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We present an efficient, fast and simple strategy of generating the intermediate carbamoyl chlorides from secondary amines using stoichiometric amounts of bis(trichloromethyl)carbonate (BTC) in solution and solvent-free conditions with excellent yields. The results obtained showed the yield increasing on whether a base was used. Finally, an efficient and rapid synthesis of variety carbamate derivatives was developed by the reaction with a high variety of different alcohols, phenols, diols and this intermediate at room temperature with grinding and in solvent-free conditions under microwave irradiation. The presence of various safe bases is shown to be effective in reducing the reaction times, increasing the yields and easing purification. The present method does not involve any hazardous phosgene.
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Well-dispersed palladium nanoparticles immobilized onto modified silica (SiO2-pr-NH-cyanuric-SH) have been prepared in some facile steps. The catalyst exhibits high catalytic activity in the Heck reaction, and can be easily recovered and reused without significant loss of its activity in several runs.
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An effective and environmentally benign benzylic oxidation for transition of alkylarenes into the corresponding carbonyl compounds was reported. Alkylarenes were mixed and stirred with potassium bromide, m-chloroperbenzoic acid and a catalytic amount of iodobenzene in water at 60℃ for several hours, a series of the corresponding carbonyl compounds was obtained in moderate to good yields. In the reaction, iodobenzene was first oxidized by m-chloroperbenzoic acid into the hypervalent iodine intermediate which then reacted with potassium bromide to form the key radical initiator for the benzylic oxidation.
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An easy workup and environmentally friendly method to convert ethylbenzene into the corresponding oxides, catalyzed by a combined catalytic system consisting of NHPI and CoSPc, was developed in a water involved liquid-liquid heterogeneous system. Experimental results showed that the reaction performed well facilitated by PTCs at multigrams material level, under which the conversion rate of ethylbenzene and the selectivity of acetophenone reached 60.6% and 95.2% after 0.5 h of reaction in oxygen atmosphere. An oxidation process was proposed at the end of this paper.
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A new synthetic strategy for the synthesis of novel 3-(3-(3-methyl-4-nitroisoxazol-5-yl)-2-phenyl-1-(5,7-diaryl-7H-thiazolo[3,2-a]pyrimidin-3-yl)propyl)-5,7-diaryl-7H-thiazolo[3,2-a] pyrimidines (7a-i) analogues is described. Reaction of 3-(2-(3-methyl-4-nitroisoxazole-5-yl)-1-phenylethyl)pentane-2,4-dione (3) with two moles of thiourea in presence of iodine and CuO afforded 4-(1-(2-aminothiazol-4-yl)-3-(3-methyl-4-nitroisoxazol-5-yl)-2-aryl propyl-thiazol-2-amine (5). Compound 5 on reaction with two moles of chalcone (6) furnished novel 3-(3-(3-methyl-4-nitroisoxazol-5-yl)-2-phenyl-1-(5,7-diaryl-7H-thiazolo[3,2-a]pyrimidin-3-yl)propyl)-5,7-diaryl-7H-thiazolo[3,2-a] pyrimidines (7a-i).
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Selective 3-cyanation of indoles was achieved under heterogeneous catalysis of Ru(III)-exchanged NaY zeolite (RuY) as a recyclable catalyst, in combination with K4[Fe(CN)6] as a nontoxic, slow cyanide releasing agent. Under the aforementioned conditions, good yields of the desired products were obtained.
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A practical six-step synthesis of 12 methylated and hydroxylated isoflavanones was accomplished starting from readily available m-xylene. A significant improvement of this procedure included application of the simple and commercially available reagents, avoidance of expensive reagents and catalysts, simple operations and excellent yields.
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A new series of diaryl urea derivatives bearing N-acylhydrazone moiety were designed and synthesized. All the target compounds were evaluated for their antiproliferative activities against human leukemia cell line (HL-60), human lung adenocarcinoma epithelial cell line (A549) and human breast cancer cell line (MDA-MB-231) in vitro by standard MTT assay. The pharmacological results indicated that some compounds exhibited promising antitumor activities. Compound 1j showed the most potent antiproliferative activity against the tested three cell lines with IC50 values of 0.13 μmol/L, 0.7 μmol/L and 0.5 μmol/L, respectively.
