted as the host molecules, whereas they failed to be postsynthetically modified, which seriously impeded the development of the pillar[5]arene-based supramolecular chemistry. In this work, a new water-soluble pillar[5]arene, pillar[4]arene[1]quinone, was designed and synthsized with eight quaternary ammonium groups as well as a quinone units. Such a new water-soluble pillar[4]arene[1]quinone was capable of forming 1:1 stable complex with sodium 1-octanesulfonate in aqueous solution. Since the 1, 4-quinone unit of WP[4]Q[1] could react with ethylenediamine (EDA) to form a conjugated quinoxaline structure, so pillar[4]arene[1]quinone could apply to the facile fluorescence turn-on sensing of EDA in aqueous solution, organic solvent and air.
A mild and efficient photochemical multi-component tandem reaction of quinoxalin-2(1H)-ones, alkenes and sulfinic acids is reported. This tandem reaction could be conveniently carried out at room temperature by employing 4CzIPN as the metal-free photocatalyst and dioxygen (air) as the environmentally benign oxidant. A number of sulfonated quinoxalin-2(1H)-ones were obtained in satisfactory yields with favorable functional group tolerance. Radical trapping experiment and fluorescence quenching experiments were performed to elucidate this visible-light mediated radical reaction process.
Molybdenum disulfide (MoS2) with low cost, high activity and high earth abundance has been found to be a promising catalyst for the hydrogen evolution reaction (HER), but its catalytic activity is considerably limited due to its inert basal planes. Here, through the combination of theory and experiment, we propose that doping Ni in MoS2 as catalyst can make it have excellent catalytic activity in different reaction systems. In the EY/TEOA system, the maximum hydrogen production rate of EY/Ni-Mo-S is 2.72 times higher than that of pure EY, which confirms the strong hydrogen evolution activity of Ni-Mo-S nanosheets as catalysts. In the lactic acid and Na2S/Na2SO3 systems, when Ni-Mo-S is used as co-catalyst to compound with ZnIn2S4 (termed as Ni-Mo-S/ZnIn2S4), the maximum hydrogen evolution rates in the two systems are 5.28 and 2.33 times higher than those of pure ZnIn2S4, respectively. The difference in HER enhancement is because different systems lead to different sources of protons, thus affecting hydrogen evolution activity. Theoretically, we further demonstrate that the Ni-Mo-S nanosheets have a narrower band gap than MoS2, which is conducive to the rapid transfer of charge carriers and thus result in multi-photocatalytic reaction systems with excellent activity. The proposed atomic doping strategy provides a simple and promising approach for the design of photocatalysts with high activity and stability in multi-reaction systems.
Ketones are one of the most important classes of organic compounds, and widely present in various pharmacological compounds, biologically active molecules and functional materials. Over the past few decades, transition metal-catalyzed conversion of aldehydes has been found to be a powerful method. With the continuous development in recent years, it has become an efficient and uncomplicated strategy for constructing ketones. There are four major mechanisms for transition metal-catalyzed ketone synthesis from aldehyde: (1) carbonyl-Heck reaction, that is 1, 2-insertion of organometal species to aldehydic C=O double bond, (2) direct insertion of transition metal catalysts to aldehydic C-H bond, (3) aldehyde as acyl radical, (4) aldehyde as carbon radical acceptor. This article summarizes related reports on the transformations of aldehydes to generate corresponding ketones under different reaction conditions.
Imaging dynamics of membrane proteins of live cells in a wash-free and real-time manner has been a challenging task. Herein, we report unprecedented applications of malachite green (MG), an organic dye widely used in pigment industry, as a switchable fluorophore to monitor membrane enzymes or non-catalytic proteins in live cells. Conformationally flexible MG is non-fluorescent in aqueous solution, yet covalent binding with endogenous proteins of cells significantly enhances its fluorescence at 670 nm by restricting flexibility of dye. Integrating a phosphate-caged quinone methide precursor with MG yielded a covalent labeling fluorogenic probe, allowing real-time imaging of membrane alkaline phosphatase (ALP, a model catalytic protein) activity in live cells with over 100-fold enhancement of fluorescence intensity. Moreover, MG is also applicable to image non-catalytic protein by conjugation with protein-specific ligand. A fluorogenic probe consisted of c-RGDfK peptide and MG proved to be compatible with wash-free and real-time visualization of non-catalytic integrin αvβ3 in live cells with high contrast.
Three novel series of α-aminoamides derivatives were designed and synthesized based on ralfinamide, and their Nav1.7 inhibitory activities were evaluated using manual patch clamp electrophysiology. Active compounds inhibited Nav1.7 with half maximal inhibitory concentration (IC50) values ranging from 2.9 µmol/L to 21.4 µmol/L. Among them, the most potent compound 19h exhibited about 12-fold potency better than ralfinamide. The investigation of their structure-activity relationship gives a strategy to improve the Nav1.7 inhibition of ralfinamide analogues. Compound 19h was efficacious in antinociception in the mouse spared nerve injury (SNI) model of neuropathic pain without causing sedation in the open field test.
