有机溶剂对镧和钇ICP光谱信号的增敏机理研究

本文考察了有机溶剂（乙酸丁酯）及有机试剂（PMBP）引入ICP－AES对稀土元素镧和钇光谱信号的影响。实验结果表明，有机溶剂的引入明显增大了待测物的传质效率，从而导致分析灵敏度的改善。与水相相比，有机相的引入对ICP激发温度未产生明显影响，但使线对强度比（LogI^ /I)增强，有利于待测物的电离。     

Self aggregation of binary mixtures of sodium dodecyl sulfate and polyoxyethylene alkyl ethers in aqueous solution

The mixed micelles of sodium dodecyl sulphate (SDS) with Brij35 and Brij 97 were studied separately by fluorescence measurement using pyrene as fluorescent probe. In the range of 0–1.0 mole fraction (X) of added SDS to Brij solutions, the cmc value of the mixed micelles varies from 0.085 to 8 mmol with Brij 35 and 0.04 to 8 mmol with Brij 97. The aggregation number also changes. A measure of the stability of mixed micelles is also presented. The interaction parameter ₁₂ and the chain–chain contribution parameter (B₁) are extracted from the analysis of the results. This parameter B₁ is related to the standard free energy change associated with the introduction of one ionic species into a nonionic micelle coupled with the release of one nonionic species from the micelle. The clouding behaviour of Brij 97 in the presence of SDS was investigated and the associated thermodynamic parameters of clouding were generated and discussed.     

Syntheses of per-N labeled etioporphyrins I-IV and a related tetrahydrobenzoporphyrin for applications in organic geochemistry and vibrational spectroscopy

Nitrogen-15 labeled pyrroles have been prepared from commercially available ¹⁵N glycine or sodium nitrite using the Barton-Zard, Knorr, and Kleinspehn approaches. These pyrroles were used as intermediates in the synthesis of per-¹⁵N labeled porphyrins needed for the analysis and assignment of vibrational spectra for sedimentary porphyrins. Etioporphyrin-I was prepared via pyrromethene intermediates, while etioporphyrins II-V and a related tetrahydrobenzoporphyrin were synthesized via stepwise routes involving the copper(II) mediated cyclization of a,c-biladienes as the key step. Detailed analyses of both the proton and carbon-13 NMR spectra provide nitrogen-15 coupling constants for these important structures.     

Spin-transition behaviour of transition metal complexes with 2,6-bis-(benzimidazol-2′-yl)-pyridine induced by deprotonation of the complex

Summary 2,6-bis-(Benzimidazol-2-yl)-pyridine (bzimpy = H₂ L) acts as a bidentate ligand when combining with transition metal ions. The complexes [M(bzimpy)₂](ClO₄)₂ (M = Fe²⁺, Mn²⁺, Zn²⁺, Co²⁺, and Ni²⁺) were obtained as solids. The protonation constants (logK) for the ligand and the complexes were evaluated in 30:70 (v/v) H₂O:EtOH at 293 K and at constant ionic strength of 0.12M KCl. Coordination of the ligand to the metal ions leads to an increase of acidity of the imino-hydrogen of the benzimidazole group of the ligand as a function of the complex stability. Deprotonation leads to a spin-state transition (intermediate spin-state low-spin) of the iron(II)-complex, followed by a shift of the metal-to-ligandcharge transfer band (MLCT) to lower energies (_max=563 to 580 nm). The d-d absorption bands are found to shift to higher energies and the low-spin isomer is favoured at room temperature. An opposite shift of theMLCT band (_max=563 to 557 nm) is observed when HClO₄ is added to the complex solution, rendering the high-spin state of the complex more favourable.On leave from the Chemistry Department, Jahangirnagar University, Dhaka, Bangladesh     

LaC_3~n(n=-1,0,+1)分子簇的理论研究(英文)

用密度泛函方法研究了ＬａＣ３ｎ（ｎ＝－１，０，＋１）分子簇的结构和稳定性，对这个四原子体系，提出了５种可能构型，其中３种具有Ｃ２ｖ对称性，２种为Ｃ∞ｖ对称性．在Ｃ２ｖ对称性结构中，其中１个为Ｌａ接在弯曲的Ｃ３链上，第２个是Ｌａ通过２个键与Ｃ３环相链，第３个是Ｌａ通过１个键与Ｃ３环相连；在Ｃ∞ｖ对称性中，第１个Ｌａ接在Ｃ３链的一端，而在第２个构型中，Ｌａ被插入在Ｃ３链中．结果表明，环状结构当Ｌａ接在弯曲的Ｃ３链上的是局域极小值并且最稳定     

