Electrocatalytic construction of the C–N bond from the derivates of CO2 and N2

Electrochemical synthesis of C-N bond-containing compounds(e.g.,urea,amino acid,amide,amine,and their derivates)from CO₂/N₂and their derivates is emerging as a promising sustainable strategy[1-7].CO₂and its derived products,CO,HCOOH,(COOH)₂,etc.,could serve as carbon sources(Figure 1)[8].N₂,making up 80%of air,is an appealing nitrogen source.However,the low solubility of N2 and the high dissociation energy for the N≡N bond limit its application.     

Transformation of bio-derived acids into fuel-like alkanes via ketonic decarboxylation and hydrodeoxygenation: Design of multifunctional catalyst,kinetic and mechanistic aspects

The combination of a low cost source of Biofine's levulinic acid with available way of valeric acid synthesis opens up new opportunities for valeric acid as a promising bio-derived source for synthesis of valuable compounds for transportation sector. The present review illustrates the development of different approaches to one–pot synthesis of fuel-like alkanes from lignocellulose derived carboxylic acids where particular focus is given to valeric acid consecutive decarboxylative coupling(ketonization) and ketone hydrodeoxygenation in a single reactor over one catalyst bed. The key factors that influence the catalytic performance on both ketonization and hydrodeoxygenation steps as well as their cross-influence will be clarified to provide insights for the design of more efficient catalysts for the one-pot transformation. Valeric acid is considered as a potential acid source from viewpoint of cost effectiveness and feasibility of such transformation with reasonable alkane yield. The both reaction mechanisms and kinetics will also be discussed to understand deeply how the selective C–C coupling and following C=O hydrogenation can be achieved.     

A statistical approach using L<Subscript>25</Subscript> orthogonal array method to study fermentative production of clavulanic acid by <Emphasis Type="Italic">Streptomyces clavuligerus</Emphasis> MTCC 1142

Clavulanic acid is a naturally occurring antibiotic produced by Streptomyces clavuligerus. The present work reports on clavulanic acid production by Streptomyces clavuligerus MTCC 1142 using one-factor-at-a-time and L₂₅ orthogonal array. The one-factor-at-a-time method was adopted to investigate the effect of media components (i.e., carbon source, nitrogen source and inoculum concentration) and environmental factors such as pH for clavulanic acid production. Production of clavulanic acid by Streptomyces clavuligerus was investigated using seven different carbon sources (viz. glucose, sucrose, modified starch, rice-bran oil, soybean oil, palm oil, and glycerol) and six different nitrogen sources (viz. peptone, yeast extract, ammonium chloride, ammonium carbonate, sodium nitrate and potassium nitrate). A maximum yield of 140 μg/mL clavulanic acid was obtained in the medium containing soybean oil as a carbon source and yeast extract as nitrogen source. Subsequently, the concentration of soybean flour, soybean oil, dextrin, yeast extract and K₂HPO₄ were optimized using L₂₅ orthogonal array method. The final optimized medium produced 500 μg/mL clavulanic acid at the end of 96 h as compared to 140 μg/mL before optimization. Synthesis of precursor molecules as a metabolic driving force is of considerable importance in antibiotic synthesis. Attempts to increase the clavulanic acid synthesis by manipulating the anaplerotic flux on C₃ and C₅ precursors by supplementing the medium with arginine, ornithine, proline, valine, leucine, isoleucine, pyruvic acid and á-ketoglutarate were successful. Supplementing the optimized medium with 0.1 M arginine and 0.1 M leucine increased the yield of clavulanic acid further to 1100 μg/mL and 1384 μg/mL respectively.     

An alternative aqueous synthetic route to preparing CdTe quantum dots with tunable photoluminescence

An aqueous synthetic route has been developed for the preparation of mercaptosuccinic acid（MSA）-capped CdTe quantum dots （QDs） using TeO₂ as tellurium source and sodium borohydride as reductant.The size and the emission color of CdTe QDs can be tuned by varying the reflux time.The obtained QDs were characterized by photoluminescence（PL） spectroscopy,X-ray powder diffraction（XRD） and high-resolution transmission electron microscopy（HRTEM）.The results show that the CdTe QDs were of zinc-blende crystal structure in a sphere-like shape.     

