微波消解样品-氢化物发生-原子荧光光谱法测定海贝中硒

海贝样品经硝酸和过氧化氢微波加热消解,用氢化物发生-原子荧光光谱法测定其中硒的含量。使用溶于5g·L~（-1）氢氧化钾溶液中的10g·L~（-1）硼氢化钾溶液与溶液中硒离子反应生成氢化物。试样溶液中加入抗坏血酸消除硝酸的干扰。在优化的试验条件下,硒的质量浓度在600μg·L~（-1）以内与其荧光强度呈线性关系;方法检出...     

DMF催化碳酸乙烯酯与苯酚合成苯氧乙醇研究

以N,N-二甲基甲酰胺（DMF）为催化剂,研究了物料比、催化剂用量、温度、时间等工艺参数对苯酚（PhOH）与碳酸乙烯酯（EC）合成苯氧乙醇（POE）的影响,优化了工艺参数;研究了低浓度NaOH水溶液洗涤的方法对反应产物分离纯化效果;分别采用GC-MS和GC内标法对反应产物进行分析。      

以丙酮为溶剂提取纯化槐米中芦丁的工艺研究

以丙酮作为有机溶剂,采用加热回流的方法对槐米中的芦丁进行提取纯化。并对工艺条件如水浴温度、水浴时间、丙酮浓度以及料液比四个因素进行单因素试验和四因素三水平响应面试验设计的优化。通过碱溶酸沉和丙酮挥发两次重结晶析出的方法进行粗芦丁的纯化,进而采用高效液相色谱和核磁氢谱检测纯化后的芦丁样品。结果表明,响应面优化试验结果极显著,提取工艺的最佳条件为水浴时间29 min、丙酮浓度54%、料液比8.6 g/L、水浴温度70.4℃,芦丁提取率为(79.17±0.91)%。芦丁样品和标品核磁氢谱图基本一致,芦丁纯化结果为纯度为(96±0.81)%,纯品得率为(71±2.49)%。     

液相合成超薄TiO2纳米片微结构影响因素研究

二维纳米结构二氧化钛由于表面活性位点剧增可带来光催化活性的显著提高.本文通过液相法在低温条件下合成大尺寸TiO₂纳米片,重点研究溶液中硝酸浓度、熟化温度和反应物浓度对其二维结构形成过程的影响.采用透射电子显微镜（TEM）表征样品的微观形态,并结合紫外-可见吸收光谱、X射线衍射谱（XRD）、X射线光电子能谱（XPS）和傅立叶变换红外光谱分析样品的微结构性质.采用光催化还原Cr （VI）作为指示反应,评估各制备参数对二氧化钛光催化性能的影响.结果表明,硝酸浓度为0.0217~0.0721 mol·L^-1的样品在0~4℃条件下胶溶及熟化时可得到具有显著量子尺寸效应的超薄锐钛矿型TiO₂纳米片;硝酸浓度过高引起样品晶型和形态的转变,过低导致胶溶时间延长;熟化温度超过4℃会破坏二维结构的形成;提高反应物中乙醇的用量有助于分散水解产物,促进胶溶和二维结构的形成进程.     

气流吹扫-注射器微萃取-全二维气相色谱法用于原油组分的表征

建立了气流吹扫-注射器微萃取（GP-MSE）与全二维气相色谱/飞行时间质谱（GC×GC/TOFMS）联用分析原油成分的方法。为了找到适用于原油样品分析的GP-MSE条件,用饱和烃混合标准溶液和15种芳烃的混合标准溶液进行了条件优化,得到的最佳条件如下:取样量5 mg、萃取溶剂正己烷20 μ L、载气流速2 mL/min、加热时间3 min、加热温度300 ℃、冷凝温度-2 ℃。处理后的样品在全二维色谱/飞行时间质谱上进样分析,得到了满意结果。方法的检出限为34~93 μg/L,线性相关系数（R²）>0.99,对50种烃类化合物的回收率在82.0%~107.3%之间,相对标准偏差<10%（n=5）。结果表明GP-MSE-GC×GC/TOFMS法是一种新型绿色、高效、灵敏的分析方法,非常适合原油中挥发性与半挥发性组分的分析。     

