适于测定苄胺的可逆光敏膜的研究

本文报道了一种测定苄胺的可逆光敏膜.将作为苄胺离子载体的联萘冠醚和亲脂的pH指示剂,结合在增塑的PVC膜中,苄胺离子与氢离子在膜相的竞争引起膜的吸光值变化.报道了该传感器的响应特性,推导了有关的理论关系式.     

香豆素-3-甲酰苄胺的合成及晶体结构

以香豆素-3-甲酸乙酯(1)为前驱体,与苄胺发生酯的胺解反应,合成了酰胺型香豆素衍生物香豆素-3-甲酰苄胺,通过红外光谱、核磁共振光谱以及X-射线单晶衍射对其进行了结构表征。晶体结构结果表明,每个晶胞中包含2个香豆素-3-甲酰苄胺分子,两个分子之间通过C5-H5···O3和C7-H7···O3氢键相互作用形成环状二聚体,再进一步通过C2-H2···O1氢键作用组装成一维链状结构。     

聚乙烯苄胺树脂合成条件的研究

利用NICOLET 5DX红外光谱仪研究了聚乙烯苄胺树脂的合成条件和反应历程。结果表明,在适当的条件下采用不同合成方法均可得到聚乙烯苄胺树脂。在某些条件下将引起明显的副反应发生。     

4-(4-甲基苯氧基)苄胺的合成

甲基苯氧基苄胺;农药;4-(4-甲基苯氧基)苄胺的合成     

氮掺杂氧化石墨催化苄胺氧化

酰胺类化合物是重要的化工原料和生物医药合成的中间体,但其制备大部分需要使用贵金属催化剂,因此,发展廉价金属乃至非金属催化剂具有重大意义.本文使用化学气相沉积法合成了氮掺杂的层状氧化石墨材料,并将其应用于苄胺氧化反应中,实现了液相中酰胺合成的非金属催化过程.在水相中可以活化氧气较高产率地生成亚胺化合物N-苄亚甲基苄胺,并且成功实现了在氨水反应介质中高转化率和选择性地生成苯甲酰胺.此外,对反应中的影响因素进行了逐一研究,并从多方面探究了该反应中氨水的作用以及反应最可能的历程,提出了一条经过包括亚胺在内的多个中间产物的反应路径.本工作对于研究碳氢键的活化过程以及拓宽碳催化领域进行了有益的尝试.     

(R)-α-取代苄胺的立体控制合成

通过(+)-樟脑酮亚胺体系的不对称反应已有不少文献报道。近年来,我们曾先后用(+)-樟脑缩甘氨酸特丁酯和(+)-樟脑缩苄胺体系作手性模板,合成了多种生理活性的(R)-α-氨基酸,(R)-α-取代苄胺和β-氨基醇。但产物的光学收率除个别在90％以上外,多数都不高。因此,为寻找具有高的立体选择性的手性模板,我们对天然(+)-樟脑进行结构改造,按Bartlett's方法将樟脑氧化成10-樟脑酸(1),经酰氯化后,在二氯甲烷     

甲氧苄胺嘧啶药物的非破坏分析

将偏最小二乘（ＰＬＳ）法同近红外漫反射光谱法结合，非破坏分析了粉末药品甲氧苄胺嘧啶。讨论了波长对ＰＬＳ定量预报能力的影响。校正样品和预测样品的预测结果相对标准误差分别为０．３３％和１．３９％。     

WO3/4,4′-联苄胺光致变色超晶格薄膜的研究

无机-有机超晶格薄膜材料的制备以及性质研究是目前国际上的研究热点.基于超分子化学自组装原理,利用自组装技术构建含有有机分子的光致变色纳米超晶格薄膜材料,是一种研制光致变色功能薄膜材料的新方法.此项研究能够为研制变色响应速度快的、稳定性好的、变色可调控的光致变色器件奠定基础,具有深远的意义和重要的科学价值.本文采用溶液中相反电荷聚电解质自组装的方法(PEs法)[1],制备了WO3/4,4′-联苄胺超晶格薄膜;采用紫外可见吸收光谱和小角X-射线衍射谱对薄膜的层状结构和分子的排列方式进行了研究.     

人工神经网络—近红外光谱法用于甲氧苄胺嘧啶粉末药品的非？…

近红外(NIR)光谱分析技术已应用于制药、化妆品、烟草、食品、化学药品、聚合物、纺织品、油漆涂料、煤炭和石油工业等各个领域的质量监控.近年来,NIR光谱分析技术也应用于药品分析中,因该方法具有非破坏性,样品不需要复杂的预处理和分离即可直接测定.它可对药物进行定性和定量测定以及多晶、光学异构体和湿度的测定.近红外光谱法用于无损非破坏测定胶囊类以及片剂的研究已有报道[1,2].NIR光谱在使用中也有一定的局限性,主要是结构复杂,谱图重叠多,在进行定性和定量分析中需采用一定的数据处理才能获得准确可靠的分析结果.在定量分析中,…     

竹红菌甲素半醌自由基的变化特点

通过研究竹红菌甲素半醌负离子自由基衰减的动力学,建立了甲素半醌自由基在624nm的可见吸收强度和ESR信号强度的平行关系.在624nm的可见吸收属于甲素半醌自由基的吸收.这个研究结果对研究甲素的半醌自由基具有实用意义.讨论了还原型谷胱甘肽存在下光诱导所产生的甲素 半醒自由基的衰变特点.     

