磁效应—偏振—共振同步荧光法同时测定痕量Qu,蒽,Bei

偏振－同步荧光法能有效地抑制同步扫描过程中散射光总水平的影响，外加磁场效应能有效地抑制散射光的波动。二者结合起来用于同时测定Ｑｕ、蒽、Ｂｅｉ，Ｂｅｉ检测限改善近６７倍，该法相对标准偏差小于２．７％。     

氢化物发生—冷阱捕获—色谱分离—原子吸收法测定天然水中坤的形态

研究建立了氢化物发生－冷阱捕获－色谱分离－原子吸收方法测定天然水中四种主要砷形态，测试系统自行组装，色谱柱填料采用ＣｈｒｏｍｏｓｏｒｂＧＡＷ－ＤＭＣＳ（粒径０．３～０．４５ｍｍ），其上涂布３％ＯＶ－１０１。方法的检出限以砷计分别为：Ａｓ（Ｖ）０．５１ｎｇ，Ａｓ（Ⅲ）０．４３ｎｇ，ＭＭＡ０．３８ｎｇ，ＤＭＡ０．６７ｎｇ；１２ｎｇ砷标准偏差为Ａｓ（Ⅴ）４．２１％，Ａｓ（Ⅱ）３．５６％，ＭＭＡ３．２３％     

8—羟基喹啉—5—磺酸—溴化十六烷基三甲胺荧光光度法测定痕量铊

本文研究了８－羟基喹啉－５－磺酸与铊的荧光反应，在表面活性剂ＣＴＭＡＢ存在下，大大提高了反应的灵敏度，在０￣２．５μｇ／２５ｍｌ范围内Ｔｌ（Ⅲ）量与△Ｆ值呈良好的线性关系，检出下限为６．６４ｎｇ／ｍｌ，其相对标准偏差为２．３４％。本法采用聚氨酯泡沫塑料吸附铊后与其它干扰离子分离，可用于地质试样中铊的测定。     

一阶导数停流法测定药物和饮用水中的铁

本文利用Ｆｅ＾３＋离子催化Ｈ２Ｏ２氧化四甲基对苯二胺的反应，将采用停流技术获得的动力学曲线转换成一阶导数曲线，根据导数峰高值与Ｆｅ＾３＋离子浓度的线性关系测定药物和自来水中的含量，本方法的线性范围为４．０－４０．０ｎｇＦｅ＾３＋／ｍｌ，相对标准偏差小于２．５％，标准加入回收率在９８．７％－１０１％之间，检测限为１．９２ｎｇＦｅ＾３＋／ｍｌ。对照实验结果表明，导数动力学法比一般非导数动力学法具有线关     

反相高效液相色谱分离—安培法检测酚类化合物

本文报道了ＲＰ－ＨＰＬＣ－安培法检测测定酚类化合物的条件，在Ｓｈｉｍ－ｐａｃｋＣＬＣ－Ｃ８柱上用含０．５ｍｏｌ／Ｌ ＮａＨ２ＰＯ４缓冲溶液的５％甲醇水溶液洗脱分离，于Ｅ＋１．０Ｖ处检测，线性范围在０－７μｇ／ｍｌ，检测限达ｎｇ／ｍｌ。     

在线的离子交换预富集流动注射—原子吸收光谱法测定铁,锰,…

本文使用大孔弱酸阳离子交换树脂Ｄ－１５２微型柱预富集，将流动注射与原子吸收光谱法相结合测定了Ｆｅ，Ｍｎ，Ｃｕ和Ｃｄ等离子，讨论了溶液酸度，采样速率及洗脱剂等对上述四元素灵敏度的影响，在采样频率４０次／ｈ，采样体种７ｍｌ地Ｆｅ，Ｍｎ，Ｃｕ和Ｃｄ增敏１６－２４倍，检出限分别为０．９、０．４、０．４和０．１ｎｇ／ｍｌ     

偏振—导数—同步荧光法同时测定痕量芴,苊,蒽,北

本文采取偏振－导数－同步扫描联用技术同时测定痕量的芴、苊、恩和北多环芳烃。实验结果表明，多种荧光分析技术联用可以弥补单独应用其中一种或两种技术的不足，扬长避短，大大改善此类化合物的检测限。该方法同时测定上述四种组份，检测限依次为０．０８９、２．４、０．０４５、０．００９６ｎｇ／ｍＬ，相对标准偏差不大于５％。     

烟草中Fe,Co一阶导数分光光度法同时测定的研究

本文研究了在ｐＨ４．０时，ｍｅｓｏ－四（４－磺酸基苯基）卟啉与铁、钴同时络合显色的反应条件以及一阶导数光谱行为。此体系一阶导数的灵敏度比零阶导数灵敏度高。Ｆｅ￣（３＋）～０．１８μｇ／ｍＬ、Ｃｏ￣（２＋）０～０．２４μｇ／ｍｌ，范围内符合比耳定律；检测限为：Ｆｅ￣（３＋）＝０．４８ｎｇ／ｍＬ，Ｃｏ￣（２＋）＝０．２ｎｇ／ｍＬ。回收率为：Ｆｅ９８．５％～１００．８％，Ｃｏ９９．２％～１０１．３％。此方法用于烟草中痕量Ｆｅ、Ｃｏ测定，与ＡＡＳ值相比较，结果令人满意。     

钴（Ⅱ）—β—巯基丙酸—NaNO2体系的极谱化波研究

在ｐＨ３．８的Ｈ２ＳＯ４－ＮＨ４Ａｃ介质中，Ｃｏ（Ⅱ）－β－巯基丙酸（ＭＰＡ）－ＮａＮＯ２体系产生－灵敏的极谱催化波，峰电位在－０．８４Ｖ（ｖｓ．ＳＣＥ）钴浓度在０．０２～１００ｎｇ／ｍＬ范围内与峰电流呈线性关系，检出限为０．０１ｎｇ／ｍＬ。本文对极谱波的性质和机理进行了初步探讨，本法用于土壤中总钴和有效钴的测定，结果满意。     

铬（Ⅵ）—8—氨基喹啉—5—偶氮—对苯磺酸钠的极谱行为

Ｃｒ（Ⅵ）在ＮＨ４ＯＨ－ＮＨ４Ｃｌ－ＮａＮＯ２－８－氨基喹啉－５－偶氮－对苯磺酸钠体系中产生一灵敏的阴极极化二次导数催化波，其峰电位在－１．３３Ｖ（ｖｓ．ＳＣＥ）。Ｃｒ（Ⅵ）在０．４０￣１２．０ｎｇ／ｍｌ范围内与峰电流成正比。本法已用于为水中Ｃｒ（Ⅵ）的测定，结果良好。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.     

Studies of Photoionization of CF3 I by Femtosecond Time-resolved Mass Spectrometry

The multi-photon dissociative photoionization dynamics of CF3I has been studied with femtosecond two-color pump-probe time of flight mass spectra at a pump pulse of 265 nm and a probe pulse of 398 nm. The life constants of CF3I+ and its fragment ions CF3+ and I+ are obtained as (96±7), (198±130) and (167±6)fs, respectively. The multi-photon dynamics leading to these ions differ. CF3I+ corresponds to a (1+2′) transition with one-photon pump excitation to the A band of CF3I. CF3+ are mainly formed by a tow-photon probe excitation to the CF3+ with subsequent dissociation of parent ions. I+ are produced in (2+2′) combined with (1+1′+2′) process. The results provide information on the multi-photon pathways involved.