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As the oil crisis and environment concerning deepen, the uses of renewable resources have attracted considerable attention. Polyol intended for synthesis of polyurethane polymers was prepared by a novel direct hydroxylation of soybean oil, alternative to petroleum-based process. The transformation can afford soybean oil polyol in excellent yield with a hydroxyl number up to 467.7 mg KOH/g in the presence of OsO4 as catalyst and NMO as oxidant. The major advantages of this approach are: two hydroxyl groups can be readily added to one double bond, replacing conventional two-step methods by an epoxidation step and then a ring opening step; a wide range of hydroxyl numbers can be obtained via varying catalyst loadings; the reaction can be performed at room temperature. The chemical structure of the polyol prepared was further characterized by chemical methods (hydroxyl number and iodine number) and spectra (1H NMR and FTIR spectroscopy), which con?rmed the cleavage of the double bonds and the produce of hydroxyl groups.
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A series of ω-aminoalkyl ammonium hydrogen phosphates were synthesized though a simple and efficient three-step method. The starting materials, ω-aminoalkyl alcohols (AC-n, with carbon number n=3, 4, 5, 6), were amino-protected with 9-fluorenylmethyl chloroformate (Fmoc-Cl), followed by phosphorylation with POCl3 and deprotection in piperidine/DMF. The structures of each intermediate and final product were confirmed by 1H-NMR, FTIR and mass spectrum. The yield of each step was about 77~92%, with a total yield higher than 56%. This new method was superior in low-cost raw materials, mild reaction temperatures (0~25 °C) and easy purification methods.
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Heterocyclic skeleton building blocks to afford dihydropyrimidinones and dihydropyridines based on neat adducts of diketene, alcohols and aldehydes via silica sulfuric acid (SSA) catalyzed ring opening of diketene in four-component Biginelli-type and Hantzsch-type reactions are presented.
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Fifteen 1-(4-substituted phenyl)-4-(4-bromophenyl)-5-(halo-o-hydroxyphenyl)imino-1,2,3-triazoles were designed and synthesized based on rational combination of 1,2,3-triazoles and (halo) o-hydroxyphenyl group according to the superposition principle of reinforcement of biological activities. All the compounds were tested to an in vitro antimicrobial screening against M.a. and E.c.. Compounds IIe-IIo exhibited more potent antimicrobial activities against M.a. and E.c. than triclosan and fluconazole, which provided valuable information to further study of novel antimicrobial research.
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Li4SiO4ceramic pebble is considered as a candidate tritium breeding material of Chinese Helium Cooled Solid Breeder Test Blanket Module（CH HCSB TBM）for the International Thermonuclear Experimental Reactor (ITER). In this paper, Li4SiO4ceramic pebbles deposited with catalytic metals, including Pt, Pd, Ru and Ir, were prepared by wet impregnation method. The metal particles on Li4SiO4pebble exhibit a good promotion of hydrogen isotope exchange reactions in H2-D2O gas system, with conversion equilibrium temperature reduction of 200−300 ?C. The out-of-pile tritium release experiments were performed using 1.0 wt% Pt/Li4SiO4and Li4SiO4pebbles irradiated in a thermal neutron reactor. The thermal desorption spectroscopy shows that Pt was effective to increase the tritium release rate at lower temperatures, and the ratio of tritium molecule (HT) to tritiated water (HTO) of 1.0 wt% Pt/Li4SiO4was much more than that of Li4SiO4, which released mainly as HTO. Thus, catalytic metals deposited on Li4SiO4pebble may help to accelerate the recovery of bred tritium particularly in low temperature region, and increase the tritium molecule form released from the tritium breeding materials.
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One new isobenzofuranone derivative, 1,4-dimethoxy-3-(3R*-hydroxy-3R*-methyl-1-tetralone)-1(3H)-isobenzofuran (1), was isolated from the broth of marine Streptomyces sp. M268. The structure was elucidated by spectroscopy characteristics as well as comparison with the literature. Compound 1 exhibited cytotoxicities against human cancer cell, HL-60, A549, and BEL-7402.
