946 resultados para 2,3-dicloro-6,7-dinitroquinoxalina
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A simple, large scale, and one-step process for the preparation of tris(2,2'-bipyridyl)ruthenium(I) (Ru(bpy)(3)(2+)) doped SiO2@carbon nanotubes (MVNTs) coaxial nanocable used for an ultrasensitive electrochemiluminescence (ECL) is presented for the first time. More importantly, a directly coated as-formed functional material on ITO electrode surface exhibits excellent ECL behavior, good stability, and high sensitivity in the presence of tripropylamine (TPA). This novel functional material will find potential applications in biosensor, electrophoresis and electroanalysis.
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An efficient synthetic procedure for substituted 2,3,6,7tetrahydrothiopyrano [2,3-b] thiopyran-4,5 -diones by a double annulation strategy is described. The ring systems are made in good yields from readily available dialkenoylketene dithioacetals in the presence of either sodium sulfide nonahydrate/N,N-dimethylformamide (DMF) or a sodium hydride/DMF/amine system.
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由 5-(2-乙酰基-1-甲硫基-3-羰基-亚丁基)-丙二酸亚异丙酯 (1)与邻苯二胺及乙酸镍()经一步反应合成了3{1-[2-( -3-羟基-1-甲基-2-亚丁烯氨基)-苯亚氨基 ]-乙基} 4-甲硫基-2,4-戊二烯-2-醇(3)的不对称四齿 Schiff碱镍()配合物(2),X射线衍射结果表明,配合物 2属单斜晶系,P21/C空间群.a=1.1476(2)nm,b=1.1782(2)nm,c=1.4810(3)nm;β=111.73(2)°,V=1.8602(7)nm3,Z=4,Rf=0.0535.电化学(循环伏安)测定结果表明,该配合物在测定条件下(阳极峰电位为1.1)发生了不可逆的氧化-还原反应.
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铜激活的硫化锌 (Zn S∶ Cu)和铕激活的硫化钙 (Ca S∶ Eu)是最早获得应用的蓝色和红色长余辉材料 .随后 ,相继发现了铝酸盐体系和硅酸盐体系两大类长余辉荧光材料 [1~ 3 ] .这两类长余辉荧光材料在发光亮度、余辉时间、稳定性方面都较前述硫化物系列长余辉荧光材料有很大提高 ,从而具有非常广阔的应用前景和应用范围 [4~ 6] .但这两类长余辉荧光材料的发光颜色一般为蓝紫、蓝或黄绿 ,没有红色发光现象 .随着研究的深入 ,人们发现了稀土元素激活的碱土钛酸盐红色长余辉荧光材料 ,这种荧光材料在发光亮度及余辉上都有明显的提高 [7,8] ,而且解决了硫化物不稳定的缺点 .近年来才发展起来的以碱土金属氧化物为发光基质 ,以 Eu3 + 为激活剂的红色长余辉荧光材料进一步提高了余辉亮度及时间 [9] .传统碱土硫化物类磷光体有较宽的激发谱带 ,可在不同的光源下激发 .但它的稳定性较差 ,必须进行工艺后处理才能得到应用 .其它几类磷光体的激发光源谱带较窄 ,仅限于紫外光源 ,因此使其应用范围受到限制 .目前已报道的各种长余辉红色荧光材料在余辉时间方面有较大的差异 ,从十几分钟到几百分钟不等 ,各类红色磷光...
