一种新型罗丹明B硫酰肼衍生物荧光探针的合成及对汞(Ⅱ)的检测应用

设计合成了一种可逆的Hg2+荧光增强型分子探针3’,6’-双(二乙氨基)-2-((4-氟基苯亚甲基)氨基)螺[异吲哚-1,9’-氧杂蒽]-3-硫酮,利用红外光谱、元素分析、核磁等方法对探针结构进行了表征。探针溶液本身荧光很弱,与Hg2+结合后荧光显著增强,由此建立了Hg2+测定的新方法。检测的适宜条件为:反应体系pH 4.5,反应时间25 min。本方法具有易于操作、灵敏度高、选择性好、线性范围宽和线性关系良好等优点,Hg2+浓度在0.001～0.20 mg/L范围内线性相关系数为0.9997,检出限为3.88×10"4mg/L。本方法对河水及土壤样品进行Hg2+加标回收实验,标准回收率分别为102.22%和94.24%。本方法对水质-汞环境标准样品(编号:GSBZ 50016-90,批号:202030)的测定结果为6.16μg/L,与标准值基本吻合。     

新的吲哚类同型二聚体荧光探针测定蛋白质的分析研究

采用新的水溶性吲哚类同型二聚体探针Ⅰ,建立了一种新的蛋白质荧光分析体系.在酸性条件下,蛋白质分子能与吲哚探针发生结合作用,体系荧光明显增强并向长波方向发生红移,荧光强度与蛋白质质量浓度呈良好的线性关系,在最优条件下,牛血清白蛋白BSA的线性响应范围0.80～25.00 μg/mL,检出限(3σ/K)为0. μg/mL;用于模拟样品的测定,1.00,2.00和5.00 μg/mL的样品测定回收率为99.0%～102.0%,相对标准偏差1.8%～2.8%;与国家标准方法比较,结果测定偏差为1.0%～4.1%.     

巯基棉分离富集-荧光分析法测定水中痕量汞

实验发现,在pH 7.8的KH_2PO_4-NaOH缓冲介质中,十二烷基硫酸钠(SDS)可使Hg(Ⅱ)与吖啶橙(AO)反应后的荧光明显增强,据此建立了测定汞的荧光分析新方法。在最佳实验条件下,其质量浓度线性范围为0～200μg／L,检出限为2.47×10~(-9)g／mL。新建方法通过巯基棉分离富集汞,用于环境水样中痕量汞的测定,相对标准偏差为2.1％～4.7％,样品加标回收率为99.3％～101.2％,结果满意。     

汞(Ⅱ)-邻菲啰啉-水杨基荧光酮荧光猝灭体系的研究及应用

在pH 8.0～9.0的KH2PO4-Na2B4O7缓冲溶液中,在乳化剂OP存在下,溶液中的汞(Ⅱ)与邻菲啰啉(o-phen)和水杨基荧光酮(SAF)反应生成一多元配合物,使水杨基荧光酮溶液的荧光猝灭,据此建立了测定痕量汞的荧光分析法.体系的激发波长λex=365.0 nm,发射波长λem=580 nm.汞的浓度在0～80μg/L范围内与△F存在良好的线性关系.方法的检出限为1.04 ng/mL.对1μgHg(Ⅱ)进行11次平行测定,其相对标准偏差RSD=1.9%,配合物的组成比为Hg(Ⅱ)o-phenSAF=122.方法用于环境水样中痕量汞的测定.     