亮氨酸与异亮氨酸在金/银核-壳复合纳米粒子上的吸附状态

The Raman spectra and Surface enhanced Raman spectra (SERS) of leucine and isoleucine adsorbed on core-shell Au/Ag nanoparticles were obtained and assigned, and the different Raman peaks resulting from different vibrational models of the isomers忆groups were analysed. In Raman spectra, the leucine’s (ω(CH3)) is at 962, 945, 924 cm-1, (δas(CH3)) at 1408, 1454 cm-1; corresponding values for isoleucine are, 922 cm-1 and 1448, 1420, 1394 cm-1, respectwely. The difference in the peak positions of corresponding groups between leucine and isoleucine is more apparent in the SERS at acidic and basic conditions. The relationship between leucine and isoleucine’s concentration and SERS was interpreted preliminarily and the adsorption model on the core-shell Au/Ag nanoparticle surface was speculated.     

Analysis by liquid chromatography‐tandem mass spectrometry of biophenolic compounds in virgin olive oil,Part II

In this study the qualitative and quantitative content of the biophenolics in virgin olive oils is evaluated by liquid chromatography‐tandem mass spectrometry. The extraction and purification method for these compounds from virgin oils was optimised. After liquid‐liquid and solid‐phase extraction the separation of 35 of these compounds was achieved on reversed phase in gradient mode. The detection was preliminarily by UV and fluorescence, but then the final choice was ion‐spray tandem mass spectrometry in multiple reaction monitoring mode in negative ionization, acquiring two diagnostic product ions from the chosen precursor [M—H]^–. Using this last approach we obtained the best sensitivity, selectivity, and specificity. The recovery of the method ranged from 70–90% and detection limits were less than 1 ng for all the analyzed compounds.     

LiCl对Fe_2O_3/SiO_2甲烷氧化偶联反应的助催化作用

使用穆斯堡尔谱，ESR和XRD等技术表征了未添加助剂和添加LiCl的Fe2O3／SiO2催化剂．XRD结果指出，添加LiCl的Fe2O／SiO2催化剂出现铁酸盐和α-方石英的衍射峰，这种结果的出现与该催化剂有较高的C2烃选择性密切相关。穆斯堡尔谱结果表明：添加LiCl的Fe2O3／SiO2催化剂有更高的结构对称性．这种结构对分子氧的活化起着重要的作用．氯的存在大大降低了氧的离解吸附的速率，减少了原子氧的吸附位的数目，并可除去吸附的原子氧，该氧种对COx的生成有利．     

PHOTOCATALYTIC HYDROGEN EVOLUTION FROM WATER SPLITTING UNDER VISIBLE LIGHT IRRADIATION ON NOVEL PHOTOCATALYST FULLENES-PVP-ZN0.999NI0.001S

Fullerenes (C60/C70) linked up to Ni-doped ZnS through the medium of an amphalic polymer polyvinyl pyrrolidone (PVP) to form a new kind of photocatalyst for hydrogen evolution from aqueous Na2S/Na2SO3 solution under visible light irradiation, the photocatalytic activities of this novel photocatalyst C60/C70-PVP-Zn0.999Ni0.001S are 3-5 fold higher compared with that of precurse catalyst Zn0.999Ni0.001S. This result could be attributed to Schottky barrier layer built between C60/C70 and Zn0.999Ni0.001S due to the electro-negativity of C60 and characteristic of being used as a multiple electron acceptor. C60 or C60/C70, its moiety, with its low energy first excited singlet state, is a good energy acceptor and in addition readily accepts multiple electrons, making it a potential electron accumulate as we know, which could protect the separation between electrons and holes against combination. This is an important reason for the marked increase of amount of H2 evolution during the photocatalytic process for the composite system C60/C70-PVP-Zn0.999Ni0.001S.     

反相毛细管电色谱中中性化合物的保留及有机改性剂对其保留值的影响

以硫脲作为电渗流标记物测定的死时间和以苯同系物线性回归方法测定的死时间为基础，将液相色谱中溶质保留值方程应用到电色谱中，得到了容量因子与二元流动相体系中有机改性剂含量之间的关系曲线；通过实验数据说明了一些极性的电中性化合物在电场作用下也会发生迁移而引起保留值的变化，且这种变化还受有机改性剂含量的影响。