偏最小二乘法在原子吸收光谱分析中的应用——钴和铟的同时测定

本文用偏最小二乘法（ＰＬＳ）校正了火焰原子吸收分析Ｉｎ２５２．１３７ｎｍ对Ｃｏ２５２．１３６ｎｍ的吸收线重叠干扰,对混合样中Ｃｏ和Ｉｎ的含量进行了测定,结果令人满意。     

海底沉积物的ICP-AES分析

海底沉积物用硝酸-高氯酸-氢氟酸消解,然后用ICP-AES法同时测定常量和微量元素。研究了样品中基体元素对微量元素测定的光谱干扰,并采用干扰曲线斜率法进行干扰校正,分析批量海底沉积物样品获得满意结果。     

高纯氧化镝电感耦合等离子体原子发射光谱法摄谱分析时光谱干扰校正方法的研究

本文建立了高纯氧化镝样品ICP摄谱分析时干扰系数法校正光谱干扰的方法。测定了镝基体对14种稀土杂质元素20条灵敏分析线的干扰系数(KCT)。并有效地校正了镝基体造成的光谱干扰,获得满意的结果。     

Predicting the performance of molecularly imprinted polymers: Selective extraction of caffeine by molecularly imprinted solid phase extraction

A rational design approach was taken to the planning and synthesis of a molecularly imprinted polymer capable of extracting caffeine (the template molecule) from a standard solution of caffeine and further from a food sample containing caffeine. Data from NMR titration experiments in conjunction with a molecular modelling approach was used in predicting the relative ratios of template to functional monomer and furthermore determined both the choice of solvent (porogen) and the amount used for the study. In addition the molecular modelling program yielded information regarding the thermodynamic stability of the pre-polymerisation complex. Post-polymerisation analysis of the polymer itself by analysis of the pore size distribution by BET yielded significant information regarding the nature of the size and distribution of the pores within the polymer matrix. Here is proposed a stepwise procedure for the development and testing of a molecularly imprinted polymer using a well-studied compound—caffeine as a model system. It is shown that both the physical characteristics of a molecularly imprinted polymer (MIP) and the analysis of the pre-polymerisation complex can yield vital information, which can predict how well a given MIP will perform.     

Component reconstruction in the primary space of spectra and concentrations. Alternating regression and related direct methods

A set of methods that extract the spectral components in a chromatographic run is considered. The methods do not need libraries of previously known spectra or retention times. The methods have been developed for two-dimensional spectra but they can also be used for chromatographic analyses with a single-channel detector. The methods are direct; they do not use principal components as the starting point. Alternating regression (AR) remains in the primary space of spectra and concentrations during the calculations. Random numbers are used as the starting spectra. Regression is used to solve first for the concentrations, then for the spectra. The method uses two kinds of constraints: all spectra and concentrations are forced to be positive; and all concentration profiles are forced to a unimodal shape with a single local maximum. It is assumed that all observations are a linear sum of components. Compact alternating regression (CAR) is a new variant of the basic AR. The idea is to replace multiplication of a large matrix by two multiplications of smaller matrices. This typically speeds up the iterations by a factor of ten. AR and CAR have been successfully used with combined techniques such as gas chromatography—mass spectrometry and liquid chromatography with UV—visible detection. The reliability of the solution is checked by repeatedly injecting noise and performing the analysis several times. This produces estimates of confidence intervals. AR and CAR have recently been extended to handle single-dimensional signals. Examples are single-channel detectors such as the flame ionization detector in gas or liquid chromatography with a fixed-wavelength UV detector. A batch of samples is used as the observation matrix. As a result, one obtains both the concentrations and the elution shapes of individual chromatographic peaks.     

Iridium mediated methyl and phenyl C-H activation of 2-(arylazo)phenols. Synthesis, structure, and spectral and electrochemical properties of some organoiridium complexes