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合成了NdnSrFenO3n+1(n=1,2 ,3,∞ ) 系列复合氧化物 ,其中Nd3SrFe3O10 是首次合成 ,并研究了其晶体结构 ,IR谱以及 30 0~ 110 0K之间的电性质和磁性质。相对于NdSrFeO4 ,Nd2 SrFe2 O7中ab平面上的Fe O键较短而c轴方向的Fe O键较长 ;而NdFeO3中只有一种Fe O键 ,在 30 0~110 0K之间 ,NdSrFeO4 ,显反铁磁性行为 ,Nd2 SrFe2 O7表现为亚铁磁性 ,而Nd3SrFe3O10 和NdFeO3为顺磁性。随着n值的增大 ,该系列氧化物电阻率增大 ,这可能是系统四价Fe离子浓度减小的结果。
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用 Siemens P4四圆衍射仪,测得了1,4-二丙氧基-2,3-二氰基萘的晶体结构。晶体属单斜晶系,空间群为 C2/C。晶格参数 a=14.987(3)A,b=10.527(2),c=11.755(2),β=118.98°(3),晶胞体积 V=1622.4(6)3,Z=4,Dc=1.205Kg/m~3,μ(MoK_α)=0.079mm~(-1),F(000)=624,T=293(2)K_o晶体结构应用直接法,解出最后的偏离因子 R=0.0554[1425个Ⅰ≥2σ(Ⅰ)衍射点]。结构分析表明,萘环的1,4和2,3位碳原子上的氢原子分别被丙氧基和氰基所取代,由于取代基的引入使萘环的结构有所改变。
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本文报道了6种新的丙烯酰胺衍生物的EI谱。在精确质量测量和B/E,B~2/E联动扫描亚稳离子测定的基础上,着重讨论了该类化合物的共同质谱特征:如分子离子失去H_2O的成环反应;产物离子的开环反应;分子内的氢重排反应等。同时,利用Hammett方程讨论了化合物中N-苯基端苯环上不同取代基对特定碎片离子强度的影响
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二苯乙炔和金属锂在乙醚中反应得到1,4-二锂四苯基丁二烯,再与无水氧化希土反应得到了两种系金属条-2,3,4,5-四苯基环戊二烯环状化合物。通过元素分析、红外光谱、核磁共振谱、热失重及电子能谱的分析,对所合成的化合物进行了表征;并对化合物的水解产物作了红外光谱、质谱和核磁共振谱分析,确认下列两种化合物的存在:
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Protein tyrosine phosphatase 1B (PTP1B) plays an important role as a negative regulator and has been proved to be an effective target for the treatment of type 2 diabetes mellitus. Bis-(2,3-dibromo-4,5-dihydroxyphenyl)-methane 7 was first reported as a natural bromophenol with significant inhibition against PTP1B which was isolated from red algae Rhodomela confervoides. Intrigued by its astonishing activity (IC50 = 2.4 mu mol/L), compound 7 was synthesized with the overall yield of 24% and evaluated for its PTP1B inhibitory activity compared with natural compound. (C) 2008 Li Jun Han. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
Resumo:
The title compound, ( C19H15N4)(2)[ CdCl4], a salt comprising two 2,3,5-triphenyl-substituted tetrazolium cations and a tetrachloridocadmate(II) anion, was synthesized by hydrothermal methods. In the anion, the Cd-II ion is tetrahedrally coordinated by four chloride anions. In the crystal structure, four cations and two anions pack into inversion-related subunits linked by C-H center dot center dot center dot Cl and offset pi-stacking interactions.Each of these subunits is surrounded by six others. Intermolecular pi-pi stacking interactions between phenyl rings are observed along the a axis, with perpendicular distances between the ring planes of 3.6015 and 3.6934 angstrom.
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This paper describes the simultaneous determination of allantoin, quercetin, and 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid (MTCCA) in Nitraria tangutorum Bobr seed by HPLC-APCI-MS and CE (capillary electrophoresis) methods. The final optimized chromatographic conditions were investigated in a reversed-phase Eclipse XDB-C8 column (150 x 4.6 mm, 5 mu m). A seventeen-minute gradient elution, (A: aqueous acetonitrile 20% (v/v); B: aqueous acetonitrile 60% (v/v); C: pure acetonitrile 100%) at a flow rate of 1.0 mL/min was selected for the separation of three natural products with diode array detection (DAD) at 220 nm. A CE experiment was carried out in a fused silica capillary with 32 mmol/L boric acid (pH 10), 32 mmol/L SDS and acetonitrile (10.0%, v/v). The applied potential and temperature was, respectively, set at 19 kV and 25 degrees C. After development, the validation was performed in parallel for HPLC and CE, with the same standards and sample to avoid differences due to the manipulation. The validation parameters of both techniques were adequate for the intended purpose.