Latest ArticlesDespite the various synthesis approachs to obtain luminous carbon dots (CDs), it is still quite challenging to construct the efficient electrochemiluminescence (ECL) owing to their low ECL reactivity and easy agglomeration. Herein, an efficient and concise ECL system was skillfully constructed by taking advantage of the nitrogen and sulfur co-doped CDs (N, S-CDs) with surfaces rich in hydrazide groups as luminophors to emit intense ECL, and metal-organic framework (MOF) as the matrix to confine CDs in its nanospace. Surprisingly, the proposed CDs assembled MOF (CDs/ZIF-8) enhanced anodic ECL signal up to 250% of pure CDs under the exogenous coreactant-free condition. As a proof of concept, the highly sensitive detection of uric acid (UA) was realized by the constructed ECL platform with a low detection limit of 3.52 nmol/L ranging from 10 nmol/L to 50 µmol/L. This work expanded ideas for the application of pore confinement effect, and provided references for the detection of disease biomarkers of gout and hyperuricemia.
Simple saccharides have a variety of biological functions, but their structural diversity and inherent structural features pose a major challenge for rapid analysis. In this work, we developed a derivative-free and ion mobility-free method for the rapid analysis of monosaccharides and disaccharides using paper spray tandem mass spectrometry. Trimeric cluster ions consisting of saccharide analytes, ligands and transition metal ions are used as precursor ions. We defined the R-value as the ratio of the intensity of the product ion that loses one molecule of ligand over the intensity of the product ion that loses one molecule of saccharide via collision induced dissociation (CID). The species and conformation of simple saccharides can be easily differentiated by calculating this R-value. With the capability of directly analyzing clinical samples using paper spray ionization, our method can be used to rapidly quantify the molar ratio of galactose to glucose in dried plasma samples to aid in the diagnosis of galactosemia. The analytical strategy provided herein has good potential to be applied to a wide range of saccharide analysis applications in the future.
Deuteriodifluoromethyl (CF2D) is a challenging and important functional group due to difficult deuterium incorporation and lack of effective precursor reagents. Herein, we report a bench-stable reagent, deuteriodifluoromethyl phosphine (DDFP) from cheap deuterium source for selectivity deuteriodifluoromethylation of azines with a high deuterium incorporation yield. The late-stage modification of complex molecules further confirmed the potential of this reagent for practical applications. We expect that our reagent to find applications in synthesis of isotope-labelled molecules of interests for drug-discovery and related ilucidation of mechanism of action.
CO oxidation is a vital catalytic reaction for environmental purification, facing challenges due to the catalysts applied to oxidize CO are mainly rare and expensive noble catalysts. Since the high atomic availability, catalytic efficiency, and selectivity of single-atom catalysis, it has been widely studied and proven to be brilliant in CO oxidation. Au single-atom catalysts are regarded as excellent single-atom catalysts in oxidizing CO, whose progress is limited by the indistinct understanding of the reaction mechanism and role of the active atom. Hence, DFT calculation was used to investigate CO oxidation processes, active mechanisms, and the role of Au single-atom. Graphene involving prominent physical and chemical properties was selected as a model supporter. The single-atom support graphene materials exhibit better CO oxidation activities than pristine graphene, among which CO oxidation property on Au/GP is the highest with a 0.38 eV rate-determining barrier following ER mechanism. The outstanding performances including excellent electronic structures, adsorption properties, and strong activation of intermediate products contribute to the high CO oxidation activity of Au/GP, and the Au single-atom is the active center. Our work provides a novel guide for single-atom catalytic CO oxidation, accelerating the development of single-atom catalysis.
MIL-101(Fe)-NH2@Al2O3 (MA) catalysts were successfully synthesized by reactive seeding (RS) method on α-Al2O3 substrate, which demonstrated excellent photo-Fenton degradation performance toward fluoroquinolone antibiotics (i.e., norfloxacin, ciprofloxacin, and enrofloxacin). The structure and morphology of the obtained MA were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), atomic force microscope (AFM). The as-prepared MA could accomplish > 90% of norfloxacin degradation efficiency for 10 cycles' photo-Fenton processes, owing to its excellent chemical and water stability. In addition, the effects of operational factors including H2O2 concentration, foreign ions, and pH on the photo-Fenton degradation of norfloxacin over MA were clarified. The ESR spectra further document that •O2−, 1O2 and •OH radicals are prominent in the decomposition process of antibiotic molecules. Finally, the plausible photo-Fenton norfloxacin degradation mechanisms were proposed and verified.
