Encapsulating polysulfide with high pyridinic nitrogen-doped ordered mesoporous carbons for long-life lithium-sulfur batteries

Rechargeable lithium-sulfur(Li-S)batteries are promising candidates for next-generation batteries because of their high theoretical specific capacity(1675 mAh/g)and specific energy(2600 Wh/kg);more-over,S is abundant,inexpensive,non-toxic,and environment friendly.However,the inherent insulating nature of S,discharge products of Li 2S,and dissolution of Li polysulfides(LiPSs)severely limit the practical applications of Li-S batteries.In this study,an N-doped ordered mesoporous carbon(NOMC)with a large specific surface area and high pyridinic N content was successfully prepared via the hard templating method.The synergetic effects of physical nanoconfinement and chemisorption restricted the LiPSs dissolution in the electrolyte.Graphitic N improved the electrical conductivity of the C materials,and pyridinic N effectively adsorbed the LiPSs,thereby inhibiting the shuttling of polysulfides in the electrolyte.The obtained C material was used as an S host,and the resultant S@NOMC composite exhibited a first discharge capacity of 853 mAh/g.The capacity of the composite was retained at 679 mAh/g after 500 cycles at 1 C,which corresponds to a decay rate of 0.042%per cycle.

Fabricating pyridinic N-B sites in porous carbon as efficient metal-free electrocatalyst in conversion CO_(2)into CH_(4)

Electrochemical reduction of CO_(2)(CO_(2)RR)to value-added chemicals is an attractive strategy for greenhouse gas mitigation and carbon recycle.Carbon material is one of most promising electrocatalysts but its product selectivity is limited by few modulating approaches for active sites.Herein,the predominant pyridinic N-B sites(accounting for 80%to all N species)are fabricated in hierarchically porous structure of graphene nanoribbons/amorphous carbon.The graphene nanoribbons and porous structure can accelerate electron and ion/gas transport during CO_(2)RR,respectively.This carbon electrocatalyst exhibits excellent selectivity toward CO_(2)reduction to CH_(4)with the faradaic efficiency of 68%at−0.50 V vs.RHE.As demonstrated by density functional theory,a proper adsorbed energy of∗CO and∗CH_(2)O are generated on the pyridinic N-B site resulting into high CH_(4)selectivity.Therefore,this study provides a novel method to modulate active sites of carbon-based electrocatalyst to obtain high CH_(4)selectivity.

Enhanced stability of nitrogen-doped carbon-supported palladium catalyst for oxidative carbonylation of phenol

Enhancing the stability of supported noble metal catalysts emerges is a major challenge in both science and industry.Herein,a heterogeneous Pd catalyst(Pd/NCF)was prepared by supporting Pd ultrafine metal nanoparticles(NPs)on nitrogen-doped carbon;synthesized by using F127 as a stabilizer,as well as chitosan as a carbon and nitrogen source.The Pd/NCF catalyst was efficient and recyclable for oxidative carbonylation of phenol to diphenyl carbonate,exhibiting higher stability than Pd/NC prepared without F127 addition.The hydrogen bond between chitosan(CTS)and F127 was enhanced by F127,which anchored the N in the free amino group,increasing the N content of the carbon material and ensuring that the support could provide sufficient N sites for the deposition of Pd NPs.This process helped to improve metal dispersion.The increased metal-support interaction,which limits the leaching and coarsening of Pd NPs,improves the stability of the Pd/NCF catalyst.Furthermore,density functional theory calculations indicated that pyridine N stabilized the Pd^(2+)species,significantly inhibiting the loss of Pd^(2+)in Pd/NCF during the reaction process.This work provides a promising avenue towards enhancing the stability of nitrogen-doped carbon-supported metal catalysts.

Boosting Fischer-Tropsch Synthesis via Tuning of N Dopants in TiO_(2)@CN-Supported Ru Catalysts

Nitrogen(N)-doped carbon materials as metal catalyst supports have attracted signifi cant attention,but the eff ect of N dopants on catalytic performance remains unclear,especially for complex reaction processes such as Fischer-Tropsch synthesis(FTS).Herein,we engineered ruthenium(Ru)FTS catalysts supported on N-doped carbon overlayers on TiO_(2)nanoparticles.By regulating the carbonization temperatures,we successfully controlled the types and contents of N dopants to identify their impacts on metal-support interactions(MSI).Our fi ndings revealed that N dopants establish a favorable surface environment for electron transfer from the support to the Ru species.Moreover,pyridinic N demonstrates the highest electron-donating ability,followed by pyrrolic N and graphitic N.In addition to realizing excellent catalytic stability,strengthening the interaction between Ru sites and N dopants increases the Ru^(0)/Ru^(δ+)ratios to enlarge the active site numbers and surface electron density of Ru species to enhance the strength of adsorbed CO.Consequently,it improves the catalyst’s overall performance,encompassing intrinsic and apparent activities,as well as its ability for carbon chain growth.Accordingly,the as-synthesized Ru/TiO_(2)@CN-700 catalyst with abundant pyridine N dopants exhibits a superhigh C_(5+)time yield of 219.4 mol CO/(mol Ru·h)and C_(5+)selectivity of 85.5%.