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Three Eu(III) ternary complexes, Eu(hfa-H)3(Phen), Eu(hfa-H)3(Bipy) and Eu(hfa-H)3(Bath) (hfa=hexafluoroacetylacetonato, Phen=1,10-phenanthroline, Bipy=2,2'-bipyridine, Bath=bathophenanthroline), were synthesized. Their luminescent properties were studied by incorporating deuterated Eu(III) complexes in a poly(methylmethacrylate) (PMMA) matrix, and the results indicated that luminescent PMMA including Eu(hfa-D)3(Bath) showed promising results for applications to novel organic Eu(III) devices, such as the high-power laser materials . Additionally, all the three Eu(III) complexes exhibited good thermostabilization.
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We report the microstructure, application for lithium-ion batteries of mesoporous Co3O4prepared by modified KIT-6 template method. The sample was characterized by XRD, TEM, HRTEM and nitrogen adsorption. Their electrochemical behaviors as electrode reactants for lithium ion batteries were evaluated by cyclic voltammograms and static charge-discharge. A direct comparison of electrochemical behaviors between mesoporous nanostructure and bulk reflects interesting “nanostructure effect”, which is reasonably discussed in terms of how the 3D nanostructures of Co3O4materials function in tuning their electrochemistry. The results demonstrate that further improvement of electrochemical performance in transition metal-oxide-based anode materials can be realized via the design of multiporous nanostructured materials.
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A novel nonenzymatic glucose sensor was successfully fabricated based on the Cu2O polyhedrons covered Cu foil. The Cu2O polyhedrons covered Cu foil was constructed via a facile, low-cost and larger scale producible method. The Cu2O polyhedrons covered Cu foil can be directly used as the working electrode of nonenzymatic glucose sensor, which present good stability and flexibility. The results indicated that the Cu2O polyhedrons modified Cu electrode (Cu2O /Cu electrode) showed high electrocatalytic activity for the oxidation of glucose in alkaline solution. There are two linear regions of glucose concentration for the glucose sensor based on Cu2O /Cu electrode, respectively in 10 μmol/L−0.53 mmol/L (sensitivity: 3029.33 μA (mmol/L)−1 cm−2) and in 0.53 mmol/L to 7.53 mmol/L (sensitivity: 728.67 ?μA(mmol/L)−1 cm−2).
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SrCe0.92Nb0.03Tm0.05O3-δ powders were synthesized by a modified sol-gel method using citrate as a chelating agent. X-ray diffraction (XRD) analysis verified SrCe0.92Nb0.03Tm0.05O3-δ powders and membranes consisting of a single perovskite phase. The morphologies of the sintered membranes were investigated by using scanning electron microscopy (SEM) technique. Stability tests demonstrated that the Nb introduction into doped strontium cerate greatly enhanced the chemical stability. Electrical conductivities of SrCe0.92Nb0.03Tm0.05O3-δ and SrCe0.95Tm0.05O3-δwere measured by the four-point DC method under 10% H2/He atmosphere and temperatures (700-900 °C). With a maximum conductivity of 0.0067 S•cm−1 at 900 °C，the total electrical conductivity ofSrCe0.92Nb0.03Tm0.05O3-δ increases with increasing temperature. The H2 permeation flux of SrCe0.92Nb0.03Tm0.05O3-δ is 0.035 mL•cm−2•min−1 when 40% H2/He and Ar were used respectively as the feed and sweeping gases at 900°C.
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A new and convenient route is developed to synthesize CdSe and core-shell CdSe/CdS quantum dots (QDs) in aqueous solution. The gaseous precursors, H2Se and H2S, generated on-line by reducing SeO32− with NaBH4 and the reaction between Na2S and diluted H2SO4, are used to form high-quality CdSe and CdSe/CdS QDs, respectively. The synthesized water-soluble CdSe and CdSe/CdS QDs possess high quantum yield (3% and 20%) and narrow full-width-at-half-maximum (43 nm and 38 nm). The synthesis process is easily reproducible with simple apparatus and low-toxic chemicals, and can be readily extended to the large-scale aqueous synthesis of QDs.