Preliminary study on the photoproduction of hydroxyl radicals in aqueous solution with Aldrich humic acid, algae and Fe(III) under high-pressure mercury lamp irradiation

Under a high-pressure mercury lamp (HPML) and using an exposure time of 4 h, the photoproduction of hydroxyl radicals (*OH) could be induced in an aqueous solution containing humic acid (HA). Hydroxyl radicals were determined by high-performance liquid chromatography using benzene as a probe. The results showed that *OH photoproduction increased from 1.80 to 2.74 microM by increasing the HA concentration from 10 to 40 mg L(-1) at an exposure time of 4 h (pH 6.5). Hydroxyl radical photoproduction in aqueous solutions of HA containing algae was greater than that in the aqueous solutions of HA without algae. The photoproduction of *OH in the HA solution with Fe(III) was greater than that of the solution without Fe(III) at pH ranging from 4.0 to 8.0. The photoproduction of *OH in HA solution with algae with or without Fe(III) under a 250 W HPML was greater than that under a 125 W HPML. The photoproduction of *OH in irradiated samples was influenced by the pH. The results showed that HPML exposure for 4 h in the 4-8 pH range led to the highest *OH photoproduction at pH 4.0.     

PHOTOSENSITIZATION BY ANTITUMORAGENTS–6. PRODUCTION OF SUPEROXIDE RADICAL AND HYDROGEN PEROXIDE DURING ILLUMINATION OF DIAMINOANTHRACENEDIONES IN THE PRESENCE OF NADH IN AQUEOUS SOLUTIONS: AN EPR STUDY

Abstract— Photosensitizing capabilities of anthracenedione anticancer agents to oxidize NADH in aqueous solutions have been studied by EPR and spin trapping techniques. It is demonstrated that 1,4-diamino substituted anthraquinones, like mitoxantrone and ametantrone, do not photosensitize NADH oxidation while 1,5- and l,8-bis[[(diethylamino)ethyl]amino]anthraquinones do, undergoing simultaneous one-electron reduction to their semiquinone radical forms upon illumination with visible light. In aerated aqueous solutions the reaction leads to the production of superoxide ion and hydrogen peroxide.     

PHOTOCHEMISTRY OF HYPOCRELLIN A (Ⅶ)——PHOTO-INDUCED ONE-ELECTRON REDUCTION OF HYPOCRELLIN PIGMENTS

The photo-induced one-electron reduction of hypocrellin A (abbreviated as HA) and hy-pocrellin B (abbreviated as HB) in the presence of cysteine or ascorbic acid has been studied in this paper. The semiquinone radical anions of HA and HB obtained from the photo-reduction of HA and HB respectively, and the following protonation and disproportionation of these radical anions were detected via the ESR and UV-Vis spectra. Through comparison of their UV-Vis spectra with those of the chemically synthesized compounds of similar structures, it has been suggested that the metastable products formed after the acceptance of net two electrons and two protons in the photoreduction of HA and HB were tetrahydroxyl-per-ylene derivatives.     

SENSITIZED PHOTOOXIDATION OF AMINO ACIDS: EFFECTS ON THE REACTIVITY OF THEIR PRIMARY AMINE GROUPS WITH FLUORESCAMINE AND O-PHTHALALDEHYDE

Abstract— The photooxidation of his, met, trp and tyr with methylene blue and eosin as sensitizers resulted in a loss of primary amine reactivity as measured with fluorescamine and o-phthalaldehyde. The rates of oxygen uptake and of loss of primary amine reactivity with illumination was characteristic for each amino acid. Glycine did not photooxidize and showed no change in primary amine reactivity. Primary amine reactivity of the N -acetyl derivatives of these amino acids was negligible and during photooxidation the reactivity increased slowly with N -acetylhis and N -acetyltrp while the reactivity of N -acetylmet and N -acetyltyr did not change. Imidazole and indole also showed a slow increase in primary amine reactivity during sensitized photooxidation. The rate of oxygen uptake and primary amine reactivity loss during the sensitized photooxidation of his and met was markedly increased in deuterium oxide. This indicated that singlet oxygen was involved. Radical scavengers did not affect the rates indicating that free radical intermediates were not involved. Primary amine reactivity loss is probably due to intra- and/or inter-molecular secondary dark reactions between unknown initial oxygenation products and primary amino groups.     

