纳米尺寸材料的结构和性质III：铁纳米粒子的结构和性质

Molecular dynamics computer simulation has been carded out to study the structure and physical properties of iron nanoparticles with 331 to 2133 Fe atoms or with diameter from 2.3 to 4.3 nm. The core of liquid nanodroplets has the similar structure of the bulk molten iron liquid that has an average coordination number around 10.5 and the packing density around 0.45, although the closest Fe-Fe distance is slightly longer in the bulk liquid. Most of the iron nanoparticles formed from the cooling of molten nanodroplets have the same body center cubic crystal structure as it was observed in the bulk under the normal temperature and pressure. Lattice contraction was observed for iron nanoparticles. An amorphous solid and an HCP like solid were obtained accidentally during the quenching runs on Fe331 nanoparticles. The physical properties of iron nanoparticles such as molar volume, density, thermal expansion coefficient, melting point, heat of fusion, heat capacity and diffusion coefficient were estimated based on the results obtained from this simulation. The dependence of physical properties on the nanoparticle sizes was addressed.     

Synthesis and fluorescence properties of CdSe/CdS nanoparticles in aqueous media

On the basis of unique structural characteristics of α-cyclodextrin,α-cyclodextrin modified CdSe/CdS nanoparticles have been successfully synthesized in aqueous media.Techniques of AFM,TEM,EDS,FTIR,UV-vis absorbance and photoluminescence spectra were used to characterize the morphology,composition and optical characteristics of the synthesized nanoparticles.The results showed that the as-synthesized nanoparticles were elliptical and composed of several small particles.Their average length and diameter were ...     

Electrospun Nanofibers Containing p-Nitrophenol Imprinted Nanoparticles for the Hydrolysis of Paraoxon

p-Nitrophenol imprinted nanoparticles with a size range of 150-300 nm in diameter were prepared through miniemulsion polymerization. The imprinted polymer exhibited higher adsorption capacity for p-nitrophenol than the nonimprinted polymer. The hydrolysis of paraoxon in aqueous phase can be accelerated in the presence of the p-nitrophenol imprinted nanoparticles. The hydrolysis rate of paraoxon incorporated with the imprinted nanoparticles was 2.83×10-7 mol/（L·min）, which was about 3.7 times higher compared to the non-imprinted nanoparticles, 12.7 times higher to the spontaneous hydrolysis. The nanoparticles have been mixed with polyacrylonitrile solution and electrospun into nanofibers, which can also be used to accelerate the hydrolysis of paraoxon and conveniently separated from liquid phase for further processing.     

Cooperation between Pt and Ru on RuPt/AC bimetallic catalyst in the hydrogenation of phthalates

RuPt/AC bimetallic catalysts were pre pared by two-step incipient impregnation method and evaluated in the hydrogenation of phthalates.According to the characterization results,well dispersed Ru Pt bimetallic nanoparticles were formed on the catalyst,and the strong interaction between the two metals resulted in the formation of RuPt alloy.It was found that Ru can donate electrons to Pt on RuPt alloy nanoparticles,leading to the formation of electron-deficient Ru which significantly promotes the hydrogenation rate of dioctyl phthalate and improves the selectivity of dioctyl di-2-ethylhexylcyclohexane-1,4-dicarboxylate by accelerating the further hydrogenation of intermediate products.The bimetallic RuPt catalyst also presented excellent stability and versatility in the hydrogenation of phthalates,demonstrating its prospective future in the hydrogenation of aromatic ring contained compounds.     

High Photocatalytic Properties of Zinc OxideNanoparticles with Amidoximated BacterialCellulose Nanofibers as Templates简

The freshly prepared water-wet amidoximated bacterial cellulose （Am-BC） serves as an effective nanoreactor to synthesis zinc oxide nanoparticles by in situ polyol method. The obtained ZnO/Am-BC nanocomposites have been characterized by field emission scanning electron microscopy （FE-SEM）, X-ray diffraction （XRD）, Fourier transformed infrared spectroscopy （FTIR） and thermogravimetric analysis （TGA）. The influence of the zinc acetate concentration on the morphologies and size ofZnO nanoparticles and the possible formation mechanism were discussed. The results indicated that uniform ZnO nanoparticles were homogeneously anchored on the Am-BC nanofibers through strong interaction between the hydroxyl and amino groups of Am-BC and ZnO nanoparticles. The loading content of ZnO nanoparticles is higher using Am-BC as a template than using the unmodified bacterial cellulose. The resultant nanocomposite synthesized at 0.05 wt% shows a high photocatalytic activity （92%） in the degradation of methyl orange.     

表面修饰In纳米微粒的声化学法制备及结构表征

Surface modified indium nanoparticles were prepared by a simple and rapid process from bulk indium via ultrasound dispersion. The morphology and structure of synthesized nanoparticles were characterized by TEM, XRD, XPS and FTIR. The results show that the morphology of indium nanoparticles is spherical and the structure of indium nanoparticles is the tetragonal phase. The surface of indium nanoparticles was coated by 2 ethyl hexanoic acid, which could almost hold back oxidation of the indium nanoparticles. In addition, the tribological property of indium nanoparticles as additives in oil was evaluated on a four-ball tester and the results show that indium nanoparticles exhibit good performance in wear.     