Synthesis and Characterization of ZSM-5/β Co-Crystalline Zeolite

ZSM-5/β co-crystalline zeolites with different content of ZSM-5 have been synthesized by adding different amount of ZSM-5 to the synthetic system of β zeolite with NaAlO2, silica sol as the source of aluminum and silica, respectively, and TEA as the template under controlled condition of the synthesis. The ZSM-5/β co-crystalline zeolite was studied by XRD, SEM, BET and NH3-TPD. The reaction activity of toluene alkylation was investigated with a mixture of toluene-methanol as the feedstock in a pulse micro-reactor over the ZSM-5/β co-crystalline zeolite. It is found that ZSM-5/β co-crystalline zeolite has two kinds of zeolite structure including ZSM-5 and β zeolite, not in the form of a physical mixture. The pore structure of ZSM-5/β co-crystalline zeolites is different from that for β zeolite, ZSM-5 and their physical mixture. In addition, the peaks of both high and low temperature desorption of ammonia over the ZSM-5/β co-crystalline zeolite shift 23 ℃ to lower temperatures and the acid amount of its strong acid is 3% more than the physical mixture. So the ZSM-5/β co-crystalline zeolite produces the highest content of xylene, which is 10.4% higher than the physical mixture. And the ZSM-5/β co-crystalline zeolite has better selectivity for toluene alkylation and weaker de-methylation than β zeolite, ZSM-5 and their physical mixture.     

Synthesis of single crystal-like hierarchically mesoporous titanosilicate Ti-SBA-1

Hierarchically mesoporous titanosilicate Ti-SBA-1 was synthesized with organic mesomorphous complexes of polyelectrolyte(poly(acrylic acid)(PAA)) and cationic surfactant(hexadecyl pyridinium chloride(CPC)) as template, tetraethylsiloxane as silica source and titanium ethoxide as titanium source.By adjusting the amount of titanium ethoxide in the synthesis, a series of Ti-SBA-1 particles with different Si/Ti ratio(79–180) were prepared. After incorporation of Ti into the silica framework the wellordered cubic Pm3n mesostructure remained, as well as the morphology, particle size. UV–vis DR spectra of the Ti-SBA-1 materials indicated that incorporated titanium species existed in a highly dispersed state and exhibited tetrahedral and octahedral coordination in the silica framework.     

Ph3P+CF2CO2− as an F− and :CF2 source for trifluoromethylthiolation of alkyl halides

Trifluoromethylthiolation of alkyl halides using Ph₃P⁺CF₂CO₂^- as a fluoride and difluorocarbene source is described. Even though the process involved a cleavage of a C-F bond and the formation of R-S, S C and C-F bonds, the reactions occurred rapidly and were completed within 10 min.     

Flame-retardant Coating by Alternate Assembly of Poly（vinylphosphonic acid） and Polyethylenimine for Ramie Fabrics

A novel intumescent flame retardant coating,consisting of poly(vinylphosphonic acid)(PVPA) as the acid source and branched polyethylenimine(BPEI) as the blowing agent,was constructed on the surface of ramie fabrics by alternate assembly to remarkably improve the flame retardancy of ramie.The PVPA/BPEI coating on the surface of individual fibers of ramie fabric pyrolyzes to form protective char layer upon heating/burning and improves the flame retardancy of ramie.Thermogravimetric analysis reveals that the PVPA/BPEI-coated ramie fabrics left as much as 25.8 wt% residue at 600 °C,while the control(uncoated) fabric left less than 1.4 wt% residue.Vertical flame test shows that all PVPA/BPEI-coated fabrics have shorter after-flame time,and the residues well preserved the original weave structure and fiber morphology,whereas,the uncoated fabric left only ashes.Microscale combustion calorimetry shows that the PVPA/BPEI coatings greatly reduce the total heat release by as much as 66% and the heat release capacity by 76%,relative to those of the uncoated fabric.     

Trimetaphosphate-induced chiral selection between amino acid and nucleoside using 15N-31P coupling NMR

Life on Earth uses a common set of L-amino acids （L-aa） to construct proteins and D-nucleosides （D-Nu） to form nucleic acids,which serve as the carrier of genetic information.Herein,we reveal the intrinsic mechanism of chiral selection of L-aa and D-Nu from the perspective of chemical origin of life.This work employed¹⁵N-labeled L-aa and performed one-pot synthesis of nucleotide amidate of amino acid （N-aa-NMP） using equal amounts of L-¹⁵N-aa and D-¹⁴N-aa with D-...     

Trimetaphosphate-induced chiral selection between amino acid and nucleoside using 15N-31P coupling NMR

Life on Earth uses a common set of L-amino acids （L-aa） to construct proteins and D-nucleosides （D-Nu） to form nucleic acids,which serve as the carrier of genetic information.Herein,we reveal the intrinsic mechanism of chiral selection of L-aa and D-Nu from the perspective of chemical origin of life.This work employed¹⁵N-labeled L-aa and performed one-pot synthesis of nucleotide amidate of amino acid （N-aa-NMP） using equal amounts of L-¹⁵N-aa and D-¹⁴N-aa with D-...     

