The transformations of fluoroalkyl-containing 2-arylhydrazono-1,3-dicarbonyl compounds with methylamine

Fluoroalkylated 1,2,3-triketone 2-arylhydrazones and 2-arylhydrazono-3-oxo esters react variously with methylamine depending on the structure of the fluorinated substituent. 2-Arylhydrazono-1,3-dicarbonyl compounds having “short” fluoroalkyl substituents condense with methylamine at the carbonyl group attached to the non-fluorinated substituent whereas ones containing a lengthy polyfluoroalkyl substituent undergo haloformic cleavage as a result of the amine addition at the carbonyl group bearing such a substituent. The resulting 2-arylazo-3-(N-methyl)amino-1-polyfluoroket-2-en-1-ones and 1-(N-methyl)amino-2-arylhydrazono-3-fluoroalkyl-3-oxopropanamides have complexing properties, and they can bind to nickel(II) and copper(II) ions. Nickel chelates can be obtained by a three-component condensation of 2-arylhydrazono-1,3-dicarbonyl compounds and methylamine in the presence of nickel(II) cations.     

Nucleophilic substitution with amines: dihydro-1,2,4,5-tetrazines are more useful precursors than 1,2,4,5-tetrazines

A one step synthesis of (di)alkylamino-substituted 1,2,4,5-tetrazines direct from 3,6-disubstituted-1,2-dihydro-1,2,4,5-tetrazine precursors is described. A comparative study revealed that the described method not only avoids the up-to-now required oxidation step but also lower reaction times and/or temperatures compared to usual protocols. The efficiency of the reaction was highlighted by a practical synthesis of 3,6-bis(methylamino)-1,2,4,5-tetrazine using aqueous methylamine. Other primary and secondary amines were also found to give disubstitution products when reacted with 3,6-bis(methylsulfanyl)-1,2,4,5-dihydrotetrazine.     

The Use of Chronoamperometry and Chemometrics for Optimization of Conducting Polymer Sensor Arrays

A general approach using principal component analysis was applied to amperometric data obtained from flow injection analysis (FIA) to select conducting electroactive polymers (CEPs) and applied potential waveforms for discrimination of potassium and methylamine. The results were compared with the selection from the application of the PCA approach for cyclic voltammetry data in our previous research. Good agreement between the two methods of selection was found, which indicates that within the general qualitative limits of the approach, PCA can be applied for selection of chemical and electrochemical parameters for FIA detection/discrimination using CEP sensor arrays detector for a range of analytes.     

Methylamine interaction with proteins of photosystem II: A comparison with biogenic polyamines

Biogenic polyamines are essential for cell growth and differentiation. The interaction of polyamines with protein of photosystem II (PSII) are well investigated, while there has been no report on the effect of monoamines complexation on photosynthetic oxygen evolution. This study was designed to investigate the interaction of methylamine with proteins of PSII, using PSII-enriched submembrane fractions with various concentrations of methylamine. Fourier transformed infrared (FTIR) and fluorescence spectroscopic methods were used in order to determine the methylamine binding mode, the protein conformational changes, and the effect of amine interaction on photosynthetic oxygen evolution. Spectroscopic evidence showed that methylamine interacts with protein (H-bonding) through polypeptide CO, C–N and NH groups with major perturbations of protein secondary structure. Major reduction of α-helix from 50% (free PSII) to 35% with an increase of β-sheet from 10% (free PSII) to 16% was observed in methylamine-PSII complexes. At very low methylamine concentration, no inhibition of oxygen-evolution occurred, while at higher amine content (12 mM), 100% inhibition was observed. Chlorophyll (Chl) fluorescence measurements indicated the inhibition mainly affects the oxygen evolving complex (OEC) of PSII. Comparisons of the effects of methylamine with biogenic polyamine spermine, spermidine and putrescine showed a similar mode of binding with protein (H-bonding) through polypeptide CO, C–N and NH groups. However, major alterations of the protein secondary structure are induced by monoamine and not by polyamines.     

Syntheses,structural determination,and binding studies of nine-coordinate multinuclear (mnH)2[EuIII(egta)]2·6H2O and binuclear (mnH)4[EuIII2(dtpa)2]·6H2O

Two lanthanide complexes, (mnH)₂[Eu^III(egta)]₂·6H₂O (1) (H₄egta = ethyleneglycol-bis-(2aminoethylether)-N,N,N′,N′-tetraacetic acid) and (mnH)₄[Eu^III₂(dtpa)₂]·6H₂O (2) (H₅dtpa = diethylenetriamine-N,N,N′,N″,N″-pentaacetic acid), have been synthesized and characterized by FT-IR spectroscopy, thermal analysis, and single-crystal X-ray diffraction. X-ray diffraction reveals that 1 is multinuclear nine-coordinate and crystallizes in the monoclinic crystal system with space group C2/c. The obtained cell dimensions are a = 38.513(3)?Å, b = 13.5877(8)?Å, c = 8.7051(5)?Å, β = 99.6780(10)°, and 4490.6(5)?ų. Each methylamine (mnH⁺) cation in 1, through hydrogen bonds, connects three adjacent [Eu^III(egta)]^? anions. The [Eu^III(egta)]^? anions connect one another forming a 1-D multinuclear zigzag chain structure along the c-axis. Complex 2 is nine-coordinate binuclear structure with tricapped trigonal prismatic conformation and crystallizing in the monoclinic crystal system, but with space group P2₁/n. The obtained cell dimensions are a = 9.9132(8)?Å, b = 24.1027(18)?Å, c = 10.7120(10)?Å, β = 109.1220(10)°, and 2418.2(3)?ų. For 2, there are two kinds of methylamine cations (mnH⁺) connecting [Eu^III₂(dtpa)₂]^4? complex anions and lattice waters through hydrogen bonds, leading to formation of a 2-D ladder-like layer structure.     