Complex formation of D-mannonaphto-18-crown-6-ether and enantiomers of phenylalanine in water studied by different physochemical methods

Complex formation of D-mannonaphto-18-crown-6-ether 1 with D- and L-phenylalanine (Phe) and their derivatives was studied using conduction and titration microcalorimetry in aqueous solution, and solvent–solvent (water–chloroform) extraction. The thermal effects accompanying the complexation process were determined, but the chiral recognition effects were very small. The chiral differentiation of amino acid was observed in the experiments of the extraction from water to chloroform phase containing chiral receptor.     

Electron transfer from aromatic amino acids to triplet quinones

The photoreduction of 1,4-benzoquinone, 1,4-naphthoquinone, 9,10-anthraquinone (AQ) and several methylated or halogenated derivatives in argon-saturated acetonitrile-water mixtures by indole, N-acetyltryptophan and N-acetyltyrosine was studied by time-resolved UV-vis spectroscopy using 20 ns UV laser pulses. The quinone triplet state is quenched by the aromatic amino acids and the rate constants are (1-5)x10(9)M(-1)s(-1). The semiquinone radical anion Q.(-) is the major observable transient after electron transfer from amino acids to the quinone triplet state. Termination of Q.(-) and amino acid derived radicals takes place in the mus-ms range. The effects of structure and other specific properties of quinones and amino acids are discussed. The radicals are subjects of intercept with oxygen, whereby hydrogen peroxide is eventually formed. The quantum yield of oxygen uptake Phi(-O2) as a measure of formation of hydrogen peroxide increases with increasing amino acid concentration, approaching Phi(-O2) for AQ in air-saturated solution.     

Complexation of hypocrellins and bivalent metals and one-electron reduction of the complexes with electron donor

The complexation of HA (or HB) with bivalent metals was examined by UV-Vis andNMR spectroscopy, and all of the complexes obtained have a metal-ligand ratio of 1:1.Thephotoinduced reduction of the complexes of HA-Zn~(2+) and HA Mg2+ (or HB-Zn~(2+), HB-Mg2+)in the presence of 1-benzyl-1,4-dihydro-nicotinamide as the electron donor was investigated byUV-Vis and ESR spectroscopy. The studies demonstrated that illumination of the complexes ofHA(HB)-Zn~(2+) and HA(HB)-Mg~(2+) led to the accumulation of the chelated semiquinone radicalanions.     

Radical kinetics and characterization of the free radicals in gamma irradiated red pepper

Kinetic behaviors and characterization of the natural and γ-induced radicals in irradiated red pepper have been investigated by electron spin resonance (ESR) spectroscopy to explore the possibility of using this technique in detecting irradiated red pepper and to evaluate the eventual dosimetric features of this widely used food. Unirradiated samples exhibited a single resonance line centered at g=2.0050±0.0005. Photo-exposure of the samples was found to increase the signal intensity. An increase in temperature created a drastic decrease in the concentration of natural radicals responsible for the single resonance line. Irradiation was observed to induce increases in the intensity of single resonance line (signal I) and a radiation specific doublet and/or triplet (signal II) also centered at g=2.0050 but detectable only at high spectrometer gains. The intensities of both signals increased with increasing radiation dose. The signals I and II were found to decay with different rates depending on the temperature. The results of a fitting procedure applied to the experimental signal decay curves and those obtained from room temperature spectra simulation calculations were used together to determine radical species and their spectral characteristics giving rise to the observed experimental spectra. Four radical species, three carbohydrate and one semiquinone radical assigned as radicals A, B, C and D, respectively, were found to best explain the experimental results. All the radicals show large g and hyperfine splitting anisotropies varying between g=2.0028–2.0062 and 1.07–2.58 mT, respectively. The half lives of the radicals were found to depend strongly on temperature. The activation energy calculated using temperature dependent half-life data were the highest for radical A (33.68 kcal/mol) and smallest for radical C (11.83 kcal/mol).     

紫外光下纳米TiO2 薄膜亲水性机理的电化学研究

The nanometer films of TiO2 were prepared by sol-gel method on ITO（Indium-tin oxide,SnO2:In） substrate. The TiO2 film was the anatase phase with a particle size of 100 nm from the measurements of X-ray diffraction and AFM（Atomic-Force-Microscope）. Electrochemical characteristics of ITO/ TiO2 electrode under UV（ultraviolet）irradiation were investigated using the method of cyclic voltammetry. A new oxidative peak was observed at 0.035 V when the TiO2 electrode was irradiated by 253.7 nm UV light for a certain time. The peak current increased with the irradiation time. It was assumed that the new oxidative peak resulted from Ti3+,which was formed during the UV illumination. The changes of hydrophilicity of the TiO2 thin film on ITO under UV light were also observed. It was assumed that the changes of hydrophilicity of the films may be related with the formation of Ti3+ on the surface when the film was irradiated by UV light.