Application of Microwave Heating Technique to Esterification

Introduction Although the application of microwave technique has been reported as a new type of energy source chemically, it is only in recent years that this technique has been used as the energy source for organic synthesis. In 1986, R. Gedye, et al., published the report of the benzoate synthesis from the respective reactions between benzene carboxylic acid and methanol, propanol or butanol under microwave heating and the catalysis of H_2SO_4.     

High performance liquid chromatography analysis of p-aminophenol synthesized by nitrobenzene transfer hydrogenation using formic acid as hydrogen sourceEI北大核心CSCD

Qualitative analysis of the main by-product of 4-hydroxybenzamide in the synthesis of p-aminophenol bynitrobenzene transfer hydrogenation with formic acid as hydrogen source was carried out by electrospray ionization mass spectrometry. The reaction system was quantitatively analyzed by high performance liquid chromatography. The chromatographic conditions were shown as followsShim pack VP-ODS column250 mm× 4.6 mm5 μµmdetection wavelength of 254 nmVmethanolVbuffer solution=114.8 mmol/L sodium dihydrogen phosphate solution1.9 mmol/L dibasic sodium phosphate solutionas the mobile phase and the flow rate of 0.8 mL/min with a column temperature of 35. Nitrobenzenep-aminophenolaniline and formylaniline in the reaction system were quantitatively analyzed by standard curve method with methyl N-phenylcarbamate as internal standard. The correlation coefficientsR2were 0.99930.99950.9998 and 0.9992 for these analytes respectively. The relative standard deviations RSDs were less than 1.0% 0.3% 0.2% and 0.4% respectively. The recoveries were in the ranges of 95.5%-102.6%101.2%-104.8%95.1%-99.8% and 95.7%-101.1%respectively. This method can be used for the simultaneous determination of main and by-products in the transfer hydrogenation of nitrobenzene with formic acid as hydrogen source. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Nitrogen and boron co-doped graphene nanoribbons as peroxidase-mimicking nanozymes for enhanced biosensing

The rational design of nanozymes with superior activities is essential for improving bioassay performances. Herein, nitrogen and boron co-doped graphene nanoribbons(NB-GNRs) are prepared by a hydrothermal method using urea as the nitrogen source and boric acid as the boron source, respectively.The introduction of co-doped and edge structures provides high defects and active sites. The resultant NB-GNRs nanozymes show superior peroxidase-like activities to nitrogen-doped and boron-doped counterpa...     

Determination of cobalt ion based on polyethyleneimine modified silver nanoclustersEI北大核心CSCD

PolyethyleneiminePEImodified silver nanoclustersAg NCswere synthesized through chemical reduction method by using PEI as stabilizerAgNO3 as silve source and ascorbic acid as reducing agentand it was applied to the detection of cobalt ions. It was found that the fluorescence of the silver nanoclusters was quenched by Co2+ for the aggregation of PEI-Ag NCs caused by the coordination between cobalt ion and amino group on polyethyleneimine. Under the optimized experimental conditionsthe fluorescence quenching degree of PEI-Ag NCs was piecewise linear with the concentration of cobalt ion in the range of 8.30×10-7-4.17×10-4 mol/L and the detection limit was 0.41 μµmol/L. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Antituberculosis and cytotoxic activities of triorganotin(Ⅳ) complexes

Five triorganotin（Ⅳ）（1-5） complexes of cinnamic acid.（Z）-2-acetamido-3-phenylacrylic acid,3-methylbut-2-enoic acid,and 2,2-diphenylacetic acid have been synthesized and characterized by ¹H-¹³C-¹¹⁹Sn NMR,UV,and IR.The spectroscopic investigation demonstrated that the carboxylate group acts as a monodentate ligand in triorganotin（IV） compounds.Five triorganotin（Ⅳ） complexes were screened against the log phase culture of Mycobacterium tuberculosis H37Rv by colorimetric method using XTT dye as growth indicator.The MICs were found to be 0.08 and 1.25μg/mL.     

