钐,铕—四环素类抗生素络合物荧光性能的研究及其在荧光分析中的应用

本文探讨了钐、铕－四环素、强力霉素、土霉素、金霉素络合物的荧光性能及利用该体体系以荧光分析光度法测定痕量钐和铕的可能性与最佳测定条件。结果表明：在高碱度条件下，以四环素体系的稳定性、灵敏性最好，钐和铕的检测限分别为３８．２和０．０９ｎｇ／ｍＬ。     

钐、铕-四环素类抗生素络合物荧光性能的研究及其在荧光分析中的应用

本文探讨了钐、铕-四环素、强力霉素、土霉素、金霉素络合物的荧光性能及利用该体系以荧光分析光度法测定痕量钐和铕的可能性与最佳测定条件.结果表明:在高碱度条件下(pH12～1.0mol/L NaOH),以四环素体系的稳定性、灵敏性最好,钐和铕的检测限分别为38.2和0.09ng/mL.     

四环素-Ca2+-CTMAB三元配合物体系荧光光谱的研究与应用

研究了Ca2+和阳离子表面活性剂CTMAB对四环素(TC)的荧光增敏作用,提出了一种利用Ca2+-TC-CTMAB三元配合物协同增敏体系来测定TC含量的新方法.在Ca2+-CTMAB及TC共存体系中,由于三元配合物的生成使TC的荧光强度急剧增加,其荧光强度与TC浓度在8.0×109-9～1.0×10-5 mol/L范围内具有良好的线性关系,方法检出限为5.97×10-9 mol/L.该法用于TC片剂、尿液及牛奶中残留TC的测定,加标回收率为82.4%～98.3%.同时对TC在不同介质中的荧光增敏作用机理进行了初步探讨.     

TTA-phen-吐温80胶束增溶体系荧光分析法测定痕量钐和铕

2-噻吩甲酰三氟丙酮(TTA)和诸如三正辛基氧化膦(TOPO)、邻菲罗啉(phen)等中性附加配位体所组成的协同萃取体系已应用于荧光分析法测定钐和铕,该体系选择性、灵敏度均颇高,适用于岩石、矿物、生物体的分析,但需使用有机溶剂。竹田津等将非离子表面活性剂用于荧光分析,免去了有机溶剂萃取操作,方法简便,如:TTA-TOPO-TritonX-100体系荧光法测定钐、铕,PTA(三氟乙酰特戊酰甲烷)-TOPO-BL-9EX体系荧光法测定钐、铕、铽等。本文使用phen代替TOPO,以非离子表面活性剂吐温80为增溶剂,研究了TTA-phen-吐温80体系荧光法测定钐和铕的最佳条件、干扰离子影响及回收率,均取得较为满意的结果。     

吡啶—2,6—二羧酸体系导数荧光法同时测定铀,钐,铕,铽,镝

本研究了吡啶－２，６－二羧酸（ＤＰＡ）体系导数荧光法同时测定铀，钐，铕，铽，镝的最佳条件。在ｐＨ５．５，４．８×１０＾－＾５ｍｏｌ／ＬＤＰＡ，激发波长２７２ｎｍ的条件下，可分别在５１８，６３９，６２１，５３９和６６ｎｍ处测定铀，钐，铕，铽和镝，检测限分别达到７，０．４，０．００４，０．０２６和０．２５ｎｇ／ｍＬ。应用本法测定了混合成试液中上术五种离子含量，回收率为９２．３－１０８．１％。     

胶束增敏法测定盐酸左氧氟沙星的研究

研究了盐酸左氧氟沙星（OFLX）在胶束体系中的荧光性质，发现十二烷基硫酸钠对OFLX有较强的增敏作用，据此建立了胶束增敏荧光光谱法测定痕量OFLX的新方法。其线性范围为0～1．00μg/mL，检出限为4．73ng／mL。     

稀土元素共发光效应的研究——铕、钐、镓-二苯甲酰甲烷-十六烷基三甲基溴化铵-Triton X-100体系的共发光效应及其应用

1 引 言 稀土元素共发光效应的研究已有许多报道,其研究体系主要集中于钐、铕-β-二酮荧光体系,β-二酮中以噻吩甲酰三氟丙酮研究得最为详尽,协同配体大多采用三辛基氧化膦,邻菲咯啉等。本文研究了钐、铕-二苯甲酰甲烷(DBM)荧光体系,在表面活性剂十六烷基三甲基溴化铵(CTMAB)及Triton X-100存在下,形成钐或铕-DBM-CTMAB三元离子缔合络合物。当于上述体系中加入Gd~(3+)后,荧光强度大大增加,约比无Gd存在时提高50倍.并用多点增量法同时测定了稀土氧化物中痕量的钐和铕,结果令人满意。     

TTA-TOPO萃取荧光分析法测定岩矿及环境试样中的痕量钐和铕

作者等曾考察了钐、铕和噻吩甲酰三氟丙酮(TTA)与三正辛基膦化氧(TOPO)所形成的三元络合物的荧光特性,并应用于测定稀土矿物中的钐、铕。本文将此法应用于测定岩矿及环境试样中的钐和铕,结果较为满意。 1.主要试剂和仪器: (1)1ppm钐和0.1ppm铕标准溶液(0.1N盐酸)。 (2)1×10~(-4)MTTA-2×10~(-2)MTOPO己烷溶液。 (3)O.2MTTA苯溶液。     

左旋氧氟沙星的荧光光谱法研究

提出了一种测定左旋氧氟沙星（LEV）的荧光光谱新方法。该法基于电子受体氯冉酸（CL）和2,3-二氰-5,6-二氯-1,4-对苯醌（DDQ）与电子给体左旋氧氟沙星之间的荷移反应,显示这两种受体能强烈增敏LEV的荧光强度。对影响反应的不同变量和参数进行了研究,建立了两种荧光光谱法测定LEV的新体系：（1）CL体系,线性范围为0．06～3．6μg／mL,检出限为0．02μg／mL;（2）DDQ体系,线性范围为0．12～2．2μg／mL,检出限为0．04μg／mL。所提方法已用于制剂中左旋氧氟沙星含量的测定,回收率分别为99．72％～99．36％和99．36％～98．86％。     

TTA-Phen-吐温20胶束体系荧光分析法测定地质试样中的痕量钐和铕

本文研究了2-噻吩甲酰三氟丙酮(TTA)-邻菲绕啉(Phen)-吐温20胶束体系荧光法测定钐、铕时钙离子的熄灭效应和草酸钙共沉淀法的最佳条件。方法已用于水系沉积岩和塘积物等地质试样中痕量钐、铕的测定并得到满意的结果。     

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.