高硅FAU沸石与甲胺吸附物的相互作用

合成高硅沸石中所用的模板剂胺类分子与沸石骨架 Si—O基团间的相互作用机理尚不清楚 .迄今为止 ,沸石与吸附胺之间的相互作用的研究还只限于测定沸石酸性质 [1,2 ]、表面羟基活性位或了解模板分子在沸石骨架中的位置和状态 [3,4 ] .甲胺、乙胺在骨架完美的高硅 FAU(Y型 )沸石上的亲和性指数 AT 值 ,即被吸附有机物脱附峰温与该有机物的沸点之差分别高达 1 60与 1 5 0℃[5] .而在高硅 MFI(Silicalite-1 )沸石上为 1 60与 1 2 7℃ [6 ] .与大多数有机物不同 ,被吸附的胺类脱附时的吸热效应十分明显 .上述现象表明胺与高硅沸石骨架 O2 -…     

甲胺分子多光子电离质谱研究

胜多光子电离飞行时间质谱法，利用可调谐脉冲激光器，测得了甲胺分子在不同激光波长和激光功率下的多光子电离和解离产物。母体离子ＣＨ３ＮＨ＾＋２的离解速常数随激光发波长的增大而减小。     

M/Al2O3-CeO2（M=Pt-Ru，Ru，Pt）催化剂在甲胺催化湿式氧化中的活性与选择性

采用浸渍法制备了M/Al₂O₃-CeO₂（M=Pt-Ru,Ru,Pt）催化剂,并将其用于甲胺的催化湿式氧化反应（CWAO）.结果表明,Pt-Ru/Al₂O₃-CeO₂具有最佳活性和选择性.运用程序升温还原、X射线光电子能谱、X射线衍射、透射电子显微镜、N₂吸附和CO化学吸附等技术对催化剂的物化性质进行了表征.Pt组分的引入可有效提高双金属催化剂活性组分的分散度,从而明显提高了其催化性能.升降温过程中总有机碳（TOC）转化率与N₂选择性迟滞效应表明,甲胺CWAO遵循化学吸附-脱附机理.     

反相液相色谱-质谱法使用甲酸甲胺改善甘油三酯电喷雾离子化检测灵敏度

提出使用甲酸甲胺作为新型电离增强剂改善反相液相色谱-电喷雾质谱(LC-ESI-MS)检测甘油三酯灵敏度的方法.使用反相C18色谱柱,以玉米油的异丙醇溶液为样品,选择文献中常用的异丙醇-乙腈-甲醇-水,异丙醇-乙腈流动相,在考察甲酸、乙酸、甲酸铵、乙酸铵、甲酸丁胺、甲酸二丁胺、甲酸三乙胺、甲酸二乙胺、甲酸甲胺、甲酸乙胺等不同电离增强剂的基础上,比较了甲酸甲胺和常用的甲酸铵电离增强剂对LC-ESI-MS分析甘油三酯检测灵敏度的影响,结果表明,甲酸甲胺可以使其中三亚油酸甘油酯组分的质谱峰响应值和信噪比均约为使用甲酸铵的5倍.考察了使用甲酸甲胺时,甲酸甲胺电离增强剂的浓度、流动相流速以及雾化气流速对检测的影响.通过测定不同玉米油浓度与其中甘油三酯总离子流色谱峰面积的关系曲线,显示玉米油中甘油三酯组分在不同流动相的电喷雾过程中出现聚集的最小浓度相差不大,三亚油酸甘油酯峰面积与浓度在7×10-7~2×10-4 mol/L范围内的线性关系较好,相关系数R2=0.9997,在更高的浓度时则峰面积增加缓慢.根据实验数据分析甲酸甲胺改进检测的机理,提出含有疏水性基团的加合甲胺单电荷离子具有较低的溶剂化能,在雾滴表面富集的加合甲胺离子容易被蒸发,从而提高了电喷雾离子化效率.本方法为LC-ESI-MS分析食用油中甘油三酯时提高检测灵敏度提供了有效途径.     

Ruthenium deposited on MCM-41 as efficient catalyst for hydrolytic dehydrogenation of ammonia borane and methylamine borane

Ultrafine Ru nanoparticles are successfully deposited on MCM-41 by using a simple liquid impregnationreduction method, and further investigated for catalytic hydrolysis of ammonia borane and methylamine borane. Among all the catalysts tested, 1.12 wt% Ru/MCM-41 exhibits the highest catalytic activity, with turnover frequency value of 288 min^-1.