汞(Ⅱ)-吖啶橙-十二烷基苯磺酸钠荧光体系的研究及应用

在pH7.0~8.0的KH2PO4-NaOH缓冲溶液中,溶液中的汞(Ⅱ)与吖啶橙(AO)、十二烷基苯磺酸钠(DBS)反应生成多元配合物,使吖啶橙溶液的荧光明显增强,据此建立了测定痕量汞的荧光分析新方法。体系的激发波长λex=436nm,发射波长λem=550nm。汞的质量浓度在0~180μg/L范围内与ΔF存在良好的线性关系,方法的检出限为4.2ng/mL,对1μgHg(Ⅱ)进行11次平行测定,其相对标准偏差RSD=5.8%。方法用于人发、蔬菜和茶叶样品中痕量汞的测定。     

红景天苷的荧光光谱分析

建立了测定红景天苷的荧光光谱方法.选择了最佳荧光激发波长和发射波长,考察了乙醇浓度、温度、放置时间、pH值和共存离子对测定结果的影响.红景天苷的荧光光谱具有良好的稳定性,在最佳实验条件下,其荧光强度与浓度在0.04 -18.03 μg/L范围内呈良好的线性关系,相关系数为0.9996,检出限为0.019 μg/mL.红...     

基于罗丹明类衍生物荧光增强的水体中Hg^2＋检测

利用一种罗丹明衍生物荧光探针的开环效应检测Hg2＋.在pH 7.0的Tris-HCl缓冲液中,Hg2＋与荧光探针结合导致罗丹明类衍生物开环,溶液颜色由无色变成粉红色,并且发射强的荧光.荧光强度与Hg2＋浓度在20~200 ng/L范围内呈良好的线性关系,检出限为4 ng/mL.实验考察了荧光探针的选择性以及温度、pH、荧光试剂浓度和盐度对Hg2＋检测的影响.结果表明该方法具有反应试剂水溶性好、选择性好和可常温检测等优点.方法应用于自来水、河水和湖水等水体中Hg2＋的检测,获得较好的回收率.     

共振散射光谱分析法测定环境水样中痕量汞

在pH 9.5的NH3-NH4C l缓冲溶液中,汞(Ⅱ)与双硫腙可形成能稳定存在的螯合物微粒,显示出共振散射效应。该微粒体系的最强共振散射峰在560 nm处,汞(Ⅱ)的质量浓度在0.028~6.140μg/mL范围内,共振散射与△I之间存在良好的线性关系,回归方程为△I=76.786ρ+2.7,相关系数为0.999 8,检出限0.012μg/mL Hg。利用共振散射测量水样中微量汞(Ⅱ),方法简单、灵敏度高、结果满意。     

电化学冷蒸气发生-原子荧光光谱法测定人发中的痕量汞

采用自制的电化学流通池作为汞蒸气发生器,以玻碳为阴极材料,结合原子荧光光谱法,在断续流动条件下,建立了电化学冷蒸气发生法-原子荧光光谱联用技术(ECVG-AFS)对汞的分析方法.在优化的实验条件下,汞在0～5.0μg/L范围内荧光强度与浓度呈良好的线性关系,汞的检出限为1.2 ng/L.对1μg/L Hg测定的相对标准偏差为1.8%(n=11).可用于人发标准样品中汞的测定.     

异硫氰酸荧光素-牛血清蛋白-Pb~(2+)“开关”型荧光探针测定尿液中胰蛋白酶

本文研究了"开关"型异硫氰酸荧光素(FITC)-牛血清蛋白(BSA)-Pb2+荧光探针测定胰蛋白酶。实验发现,FITC-BSA探针在Pb2+和十二烷基苯磺酸钠(DBS)存在下,可以发出较强的荧光,此时体系处于"打开"状态。当在pH=7.8的Tris-HCl缓冲溶液中加入胰蛋白酶后,FITC-BSA-Pb2+发生荧光猝灭,探针被"关闭",并且胰蛋白酶的浓度在一定范围内与探针的荧光猝灭程度呈良好的线性关系。实验表明,胰蛋白酶浓度与体系荧光猝灭程度在2.4~24μg/mL间呈良好线性关系,相关系数r=0.9972,方法检出限(3σ/k)为0.80μg/mL。该方法应用于尿液中胰蛋白酶的检测,其相对标准偏差(RSD)≤3.0%,回收率范围为102.1%~106.0%。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).