羧基功能化离子液体修饰Pd纳米微粒的制备及结构表征

1-methyl-3-(ω-carboxyl)decyl imidazolium bromine ([C₁₁OOHmim]Br) ionic liquid was synthesized and [C₁₁OOHmim]Br modified Pd nanoparticles were prepared in solution. The morphology and structure of Pd nanoparticles were investigated by IR, TEM, XRD, XPS. The results indicated that the Pd nanoparticles were face-centered cubic structure and the diameter was between 10～30 nm. [C₁₁OOHmim]Br was connected to the surface of Pd nanoparticles by carboxyl and Pd nanoparticles with different sizes could be obtained by varying the amount of the modifier.     

Effects of Ti and Co on the Electrochemical Characteristics of MgNi-Based Alloy Electrodes

Mg-based hydrogen storage alloys MgNi, Mg0.9Ti0.1Ni and Mg0.9Ti0.1Ni0.9Co0.1 were successfully prepared by means of mechanical alloying （MA）. The structure and the electrochemical characteristics of these Mg-based materials were also studied. The results of X-ray diffraction （XRD） and scanning electron microscopy （SEM） show that the main phases of the alloys exhibit amorphous structures, and trace of Ni co-exists. The charge-discharge cycle tests indicate these alloys have good electrochemical active characteristics. And the cycle stability of Ti and Co doped alloy was better than that of MgNi alloy. After 50 cycle charge-discharge, the discharge capacity of the Mg0.9Ti0.1Ni0.9Co0.1 alloy was much better than that of MgNi and Mg0.9Ti0.1Ni alloys. The discharge capacity of Mg0.9Ti0.1Ni0.9Co0.1 was 102.8% higher than that of MgNi alloy, and 45.49% higher than that of the Mg0.9Ti0.1Ni alloy. During the process of charge-discharge cycle test, the main reason for the electrode capacity fading is the corrosion of Mg to Mg（OH）2 on the surface of alloys. The Tafel polarization test indicates Ti and Co improve the anticorrosion in an alkaline solution. The EIS results suggest that proper amount of Ti and Co doping improve the electrochemical catalytical activity on the Mg-based alloy surface significantly.     

Preparation, characterization and adhesive properties of di- and tri-hydroxy benzoyl chitosan nanoparticles

Modified chitosans with 3,4-di-hydroxy benzoyl groups (CS-DHBA) and 3,4,5-tri-hydroxy benzoyl groups (CS-THBA) were synthesized and their nanoparticles were prepared via ionic crosslinking by tripolyphosphate (TPP). The chemical structure and degree of substitution (DS) of di-and tri-hydroxy benzoyl chitosans are determined by FTIR and 1H-NMR spectroscopy. The morphology of particles, size distribution and zeta potential of nanoparticles were studied using transmission electron microscopy (TEM) and dynamic light scattering (DLS), respectively. The mean diameters of particles of CS-DHBA and CS-THBA nanoparticles were 144 nm and 112 nm, respectively. It was found that the particles size decreased slightly with decreasing the degree of substitution and increasing degree of deacetylation (DD), due to increasing of ionic crosslinking of ammonium ions and polyanions of tripolyphosphate. The TEM photographs of CS-DHBA show that these particles are spherical in shape, but the particles of CS-THBA show some aggregation. In addition, the solubility and the mechanical properties of the prepared modified chitosans and their nanoparticles were evaluated for bio-adhesive and biomedical application. The results of solubility tests indicated that, the CS-DHBA and CS-THBA have higher solubility at pH > 7 comparing to CS. Also the CS-DHBA, CS-THBA and their nanoparticles showed a significant adhesive capacity and enhanced tensile strength and tensile modulus.     

Synthesis and Luminescent Property of Polycarbazole/Polyhedral Oligomeric Silsesquioxane Nanocomposites

Polyvinylcarbazole（PVK） composites containing organic-inorganic hybrid polyhedral oligomeric silse-squioxane（POSS） PVK-POSS were prepared by free radical polymerization. POSS monomers reacted with vinylcarbazole and were completely dispersed at molecular level in PVK matrix and PVK-POSS nanocomposites display higher glass transition temperature（Tg） in comparison with neat PVK. Optical properties of PVK/POSS nanocomposites were investigated by UV-spectrum and PL-spectrum and the results show that the PVK-POSS nanoparticles have a good interface effect and improve color purity effectively. The maximum absorption wavelength bathochromically shifts gradually with the increasing of the content of POSS. The luminescent intensity becomes higher and higher with the increase of POSS content, and reaches its maximum luminescent intensity when the POSS content is 3% （mass fraction）, while some POSS-rich nanoparticles are present in matrix when contents of POSS are beyond 5%.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.