Synthesis and Characterization of Novel Schiff Base for Enhanced Dye-Sensitized Solar Cell Photo-Response Mechanism

The efficient photo-response mechanism is one of the key factors in the commercialization of dye-sensitized solar cells in a bid to satisfy renewable energy demands. Progress in green technology has put solar energy on the front burner as a provider of clean and affordable energy for a sustainable society. We report the synthesis of a novel Schiff base with optical transparency in the visible and near IR region of the solar spectrum that can find application in the DSSCs photo-response mechanism. The synthesized crystal exhibited features that could handle some of the shortcomings of dye-sensitized solar cells which include wide band solar spectrum absorption and capability for swift charge transfer within the photoelectrodes. The synthesized Schiff base was characterized using x-ray diffractometer, UV/Visible spectrometer, Frontier transmission infrared spectrometer and conductometer. XRD data revealed the grown crystal to have an average crystallite size of 2.08 nm with average microstrain value of about 269.43. The FT-IR recorded transmission wave ѵ (CO) at 1207.7 cm−1 while dominant wave occurred at ѵ1654.9 and ѵ1592.3 cm−1 relating to ѵ (CN) stretching and ѵ (NH) bending respectively were observed. The IR spectrum revealed the bonding species and a probable molecular structure of 2,6-bis(benzyloxy)pyridine. The UV/Visible spectra convoluted to maximum peak within the near IR region suggesting that 2,6-bis(benzyloxy)pyridine can absorb both the visible and near IR region while its electrical conductivity was determined to be 4.58 µS/cm. The obtained result of the present study revealed promising characteristics of a photosensitizer that can find application in the photo-response mechanism of DSSCs.

New Neuraminidase Inhibitory Alkaloids from the Mangrove Soil-Derived Fungus Arthrinium sp.SCSIO 41305

New alkaloid,(E)-2-(hydroxyimino)-4-methylpentanamide(1)and a new cyclopentano[b]pyridine,4-hydroxy-7-methyl-6,7-dihydro-5H-cyclopenta[c]pyridin-5-one(2),together with ten known compounds(3–12)were isolated from the mangrove soil-derived fungus Arthrinium sp.SCSIO 41305.Extensive spectroscopic analysis and X-Ray crystallographic analysis were used to elucidate the structure of(E)-2-(hydroxyimino)-4-methylpentanamide(1),including its absolute configuration.All the isolated compounds(1–12)were evaluated for their antimicrobial and enzyme inhibitory activities against acetylcholinesterase(ACh E),neuraminidase(NAs),and phosphatidylinositol 3-kinase(PI3K).Among them,compounds 1 and 3 exhibited strong neuraminidase inhibitory activity with IC_(50)values of 12.04,1.92μmol L^(-1)(IC_(50)20μmol L^(-1)for oseltamivir acid),while compounds 5,6,8,and 10showed moderate neuraminidase inhibitory activity,and compounds 6–10 displayed weak enzyme inhibitory activities against PI3K.

Encapsulation of Ru(II) Polypyridine Complexes for Tumor-Targeted Anticancer Therapy

Ru(II)polypyridine complexes have attracted much attention as anticancer agents because of their unique photophysical,photochemical,and biological properties.Despite their promising therapeutic profile,the vast majority of compounds are associated with poor water solubility and poor cancer selectivity.Among the different strategies employed to overcome these pharmacological limitations,many research efforts have been devoted to the physical or covalent encapsulation of the Ru(II)polypyridine complexes into nanoparticles.This article highlights recent developments in the design,preparation,and physicochemical properties of Ru(II)polypyridine complex-loaded nanoparticles for their potential application in anticancer therapy.