Reaction of 2-(2′,6′-dimethylphenylazo)-4-methylphenol with [Ir(PPh₃)₃Cl] in refluxing ethanol in the presence of a base (NEt₃) affords an organoiridium complex 5, where the 2-(2′,6′-dimethylphenylazo)-4-methylphenol is coordinated to iridium, via C-H activation of a methyl group, as a dianionic tridentate C,N,O-donor. Two triphenylphosphines and a hydride are also coordinated to the metal center. A similar reaction carried out in toluene affords complex 5 along with a similar complex 7, where a chloride is coordinated to iridium instead of the hydride. Reaction of 2-(2′-methylphenylazo)-4-methylphenol with [Ir(PPh₃)₃Cl] in refluxing ethanol in the presence of a base (NEt₃) affords an organoiridium complex 12, where the 2-(2′-methylphenylazo)-4-methylphenol is coordinated to iridium, via C-H activation at the ortho position of the phenyl group in the 2′-methylphenylazo fragment, as a dianionic tridentate C,N,O-donor. Two triphenylphosphines and a hydride are also coordinated to the metal center. A similar reaction carried out in toluene affords a complex 12 along with a similar complex 13, where a chloride is coordinated to iridium instead of the hydride. Structures of complexes 5, 12 and 13 have been determined by X-ray crystallography. In all these complexes, the two triphenylphosphines are trans. All these complexes show intense MLCT transitions in the visible region. Cyclic voltammetry on all the complexes shows an Ir(III)-Ir(IV) oxidation within 0.60-0.73 V vs. SCE, followed by an oxidation of the coordinated 2-(arylazo)phenolate ligand within 1.08-1.39 V vs. SCE. A reduction of the coordinated 2-(arylazo)phenolate ligand is observed within −1.10 to −1.26 V vs. SCE.     

η6-苊烯三羰基铬配合物的合成、结构及光谱性质研究

采用苊烯配体与三胺基三羰基铬在四氢呋喃中回流反应,合成了η6-苊烯三羰基铬配合物.通过元素分析、IR、1HNMR、13CNMR、MS和X射线单晶衍射对其结构进行了表征,比较了标题配合物与其自由配体的光物理行为.晶体结构分析表明,标题配合物属单斜晶系,空间群P21/c,Z=4,a=0.8719(7)nm,b=1.2436(10)nm,c=1.1504(9)nm,β=111.835(13)°,Cr(CO)3基团可与苊烯配体中的2个苯环中的任意一个配位,形成2个异构体(R,S),并以1:1的比例在其晶胞单元中反向面对面堆积,这种异构体共存于晶体中归属于Cr(CO)3基团在配体芳环之间的配位移动重排(IRHRs).     

固定波长同步荧光光谱参数的理论计算

基于荧光激发光谱和发射光谱对波长呈高斯分布的设定,本文推导出固定波长同步荧光光谱峰峰值位置、相对强度和半峰宽度等3个主要光谱参数的理论计算式。所提出的计算式应用于若干荧光物质光谱参数的计算,并和实测值、文献计算值作了对照。结果表明,和文献计算方法相比,本法与所研究物质的实际光谱参数较为接近,可为固定波长同步荧光光谱参数的理论计算提供一有效方法。     

Untersuchungen zurFriedel-Crafts-Reaktion. XVI. Darstellung isomerer 2-Acyl- und 3-Acyl-4-methoxyphenole

Acylation of 4-methoxy phenol according toFriedel andCrafts, as well as the rearrangement of its esters according toFries lead always to 2-acyl-4-methoxy phenols or to their demethylated compounds. The unknown 3-acyl-4-methoxy phenols were prepared in two steps: First, the ester is acylated with the corresponding acyl chloride and SnCl₄ in nitromethane. In the second step the resulting ketoesters are hydrolysed. This is a general method. The yields ofmeta-acylphenols are between 40 and 90%. The isomeric 2-acyl-4-methoxy-phenols which were partly unknown or accessible only in low yields have also been prepared for comparative spectral studies (UV, IR, NMR, MS) ofortho- andmeta-acylphenols.

     

Eu<Superscript>3+</Superscript>-fluorescence properties in nano-crystallized SnO<Subscript>2</Subscript>-SiO<Subscript>2</Subscript> glass-ceramics

Fluorescence and spectral hole burning properties of Eu³⁺ ions were studied in nanocrystals-precipitated SnO₂-SiO₂ glasses. The glasses were prepared to contain various amount of Eu₂O₃ using the sol-gel method, in which SnO₂ nanocrystals were precipitated by heating in air. In the glasses containing Eu₂O₃ less than 1%, the Eu³⁺ ions were preferentially doped in the SnO₂ nanocrystals and their fluorescence intensities were enhanced by the energy transfer due to the recombination of electrons and holes excited in SnO₂ crystals. The SnO₂ nanocrystals-precipitated glasses exhibited the persistent spectral holes with the depth of ∼25% of the total fluorescence intensities of the Eu³⁺ ions. With the increasing Eu₂O₃ concentration, the amount of SnO₂ nanocrystals decreased and the Sn⁴⁺ ions formed the random glass structure together with the silica network. This structure change induced the fluorescence intensities and the hole depth to decrease.