硝酸对N,N-二甲基羟胺γ-辐解及液态辐解产物的影响

N,N-二甲基羟胺(DMHA)是用于动力堆乏燃料后处理U与Pu和Np分离的新型无盐还原剂, 本文研究了硝酸对DMHA γ-辐解及液态辐解产物的影响. 研究结果表明: 在U、Pu分离循环和Pu纯化循环的辐照剂量下, 在0.3-1.0 mol·L^-1的硝酸溶液中, 0.1 和0.5 mol·L^-1 DMHA具有较好的辐照稳定性. 当吸收剂量为5-25kGy时, DMHA硝酸溶液的液态辐解产物主要有单甲基羟胺、甲醛、甲酸和亚硝酸. 有机物的浓度远远高于亚硝酸浓度, 且随着剂量和硝酸浓度的增加而增大. 对于相同的硝酸浓度和剂量, 0.1 mol·L^-1 DMHA辐解产生的一甲基羟胺的浓度高于0.5 mol·L^-1 DMHA, 但前者辐解产生的甲醛浓度低于后者; 当硝酸浓度较高时, 0.1 mol·L^-1 DMHA辐解产生的甲酸浓度高于0.5 mol·L^-1 DMHA. 亚硝酸浓度与硝酸浓度及剂量的关系取决于起始DMHA和硝酸浓度.     

磷酸化油菜秸秆纤维素吸附剂的制备及对溶菌酶的吸附

以天然产物油菜秸秆纤维素粉作为基质,二甲基甲酰胺为交联剂,磷酸为修饰剂,制备了新型磷酸化油菜秸秆纤维素生物吸附剂。用红外光谱、透射电子显微镜及X射线光电子能谱,对油菜秸秆纤维素和磷酸化油菜秸秆纤维素吸附剂进行表征。研究了油菜秸秆纤维素粉改性前后对溶菌酶的吸附,包括吸附溶液的pH值、溶菌酶的初始浓度、吸附时间、温度及NaCl的浓度等因素对吸附的影响。结果表明,在温度25℃,pH值7.4,吸附时间10h的条件下,磷酸化油菜秸秆纤维素粉微球对溶菌酶的吸附容量为451.71 mg·g-1,而未修饰油菜秸秆纤维素粉微球对溶菌酶的吸附容量只有332.43mg·g-1。在优化条件下用修饰吸附剂从鸡蛋清中分离纯化溶菌酶,纯化倍数为19.8,收得率为51.3%。     

阳离子改性壳聚糖的合成工艺

弱碱性条件下,在壳聚糖（CTS）上引入2-羟丙基三甲基氯化铵（CTA）基团,使其阳离子化。采用正交试验通过测定合成产物的取代度确定其最佳合成条件,再用红外光谱对产物结构进行表征。结果表明：CTS/CTA质量比=1∶5,溶胀时间60 min,碱化温度35℃,反应温度60℃,反应时间9 h为该工艺的优化条件,在此条件下合成...     

铅与硝酸反应及影响因素

铅与硝酸的反应比较复杂,在无机化学教材和相关资料中对铅与硝酸反应的阐述不一致,这将不利于学生在无机化学学习中对铅的基本性质的掌握。针对无机化学教材中存在的问题,本文通过大量实验探究了铅与硝酸反应的条件以及硝酸浓度、反应温度、反应时间等对铅与硝酸反应的影响,并考查了硝酸铅在不同浓度硝酸中溶解度的变化,利用红外光谱(IR)和X射线粉末衍射(XRD)对铅与浓硝酸的反应产物进行了表征,明确了铅易溶于稀硝酸而在浓硝酸中溶解度小的实质。     

高锰酸盐指数测定时的质量控制和数据处理

高锰酸盐指数（简称指数）是一个相对的条件性指标,其测定结果与溶液的酸度、高锰酸钾的浓度、加热温度和时间均有关。     

Gels from a semifluorinated n-alkane in fluorinated solvents as a probe for intermolecular interactions

Diblock semifluorinated n-alkanes can form aggregates and gels in fluorinated solvents. We have investigated the thermal behavior of binary mixtures comprising F(CF₂)₈(CH₂)₁₆H and fluorinated solvents. The solvents were perfluorohexane, perfluoroheptane, perfluorooctane, perfluorooctyl bromide, perfluorodecalin, and perfluorotributylamine. The phase diagrams were used to calculate the activity coefficients of the two components and the main excess thermodynamic functions. The solubility and self-assembly behavior of F₈H₁₆ in the fluorinated solvents are related to the different solute–solvent dispersion interactions that depend on the polarizabilities and ionization potentials of the interacting species, and on the structural properties of the solvent.     

Studies on the Formation of Catalytically Active PGM Nanoparticles from Model Solutions as a Basis for the Recycling of Spent Catalysts

The paper presents basic studies on the precipitation of platinum, palladium, rhodium, and ruthenium nanoparticles from model acidic solutions using sodium borohydride, ascorbic acid, and sodium formate as reducing agents and polyvinylpyrrolidone as a stabilizing agent. The size of the obtained PGM particles after precipitation with NaBH₄ solution does not exceed 55 nm. NaBH₄ is an efficient reducer; the precipitation yields for Pt, Pd, Ru, Rh are 75, 90, 65 and 85%, respectively. By precipitation with ascorbic acid, it is possible to efficiently separate Pt, Rh, and Ru from Pd from the two-component mixtures. The obtained Pt, Pd, and Rh precipitates have the catalytic ability of the catalytic reaction of p-nitrophenol to p-aminophenol. The morphological characteristic of the PGM precipitates was analyzed by AFM, SEM-EDS, and TEM.     