Treatment of bone defects still poses a great challenge in orthopedic clinics, and the vital role of periosteum in such processes has attracted widespread attention. However, studies focusing on the oxidative stress micro-environment with an artificial periosteum at the site of defect have been scarce. The intrinsic anti-oxidative properties and therapeutic potential for bone defects of metal-phenolic networks (MPNs) have provided a potential solution to this. Herein, we have developed a protocatechualdehyde + zinc ion (PCA+ZnⅡ) MPN coating on a thermoplastic polyurethane membrane with a one-pot method to fabricate a new-type of periosteum with meritorious biocompatibility and abilities of modulating oxidative stress condition and promoting osteogenesis and mineralization for better bone regeneration, which has shown to be a promising strategy for constructing artificial periosteum with various MPNs.
This study has demonstrated an interesting amplification effect of magnetic field (MF) on the hydroxylamine (HA)-promoted zero valent iron (ZVI)/H2O2 Fenton-like system. Sulfamethoxazole (SMX) could be efficiently degraded at near neutral pH. Conditional parameters affecting the SMX degradation in the ZVI/H2O2/HA/MF system, e.g., pH and the dosages of ZVI, HA and H2O2, were investigated. Unlike the acid-favorable ZVI/H2O2 and ZVI/H2O2/HA systems, the MF-assisted system exhibited good performances even at pH up to 6.0 and highest degradation rate at pH of 5.0. •OH was still identified as the responsible oxidant. A mechanism involving the MF-enhanced heterogeneous-homogeneous iron cycle was proposed in the near-neutral ZVI/H2O2/HA system. Without MF, HA-induced reductive dissolution of the surface iron oxides occurred and thus leaded to homogeneous Fenton reactions. After the introduction of MF, the gradient magnetic field formed on the ZVI particles would induce the generation of concentration cells of Fe(Ⅱ) and local corrosion of iron. Large amounts of aqueous and bounded Fe(Ⅱ) catalyzed H2O2 to efficiently produce •OH, while HA maintained the surface and bulk cycles of Fe(Ⅱ)/Fe(Ⅲ). The result of study is expected to provide a green, energy-free method in improving the effectiveness of ZVI-based Fenton-like technologies at weak-acidic circumstances.
Metal-free heteroatom doped nanocarbons are promising alternatives to the metal-based materials in catalytic ozonation for destruction of aqueous organic contaminants. In this study, N, S co-doped hollow carbon microspheres (NSCs) were synthesized from the polymerization products during persulfate wet air oxidation of benzothiazole. The contents of doped N and S as well as the structural stability were maneuvered by adjusting the subsequent N2-annealing temperature. Compared with the prevailing single-walled carbon nanotubes, the N2-annealed NSCs demonstrated a higher catalytic ozonation activity for benzimidazole degradation. According to the quantitative structure-activity relationship (QSAR) analysis, the synergistic effect between the graphitic N and the thiophene-S which redistributed the charge distribution of the carbon basal plane contributed to the activity enhancement of the N2-annealed NSCs. Additionally, the hollow structure within the microspheres served as the microreactor to boost the mass transfer and reaction kinetics via the nanoconfinement effects. Quenching and electron paramagnetic resonance (EPR) tests revealed that benzimidazole degradation was dominated by the produced singlet oxygen (1O2) species, while hydroxyl radicals (·OH) were also generated and participated. This study puts forward a novel strategy for synthesis of heteroatom-doped nanocarbons and sheds a light on the relationship between the active sites on the doped nanocarbons and the catalytic performance.
Development of new self-calibrating fluorescent sensing methods has been a popular research field with the aim of protecting the human health and environment sustainability. In this work, a novel Eu-based metal organic framework (MOF) Eu(2,6-NDC)(COO) (BUC-88) was developed by employing 2,6-NDC (2,6-naphthalenedicarboxylic acid) as bridging ligands. BUC-88 performed different sensing process toward quinolone antibiotics and tetracyclines antibiotics in terms of fluorescence intensity and color. BUC-88 exhibited excellent selectivity and sensitivity detection property toward enrofloxacin (ENR), norfloxacin (NOR) and ciprofloxacin (CIP) over other Pharmaceutical and Personal Care Products (PPCPs), accomplishing the detection limit of 0.12 μmol/L, 0.52 μmol/L, 0.75 μmol/L, respectively. Notably, BUC-88 acted as an excellent fluorescence sensor for tetracyclines antibiotics with fast response time (less than 1 s), high selectivity and sensitivity (LODs = 0.08 μmol/L). The fluorescent detection method was successfully used for visual and ultrasensitive detection of ENR, NOR, CIP and tetracycline hydrochloride (TC) in lake water with satisfied recovery from 99.75% to 102.30%. Finally, the photoinduced electron transfer and the competitive absorption of ultraviolet light are the main mechanisms for sensitive detection toward quinolone antibiotics and tetracyclines antibiotics.
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