以NBS/Pyridine氧化体系合成芳基芳酰基偶氮化合物

以芳基芳酰肼类化合物为原料,NBS/Pyridine为氧化体系,在室温下将芳基芳酰肼类化合物氧化脱氢得芳基芳酰基偶氮化合物,收率80%～92%。产品的结构经元素分析、IR、1HNMR确证。

三棱的化学成分研究

目的:研究三棱Sparganium stoloniferumBuch.-Ham.的化学成分。方法:采用硅胶柱层析,Sephadex LH-20,ODS C-18,重结晶等方法,根据理化性质和光谱鉴定化合物的结构。结果:从三棱中得到8个化合物,分别为棕榈酸(1),5-羟甲基糠醛(2),6,7,10-三羟基-8-十八烯酸(3),棕榈酸单甘油酯(4),5-Hydroxy-2-(hydroxymethyl)pyridine(5),β-谷甾醇(β-sitosterol)(6),β-胡萝卜苷(daucosterol)(7),Betulinic acid(8)。结论:化合物5,8为首次从该植物中分离得到。

Designing g-C_(3)N_(4)/N-Rich Carbon Fiber Composites for High-Performance Potassium-Ion Hybrid Capacitors

Potassium-based energy storage devices(PEDS)are considered as hopeful candidates for energy storage applications because of the abundant potassium resources in nature and high mobility in the electrolyte.although carbon materials show great potential for potassium-ion storage,poor rate performance,and unsatisfactory cycle lifespan in existing carbon-based PIBs anode,it also cannot match the dynamics and stability of the capacitor cathode.Nitrogen doping has been proven to be a effective modification strategy to improve the electrochemical performance of carbon materials.Hence,we prepare carbon nanofibers and g-C_(3)N_(4)composites with high nitrogen contents(19.78 at%);moreover,the sum of pyrrolic N and pyridinic N is up to 59.51%.It achieves high discharge capacity(391 m Ah g^(-1)at0.05 A g^(-1)),rate capacity(141 m Ah g^(-1)at 2 A g^(-1)),and long cycling performance(201 m Ah g^(-1)at 1 A g^(-1)over 3000 cycles)when as an anode for PIBs.Furthermore,it can deliver promising discharge capacity of132 m Ah g^(-1)at 0℃.Moreover,as battery anode for potassium-ion hybrid capacitors(PIHC)device with an active carbon cathode,it delivers energy/power density(62 and 2102 W kg^(-1))as well as high reversible capacity(106 m Ah g^(-1)at 1 A g^(-1)).

Synthesis,Crystal Structure and Antifungal Activity of 4-(5-((2,4-Dichlorobenzyl)thio)-4-phenyl-4H-1,2,4-triazol-3-yl)pyridine

The title compound 4-（5-（（2,4-dichlorobenzyl）thio）-4-phenyl-4H-1,2,4-triazol-3- yl）pyridine （C20HI4CI2N4S） was synthesized, and its structure was confirmed by 1H NMR, MS, elemental analyses and X-ray diffraction. It crystallizes in the monoclinic system, space group P21/c with a = 14.885（5）, b = 8.597（2）, c = 16.144（5）A,β= 114.505（4）°, V= 1879.8（10） A3, Z= 8 and R = 0.0320 for 3108 observed reflections with I 〉 2σ（I）. The preliminary biological test shows that the title compound has activities against Stemphylium lyeopersici （Enjoji） Yamamoto, Fusarium oxysporum, sp. cueumebrium, and Botrytis cinerea with inhibitory to be 53.57%, 66.67% and 24.44%, respectively.

Synthesis of 2, 6-(substituded)pyridine Derivatives Using Amide and Imine Groups

A new wo-armed?acyclic diamide Ia 2, 6-bis(1-ethanecarbozamido-2-amino)pyridine, and a new series of aromatic aldehyde schiff bases containing pyridine ring and amide bridge, IIa-f, were prepared. The compounds were characterized by elemental analysis, IR, 1HNMR and MS. The bioactivity half inhibitory concentration C1/2 is given.

Microwave Assistant Synthesis and Dimeric Crystal Structure of 2-(((6-Chloropyridin-3-yl)-methyl)thio)-5-(pyridin-4-yl)-1,3,4-thiadiazole

The title compound 2-(((6-chloropyridin-3-yl)methyl)thio)-5-(pyridin-4-yl)-1,3,4-thiadiazole 5(C26H18Cl2N8S4) was synthesized, and its structure was confirmed by 1H NMR, MS and elemental analyses and X-ray diffraction. It crystallizes in the triclinic system, space group P1 with a = 9.452(4), b = 12.335(4), c = 13.017(5) A, α = 90.624(5), β = 110.541(5), γ =104.879(4)°, Dc = 1.561 g/cm3, Z = 2, V = 1364.9(9) A3, F(000) = 656, the final R = 0.0300 and w R = 0.0635 for 4206 observed reflections with I 】 2σ(I). The preliminary biological test showed that the title compound has activities against Stemphylium lycopersici(Enjoji) Yamamoto, Fusarium oxysporum. sp. cucumebrium, and Botrytis cinerea with inhibitory activities to be 9.82%, 44.44% and 20.00%, respectively.