PMDA-BPDA-HAB聚苯并噁唑的合成及耐热性

PMDA-BPDA-HAB聚苯并噁唑的合成及耐热性;均苯四甲酸二酐;联苯四羧酸二酐;二羟基联苯胺;聚酰亚胺;聚苯并噁唑;耐热性     

HCOO在Cu(110)、Ag(110)和Au(110)表面的吸附

采用密度泛函理论(DFT)以及广义梯度近似方法(GGA)计算了甲酸根(HCOO)在Cu(110)、Ag(110)和Au(110)表面的吸附. 计算结果表明, 短桥位是最稳定的吸附位置, 计算的几何参数与以前的实验和计算结果吻合. 吸附热顺序为Cu(110)(-116 kJ·mol-1)>Ag(110)(-57 kJ·mol-1)>Au(110)(-27 kJ·mol-1), 与实验上甲酸根的分解温度相一致. 电子态密度分析表明, 吸附热顺序可以用吸附分子与金属d-带之间的Pauli 排斥来关联, 即排斥作用越大, 吸附越弱. 另外还从计算的吸附热数据以及实验上HCOO的分解温度估算了反应CO2+1/2H2→HCOO的活化能, 其大小顺序为Au(110)>Ag(110)>Cu(110).     

Transition metal complexes of the tripodal ligand 4-(2′-pyridylmethyl)-4-azaheptane-1,7-diamine. Crystal structures of [CuLCl]ClO4 and [NiL(MeCN)2](ClO4)2

The tripodal ligand 4-(2′-pyridylmthyl)-4-azaheptane-1,7-diamine has been prepared by reaction of 2-aminemethyl pyridine with acrylonitrile, followed by the reduction of the nitrile groups. Copper(II), nickel(II), zinc(II), cobalt(III) and chromium(III) complexes of the ligand have been prepared and characterized and the crystal structures of the complexes [CuLCl]ClO₄ and [NiL(MeCN)₂](ClO₄)₂ determined. The copper complex is five coordinate with approximate square pyramidal stereochemistry with the apical position occupied by a primary amine donor. The nickel complex is octahedral with the pyridine nitrogen donor lying trans to an acetonitrile ligand.     

SYNTHESIS AND CHARACTERIZATION OF METAL COMPLEXES WITH AMPICILLIN

Abstract

The reaction, in water, of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) ions with sodium ampicillinate at room temperature has allowed isolation of dimers with the following general formula [M(amp)Cl]₂ × nH₂O (n = 1.5?3.2). The complexes were characterized by elemental analyses, conductivity measurements, magnetic susceptibilities and spectroscopic methods (IR, Raman, EPR and UV-Visible). A dinuclear structure based on octahedrally coordinated metal ions is proposed.     

Magnetism of metal-nitroxide compounds involving bis-chelating imidazole and benzimidazole substituted nitronyl nitroxide free radicals

Coordination compounds based on imidazole and benzimidazole substituted nitronyl nitroxide radicals with transition metal ions and trivalent lanthanide ions are described from the perspective of their magnetic properties.For the transition metal compounds the crystal structures show various metal-nitroxide dimensionalities including mononuclear (0D), one-dimensional (1D) and two-dimensional (2D) complexes. The mononuclear complexes were isolated with most metal ions of the first transition series. One copper(II) complex shows a copper(II)-radical ferromagnetic coupling (J = +75 cm⁻¹) while for the other mononuclear compounds, mainly with manganese(II), the metal-radical interactions are antiferromagnetic. The one-dimensional and two-dimensional complexes are manganese(II) compounds which show canting effects leading to weak ferromagnetism.For the trivalent lanthanide ions [La(III), Gd(III) and Eu(III)], three series of mononuclear complexes were obtained in which the metal center is bound to four, two or one nitroxide radicals depending on the counter ions and ancillary ligands. Unexpectedly, in most gadolinium(III) complexes, the Gd(III)-radical interactions were found to be antiferromagnetic in contradiction with other foundings and previous theoretical models. In support to the magnetic studies, the optical properties of the lantanide complexes have also been investigated and are briefly described.     