Fluphenazine hydrochloride radical cation assay:A new,rapid and precise method to determine in vitro total antioxidant capacity of fruit extracts

A new procedure based on generation and subsequent reduction of orange-colored fluphenazine hydrochloride radical(FPH^·+) is presented for the screening of total antioxidant capacity（TAC） of various fruit matrices.The FPH^·+ was obtained by mixing fluphenazine hydrochloride with persulfate（final concentration 2 mmol/L and 0.05 mmol/L,respectively） in 3 mol/L H2SO4 with constant shaking for 5 min.The solution formed showed maximum absorption as 0.8±0.02 at 500 nm in first-order derivative spectrum.The percent inhibition of the solution increased linearly on addition of increasing amounts of standard antioxidants i.e., ascorbic acid etc.The TACs of sample citrus juices were calculated in terms of ascorbic acid equivalents（AAEs） by comparing their inhibition curves with that of ascorbic acid.Comparison of AAE values of different commercial orange juices using the newly developed FPH^·+ assay and the well-known ABTS/K₂S₂O₈ and DMPD/FeCl₃ assays indicated the precision and comparable sensitivity of the method.The proposed procedure is quick,economical,and more precise and gives results comparable to contemporary assays.     

Metal-organic framework as a multi-component sensor for detection of Fe3+, ascorbic acid and acid phosphatase

In this research,a hydroxyl group functionalized metal-organic framework(MOF),UiO-66-(OH)₂,was synthesized as a "on-off-on" fluore scent switching nanoprobe for highly sensitive and selective detection of Fe³⁺,ascorbic acid(AA) and acid phosphatase(ACP).UiO-66-(OH)₂ emits yellow-green light under ultraviolet light,when Fe³⁺ was added,Fe³⁺ was chelated with hydroxyl group,the electrons in the excited state S_1 of the MOF transferred to the half-filled 3 d orbits of Fe³⁺,resulting in fluorescence quenching because of the nonradiative electron/hole recombination annihilation.AA could reduce Fe³⁺ to Fe²⁺,which can destroy the electron transfer between UiO-66-(OH)₂ and Fe³⁺ after AA adding,resulted in nonoccurrence of the nonradiative electron transfer,leading to the recovery of UiO-66-(OH)₂ fluorescence intensity.The probe can also be used to detect ACP based on the enzymolysis of 2-phospho-L-ascorbic acid(AAP) to produce AA.Benefitting from the hydroxyl group and the characteristics of UiO-66,including the high porosity and large surface area,the developed UiO-66-(OH)₂ showed extensive advantages as a fluorescent probe for detection of multi-component,such as high sensitivity and selectivity,colorimetric detection,fast response kinetics and easy to operate,economical and secure.This is the first time to use active group functionalized MOFs as a multicomponent sensor for these three substances detection.     

Decomposition Reaction of Zn-MPA（3-Mercaptopropionic Acid） Complex Under Microwave Irradiation

The thermal decomposition of Zn-MPA complex was investigated under microwave irradiation. ZnO and ZnS nanocrystals could be obtained by decomposing Zn-MPA（3-mercaptopropionic acid） complex under different reaction conditions. It was found that both the pH value of the solution and the molar ratio of Zn2＋ and MPA can play an important role in the formation of ZnO and ZnS nanocrystals. MPA mainly acts as an S source or as a complexing agent. This study provides a new route for the controllable preparation of semiconductor nanocrystals.     

Negative Corona Discharge Ion Source Under Ambient Conditions with Mini Line-cylinder Electrodes

A novel ambient negative corona discharge ion source with mini line-cylinder electrodes is designed. The diameters of inner and outer electrode are 0.16 and 4 mm respectively. With a special assembly method, a perfect coaxiality of the two electrodes is obtained. An injection system utilizing a temperature control technique, achieves a constant and stable concentration of the sample, which is critical to the experiment. The formulas of the corona onset voltage of line-cylinder electrodes are also introduced. The experiment results show that negative substances such as formic acid and acetic acid can be ionized under ambient conditions. When combined with micro electrical mechanical system fabricationprocess, the volume of the ion source can be reduced dramatically, but there is an undesirable surface discharge. To solve the surface discharge problem, an improved structure was designed and tested. The simplicity of the interface of the ion source makes it suitable for mass spectrometer, micro mass spectrometer, ion mobility spectrometer, and high-field asymmetric waveform ion mobility spectrometer applications.     

Promoting CO2 and H2O activation on O-vacancy regulated In-Ti dual-sites for enhanced CH4 photo-production

Engineering the specific active sites of photocatalysts for simultaneously promoting CO₂ and H₂O activation is important to achieve the efficient conversion of CO₂ to hydrocarbon with H₂O as a proton source under sunlight.Herein,we delicately design the In/TiO₂-V_O photocatalyst by engineering In single atoms(SAs) and oxygen vacancies(V_Os) on porous TiO₂.The relation between structure and performance of the ph...