Herein we report a new general method for one-step synthesis of four kinds of fluoroiodane(Ⅲ) reagents by treating the corresponding aryl iodides with silver difluoride (AgF2). This is the first method applicable for the synthesis of all four fluoroiodane(Ⅲ) reagents including p-iodotoluene difluoride (1), fluoro-benziodoxole (2), fluoro-benziodoxolone (3), and fluoro-N-acetylbenziodazole (4). AgF2 was firstly employed in the direct oxidative fluorination of iodobenzene and thus has shown its outstanding oxidation and fluorine-transfer ability. The use of AgF2 has improved the synthesis of fluoroiodane(Ⅲ) reagents by shortening the reaction steps, avoiding the use of hazardous reagents, and simplifying the experimental operations. It was worth noting that we have developed the first one-step direct synthetic method for 3, while 3 can only be synthesized through Cl→F ligand exchange reaction previously.
Since the discovery of aggregation induced emission (AIE) phenomenon, various stimuli-responsive materials have been rapidly developed, but there are still great challenges in the application of ink printing due to the bad water solubility. In this research, a new cationic amphiphilic TPE-functionalized pyridine salt (TPE-OTs) was designed, which shows good water solubility and hydrochromic properties. The optical properties of the compound have been studied, which is equipped with the typical AIEE characteristics and TICT effect. The compound can self-assemble to form aggregates with a particle size of about 30 nm in water. What is more, the compound is responsive to the environmental humidity, whose fluorescent color changes from green to yellow as the humidity gradually increased. Based on this characteristic, we applied it to the fluorescent anti-counterfeiting ink, realizing the protection and encryption of information.
α, β-Unsaturated primary amides are important intermediates and building blocks in organic synthesis. Herein, we report a ligand-free iron-catalyzed hydroaminocarbonylation of alkynes using NH4HCO3 as the ammonia source, enabling the highly efficient and regioselective synthesis of linear α, β-unsaturated primary amides. Various aromatic and aliphatic alkynes are transformed into the desired linear α, β-unsaturated primary amides in good to excellent yields. Further studies show that using NH4HCO3 as the ammonia source is key to obtain good yields and selectivity. The utility of this route is demonstrated with the synthesis of linear α, β-unsaturated amides including vanilloid receptor-1 antagonist TRPV-1.
Conducting polymer is an important electrode material for supercapacitors because of its high initial specific capacitance. Herein, a novel nanocomposite composed of polypyrrole (PPy) film homogeneously immobilized on the pillar[5]arene functionalized reduced graphene oxide nanosheets (RGO-HP5A-PPy) was successfully prepared. RGO-HP5A induced pyrrole to polymerize on the graphene surface and the specific capacitance loss caused by PPy agglomeration was avoided. Noticeably, the specific capacitance of RGO-HP5A-PPy was up to 495 F/g at 1 A/g. Compared with pure PPy (319 F/g), the specific capacitance was increased by 55%. The specific capacitance retention of the assembled symmetric supercapacitor reached 76% after 10,000 cycles at 5 A/g. This study gave full play to the advantages of pillar[5]arene, graphene and PPy, and was expected to promote the development of supramolecular functionalized composites in energy storage.
The utilization of readily available amino acids, which is not only an oxygen nucleophile but also a nitrogen nucleophile, in palladium-catalyzed allylic substitution is realized under mild conditions. The chemoselectivity and multiple allylation are controlled by adjusting the reaction conditions. This represents the first example of this convenient access to valuable N,O-diallylated amino acids. Under the title conditions, a range of amino acids (α-, β-, γ-) and dipeptides can be readily converted in to the corresponding allylic products with excellent yields (67 examples, up to 99% yield) as well as good functional group tolerance.
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