New Complexes of Ditopic Ligands with “d” and/or “s” Metal Ions

Abstract

The asymmetric compartmental macrocycles containing one N₂O₂ or N₃O₂ Schiff base and one O₂O₃ or O₂O₄ crown-ether like chamber, have been obtained by condensation reaction of the formyl precursors 3,3′-(3-oxapentane-1, 5-diyldioxy) bis (2-hydroxybenzaldehyde) or 3,3′-(3,6-dioxaoctane-1,8-diyldioxy)-bis(2-hydroxybenzaldehyde) with ethyl ethylenediamine (H₂L_A, H₂L_C), 1,5-diamino-3-azamethylpentane(H₂L_B, H₂L_D), also in the presence of metal ions as templating agents. These ditopic ligands, with dissimilar coordination sites, have been designed and used for the selective complexation of “d” and/or “s” metal ions, respectively into the Schiff base and the crown ether chamber. The selectivity of these processes strongly depends on the size and on the donor atom sets of the sites. The possibility to obtain mononuclear M(L)·nH₂O (M = Ni²⁺, Cu²⁺, Co²⁺), Mn(L)(CH₃COO)·nH₂O or Na(L) and hetero-dinuclear MNa(L)(CH₃COO) (M = Ni²⁺, Cu²⁺, Co²⁺) and MnNa(L)(CH₃COO)₂·nH₂O complexes has been successfully tested. The ligands and complexes have been characterized by ir, nmr, mass spectrometry and magnetic susceptibility measurements.

Two of the ligands used for the preparation of the solid samples, i.e., to H₂L_A and H₂L_B, have been employed to study complexation reactions of Co(II) and Na(I) in solution. In order to obtain information on the ligand preorganization effect toward the complex stabilities, a simpler open chain parent compound of H₂L_B (H₂L_E) has been also prepared and studied. FT-IR spectra show that H₂L_A is unable to complex Na⁺ in DMSO while the complexation reactions of Na⁺ by H₂L_B and of Co²⁺ by H₂L_A take place with slow kinetics. Therefore, thermodynamic data have been obtained only for the systems Co²⁺/H₂L_B and Co²⁺/H₂L_E. The thermodynamic parameters obtained for the complexation reactions show that the pre-organization of the donor atoms in H₂L_B does not add a significant contribution to the stabilities of the complexes. Both H₂L_B and H₂L_E form in DMSO 1:1, 1:2 and 1:3 = M:L complexes with very similar stabilities and almost equal enthalpies of formation. Physico-chemical studies suggest besides that the slow reaction of Na⁺ with H₂L_B is probably due to the formation of a 1:1 complex where the metal cation, initially occupying the O₃ cage of the ligand, slowly binds also the oxygens of the phenolic moieties. Spectral and calorimetric data on solutions containing H₂L_B and different Co²⁺: Na⁺ ratios evidence that in DMSO no stable heterodinuclear complexes form when the neutral ligand is considered.     

具有聚集诱导发光性质的近红外荧光染料

聚集诱导发光(AIE)现象的发现为解决传统有机荧光分子在高浓度和聚集形态下存在的荧光猝灭问题提供了最佳方案,并实现了在光电器件、化学传感、生物成像和靶向治疗等众多领域的广泛应用.随着对AIE 发光机理研究的不断深入,AIE 分子体系得到了极大的扩展.其中,一类具有给体-受体结构的AIE分子能够显著降低分子能隙,使发光分...     

Simple,Selective, and Sensitive Spectrophotometric Method for Determination of Trace Amounts of Nickel（Ⅱ）, Copper （Ⅱ）, Cobalt （Ⅱ）, and Iron （Ⅲ） with a Novel Reagent 2-Pyridine Carboxaldehyde Isonicotinyl Hydrazone

A selective and sensitive reagent of 2-pyridine carboxaldehyde isonicotinyl hydrazone（2-PYAINH） was synthesized and studied for the spectrophotometric determination of nickel, copper, cobalt, and iron in detail. At a pH value of 7.0, 9,0, 9.0, and 8.0, respectively, which greatly increased the selectivity; nickel, copper, cobalt, and iron reacted with 2-PYAINH to form a 1：2 yellow-orange, 1：2 yellow-green, 1：2 yellow and 1：1 yellow complexes, with absorption peaks at 363, 352, 346, and 359 nm, respectively. Under the optimal conditions, Beer＇s law was obeyed over the ranges of 0.01-1.4, 0.01-1.5, 0.01-2.7, and 0.01-5.4 mg/L respectively. The apparent molar absorptivity and Sandell＇s sensitivities were 8.4×10^4, 5.2×10^4, 7.1×10^4, and 3.9×10^4 L·mol^-l·cm^-1, respectively, and 0.00069, 0.0012, 0.00078, and 0.0014 μg·cm2, respectively. The detection limits were found to be 0.001, 0.002, 0.003, and 0.01 mg/L, respectively. The detailed study of various interfering ions to make the method more sensitive was carried out and selective and several real samples were analyzed with satisfactory results.