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Interaction of O2 molecule and a zigzag aluminum nitride nanotube (AlNNT) was studied based on the density functional theory. The O2 molecule is adsorbed on the surface of AlNNT with the adsorption energies in the range of −11.0 to −12.1 kJ/mol. Geometrical structure of the AlNNT remains intact in the presence of oxygen molecule while its electronic structure dramatically changes so that its HOMO (or SOMO)-LUMO gap is approximately reduced to half of its original value. It suggests that the AlNNT may be used as a gas sensor for the O2 detection.
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This paper developed a fluorometric method for the sensitive determination of nonylphenol in water samples by preconcentration with zirconium doped titanium dioxide nanotubes solid phase extraction. The parameters on extraction that would influence the enrichment performance such as the kind and volume of eluent, sample pH, sample flow rate, and sample volume were optimized in detail. Under the optimal conditions, the proposed method provided an excellent linear range of 1−150µg/L and good LOD of 0.076 µg/L. The relative standard deviation (RSDs, n=6) was 2.8 %. Proposed method was also used for the analysis of real water samples and the spiked recoveries were satisfied in the range of 98.7−103%.
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Soluble guanylate cyclase (sGC) is a critical heme-containing enzyme involved in NO signaling. The dimerization of sGC subunits is necessary for its bioactivity and its mechanism is a striking and an indistinct issue. The roles of heme domain cysteines of the sGC on the dimerization and heme binding were investigated herein. The site-directed mutations of three conserved cysteines (C78A, C122A and C174S) were studied systematically and the three mutants were characterized by gel filtration analysis, UV-vis spectroscopy and heme transfer examination. Cys78 was involved in heme binding but not referred to the dimerization, while Cys174 was demonstrated to be involved in the homodimerization. These results provide new insights into the cysteine-related dimerization regulation of sGC.
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Self-assembled monolayers (SAMs) of thiol-derivatized porphyrin molecules on Au substrate has attracted extensively interest for use in sensing, optoelectronic devices and molecular electronics. In this paper, tetra-[p-(3-mercaptopropyloxy)-phenyl]- porphyrin was synthesized and self-assembled with thiol on Au substrate for porphyrin SAMs (PPS4). The electrochemical results demonstrated that PPS4could form excellent SAMs on gold surface. Self-assembled nanojunctions of PPS4were fabricated by using gold nanogap electrodes (gap width: ca. 100 nm). With the light on/off, the nanojunctions showed current high/low as nanometer scaled photo switch
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The electrooxidation of L-cysteine (L-Cys) was studied using a benzoylferrocene (BF) modified multi-wall carbon nanotube paste electrode (BFCNPE) using cyclic voltammetry (CV), square wave voltammetry (SWV) and chronoamperometry (CHA). Under optimum pH in CV the oxidation of L-Cys occurs at a potential about 215 mV less positive than that at the surface of unmodified carbon paste electrode. The catalytic oxidation peak currents were dependent on the L-Cys concentration and a linear calibration curve was obtained in the range 0.7-350.0 μmol/L of L-Cys with SWV method. The detection limit (3σ) was determined as 0.1 μmol/L. This method was also used for the determination of L-Cys in some real samples.
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HTEMPO-functionalized central cores were formed with divinybenzene in “core first” method, and the four or five arms star polymers were built via controlled / living free radical photopolymerization. The four arms star polymers were also prepared with controlled / living free radical photopolymerization in “arm first” method. The resulting polymers had been confirmed by GPC and 1H NMR. It showed that the star polymers had low polydispersities and molecular weight(Mn) with the 85000～560000 g/mol range.
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A new A-B-A type of block copolymers, polyacrylonitrile-block-polydimethylsiloxane-block-polyacrylonitrile (PAN-b-PDMS-b-PAN), which comprises two polymer blocks of different polarities and compatibilities, were synthesized for the first time via reversible addition-fragmentation chain transfer polymerization. Reaction kinetics was investigated. PAN-b-PDMS-b-PAN films were prepared by spin-coating on glass chips. Significant order on the film surface morphologies was observed.