Kinetic hydrate inhibitor performance of new copolymer poly(N-vinyl-2-pyrrolidone-co-2-vinyl pyridine)s with TBAB

In oil and gas field, the application of kinetic hydrate inhibitors （KHIs） independently has remained problematic in high subcooling and high water-cut situation. One feasible method to resolve this problem is the combined use of KHIs and some synergists, which would enhance KHIs’ inhibitory effect on both hydrate nucleation and hydrate crystal growth. In this study, a novel kind of KHI copolymer poly（N-vinyl-2-pyrrolidone-co-2-vinyl pyridine）s （HGs） is used in conjunction with TBAB to show its high performance on hydrate inhibition. The performance of HGs with different monomer ratios in structure II tetrahydrofuran （THF） hydrate is investigated using kinetic hydrate inhibitor evaluation apparatus by step-cooling method and isothermal cooling method. With the combined gas hydrate inhibitor at the concentration of 1.0 wt%, the induction time of 19 wt% THF solution could be prolonged to 8.5 h at a high subcooling of 6℃. Finally, the mechanism of HGs inhibiting the formation of gas hydrate is proposed.

Synthesis of a new pyridine-containing diamine and related polyimide

A new kind of aromatic diamine monomer containing pyridine unit,2,6-bis[4-(4-aminophenoxy)phenoxy]pyridine(BAPP),was synthesized in three steps,using hydroquinone as starting material.A novel pyridine-containing polyimide was prepared from the resulting diamine BAPP with 4,4 -oxydiphthalic anhydride(ODPA) via a conventional two-step thermal imidization method.The resulting polyimide exhibits excellent solubility,film-forming capability and high thermal resistance.

HALOMETHYLATION OF POLYSTYRENE AND SUBSEQUENT PYRIDINATION VIA A HOMOLYTIC PATHWAY

Chloromethylation of polystyrene （PS） with two different chloromethylating systems methylal/thionyl chloride and paraformaldehyde/trimethylchlorosilane was studied. Soluble chloromethylated polystyrene with a degree of substitution of 89% was obtained. The Conant-Finkelstein reaction on the chloromethylated PS afforded soluble iodomethylated polystyrene with a degree of substitution as high as 96%. The reaction conditions of Minisci were employed to radically pyridinate PS via its iodomethylated derivative. Polyelectrolytes were formed which could be converted to normal polymers by treatment with a 20% aqueous solution of NaOH.

Synthesis,Crystal Structure,DFT Studies and Biological Activity of a Novel Schiff Base Containing Triazolo[4,3-a]pyridine Moiety

The novel Schiff base（E）-8-chloro-NA-（4-（dimethylamino）benzylidene）-[1,2,4]triazolo[4,3-a]pyridine-3-carbohydrazide was synthesized and characterized by ^1H NMR,MS,elemental analysis and X-ray diffraction.The compound crystallizes in the monoclinic space group P2_1/c with a = 7.091（2）,b = 10.750（3）,c = 21.380（6） A,β = 96.299（6）°,V = 1619.7（8） A^3,Z = 4 and R = 0.0351.Theoretical calculation of the title compound was carried out with the B3LYP/6-31 G basis set.The frontier orbital energy and atomic net charges were discussed.It is found that the experimental data show good agreement with the calculated values.And the compound exhibits good antifungal activity against Stemphylium lycopersici（Enjoji） Yamamoto.

Synthesis and characterization of novel star-shaped pyridine cored compounds with alternating carbazole and triphenylamine moieties

Amorphous 2,4,6-trissubstituted pyridines containing three peripheral carbazole or two triphenylamine and one carbazole moieties, respectively, have been synthesized and characterized. The properties of the compounds are investigated by UV-vis absorption, photoluminescence spectroscopy, thermal analysis as well as cyclic voltammetry. The results show that the compounds have high thermal stability, emit blue light. Also, the compounds possess the HOMO and LUMO energy levels comparable to those of NPB. The effects of different substituents on the electronic properties of the materials have been discussed.

Studies on the Synthesis of Pyridine Analogs of the Natural Product3,5,4'-Trimethoxystilbene

Five pyridine analogs of the natural product, 3, 5, 4'-trimethoxystilbene, were synthesized. The final compounds were characterized by 1H-NMR.