核壳纳米晶二硒化镉/硫化镉的合成及荧光法测定溶菌酶

以3-巯基丙酸为修饰剂,水相合成了具有发光效率高,光稳定性强等优良特性的CdSe2／CdS核壳纳米晶,粒径约为4nm,并将其成功用于溶菌酶的测定。在pH7．4的Na2HPO4-NaH2PO4缓冲溶液中,以365nm激发,体系在642nm处的荧光强度与溶菌酶的浓度呈线性关系,线性响应范围为0．5～8．0mg／L和8.0～32mg／L;线性方程分别为△F=0．97 2．21C(mg/L)和△F=12．20 0．70C(mg／L);检出限为0．20mg／L。将该方法应用于样品的测定,结果令人满意。     

荧光光谱法测定水泥中硫酸根含量

0．1mol／LHCl—4．0mg／mL TX-100—0．05mol／LBaCl2溶液体系的荧光很弱,加入SO4^2-后形成的(BaSO4)。微粒在410nm、470nm处产生2个荧光峰,SO4^2-浓度在2．0～80μg／mL浓度范围内与F470呈线性关系．据此建立了一个测定水泥样品中硫酸根的简便灵敏的荧光光谱分析新方法,其相对偏差(RSD)在1．90%-3．9％之间,回收率在97．0％～102％之间．     

碲化镉纳米晶荧光猝灭法测定痕量铜(Ⅱ)

制备了水溶性的CdTe纳米晶。基于铜（Ⅱ）离子在pH=7,80的磷酸盐缓冲溶液中对该纳米晶的荧光具有较强的猝灭作用,建立了一种测定铜（Ⅱ）离子的新方法。在最佳条件下,体系的相对荧光强度（△F）与铜（Ⅱ）离子的浓度呈线性关系,线性范围为8．0～320．0μg／L,其线性回归方程为：△F=-8．18-0．14c（μg／L）;检出限为3．24μg／L。本方法用于实际样品中痕量铜的测定,结果令人满意。     

氧氟沙星在胶束体系中的荧光特性及应用

研究发现十二烷基硫酸钠胶束对氧氟沙星荧光有明显的增敏作用，据此建立了直接测定人体尿液中氧氟沙星的等波长差同步荧光光谱法（△λ=90nm）。经样品测定，其线性范围为0．12－3．6mg/L，检出限为0．12mg/L，回收率为92．2％－97．8％，相对标准偏差为1．2％－2．7％。     

N-邻羧基苯基-N-(2-氨己基)草酰胺荧光特性的研究及应用

研究了酸度、温度对不对称草酰胺：N-邻羧基苯基-N-（2-氨己基)草酰胺(OBZE)荧光特性的影响。测定了该试剂的荧光量子产率。在pH8．0～9．5的H3BO3-NaOH缓冲介质中，NO3^-能使OBZE荧光强度定量猝灭，据此建立了荧光猝灭法测定NO3^-的新体系。OBZE的激发波长为210nm，发射波长为395nm。荧光猝灭值与NO3^-在0．004～0．68mg／L呈范围内线性关系，方法的检出限为0．004mg／L。实验了多种干扰离子的影响，已用于水中硝酸根离子的测定。     

用紫外分光光度法及荧光光度法研究肾上腺素在不同pH条件下的稳定性

在pH7．45磷酸盐缓冲溶液和盐水组成的模拟生理介质中，用UV-分光光度法及荧光光度法研究了肾上腺素分子中电子对能量的传递方式及不同的pH条件对肾上腺素稳定性的影响。结果表明：在此条件下，肾上腺素的特征吸收峰位于278．0nm波长处；当激发光谱波长为279．0nm时，在314．0nm及616．0nm两波长处出现肾上腺素的荧光发射光谱峰。据此提出了测定肾上腺素的荧光光度法，其线性范围为1．80mg·L^-1以内，检出限（S／N=3）为2．70×10^-4mg·L^-1。试验发现：当溶液的pH值大于10时，肾上腺素被氧气氧化生成羰基化合物，致使其吸收峰发生红移及荧光峰的减弱或消失。     

HPLC法测定鸡精中谷氨酸钠的含量

以邻苯二甲醛与谷氨酸钠中的氨基进行柱前在线衍生化反应,采用C18色谱柱分离、荧光检测器（激发340nm,发射450nm）进行测定,建立了柱前衍生反相高效液相色谱测定鸡精中谷氨酸钠含量的方法。该方法相对标准偏差为0．69％,加标回收率为99．1％～101％,在0．10~50．0mg／L范围内,谷氨酸钠的峰面积和浓度之间的相关系数为0．9999,保留时间和峰面积的相对标准偏差分别为1．22％和0．71％,鸡精中谷氨酸钠定量下限为0．2μg／g。     

5,10,15-三苯基-20-吡啶基卟啉荧光猝灭法测定痕量铅

:试验制备了一种荧光试剂5,10,15-三苯基-20-吡啶基卟啉(TPPyP),该试剂激发光谱(λ_(ex))为420nm时,在650nm波长处有发射光谱(λ_(em))峰。当试剂与铅(Ⅱ)反应时产生荧光猝灭现象。提出了以此试剂为荧光探针测定痕量铅(Ⅱ)的荧光光度法。在邻苯二甲酸盐-盐酸缓冲溶液中,一定量的十六烷基三甲基溴化铵(CTMAB)存在下,通过测定样品溶液和空白溶液在发射波长650nm的荧光强度,计算得反应液荧光强度的降低程度△F;结果表明:△F值与铅(Ⅱ)的质量浓度在1.0×10~(-4)～1.5×10~(-3)mg·L~(-1)范围内呈线性关系,方法的检出限(3s/k)为4.0×10~(-5)mg·L~(-1)。此方法用于膨化食品中铅(Ⅱ)的测定,回收率在95.0%～107.0%之间,相对标准偏差(n=6)小于3%。     

检测痕量纳米金的纳米催化光度法

在EDTA—NaOH介质中,金纳米微粒对盐酸联氨还原硫酸铜生成铜微粒这一慢反应具有较强的催化作用．铜微粒在750nm处产生一个吸收峰．随着纳米金浓度的增大,750nm处的吸光强度线性增大．对于粒径为10、30、50nm的纳米金,其线性范围、回归方程、检出限分别为0．12～1．68、0．36～2．80、1．00～5．00nmol／L,△A750nm=0．3205CAu＋0．0076、△A750nm=0．2201CAu＋0．0056、△A750nm=0．1150CAu＋0．0066,0．05、0．20、0．50nmol／L Au．分别对0．50、1．00nmol／L纳米金（d=10nm）平行测定10次,求得其相对标准偏差分别为4．2％、3．5％．     

高效液相色谱柱后化学衍生法测定食品中的VB1及叶酸含量

研究柱后化学衍生荧光检测高效液相色谱分离测定食品中维生素B1和叶酸的方法。采用C18柱,以含有3．5％乙腈的pH5．0磷酸盐缓冲溶液(0．05mol／L)作为流动相反相分离。色谱流出液在柱后与0．4％的过二硫酸钾溶液在线汇合后流经—Teflon管化学反应器时,维生索B1和叶酸转化为强荧光产物,由荧光检测器测定。在最佳条件下,进样20μL,维生素B1和叶酸工作曲线的线性范围分别为0．21～4．2mg／L和0．10～2．0mg／L,峰面积的相对偏差均为2．0％,回收率及实际样品测定结果满意。     

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%.     

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.