罗丹明3GO荧光猝灭法测定微量亚硝酸根

1　引　　言亚硝酸根与芳胺或苯甲胺反应因生成致癌物质亚硝胺而引起广泛的关注。测定亚硝酸根的方法除经典的Ｇｒｉｅｓｓ法外还有分光光度法、荧光法、催化动力学法等 ,但利用罗丹明 3ＧＯ与亚硝酸根发生的荧光熄灭法测定亚硝酸根的方法尚未见报道。本研究发现 ,在盐酸介质中 ,亚硝酸根的加入使罗丹明 3ＧＯ荧光强度明显降低 ,其降低程度与亚硝酸根的加入量间存在着良好的线性关系 ,从而建立了用罗丹明 3ＧＯ荧光熄灭法测定亚硝酸根的新方法。方法操作简单 ,灵敏度高 ,重现性好 ,可直接测定水样中的亚硝酸根。2　实验部分2 .1　仪器和试剂…     

荧光反猝灭法测定药剂中卡托普利

建立荧光反猝灭法测定卡托普利(CAT)的体系。碘(I-3)与罗丹明B(RhB)缔合作用使罗丹明B荧光信号强度减弱直至荧光猝灭,而卡托普利可将I-3还原为I-,使体系荧光信号再现。在2~20μmol·L^-1范围内荧光强度再现值ΔF与卡托普利浓度有线性关系:ΔF=-8.438+10.774 c(r=0.9986),检出限为3.34×10^-9 mol·L^-1。方法用于药剂卡托普利含量测定,测定值与标示量一致,加标回收率在95.2%~102.3%之间。     

动力学荧光猝灭法测定痕量铜

研究了在稀盐酸介质中，铜（Ⅱ）催化过硫酸钾氧化磺化钾，生成的Ｉ＾－３与罗丹明６Ｇ生成缔合物而使罗丹明，６Ｇ荧光猝灭，建立了催化荧光法测定痕量铜的方法，线性范围为４－５４检出限为１．６μｇ／Ｌ。     

罗丹明6G荧光猝灭法测定痕量肝素

在pH 8.0的缓冲体系中,肝素使得罗丹明6G的荧光发生明显猝灭,罗丹明6G的荧光猝灭程度在一定范围内与肝素的浓度成正比,据此建立了荧光猝灭法测定痕量肝素的方法,并对体系的荧光猝灭机理进行了讨论。体系的激发波长为482 nm,发射波长为560 nm,线性范围为0.05~3.0 mg/L,检出限为6.1μg/L。方法已应用于肝素钠注射液中肝素含量的测定。     

荧光共振能量转移猝灭法测定加替沙星

在pH=7.00的Britton-Robinson (B-R)缓冲溶液,及十二烷基硫酸钠(SDS)介质中,吖啶橙(AO)-罗丹明 (RB)能够发生有效的能量转移,使RB荧光增强.加替沙星(Gatifloxacin, GTFX)的加入又使得RB的荧光猝灭,据此建立了测定加替沙星的新方法.将此方法用于加替沙星片剂和粉针剂的测定,结果满意.实验表明,该方法简单、快速、灵敏、准确.     

能量转移荧光猝灭法测定加替沙星

在λ_(ex)/λ_(em)=470/566 nm、BR缓冲溶液(pH=5.72)、十二烷基苯磺酸钠介质中,吖啶橙(AO)与罗丹明6G(R6G)间能发生有效的能量转移,使R6G的荧光强度显著增强;加替沙星的加入,使R6G的荧光发生猝灭.应用AO-R6G能量转移荧光猝灭法测定加替沙星含量,提高了测定的灵敏度和选择性.加替沙星的浓度在0.6～9.0 μmol·L~(-1)范围内与R6G荧光猝灭程度呈线性关系;方法检出限为0.52 μmol·L~(-1);平行6次测定样品相对标准偏差为0.62%～0.84%;回收率为90.0%～105%.常见金属离子及药物敷料对测定无干扰,不经分离直接用于药物中加替沙星的测定.     

罗丹明6G荧光猝灭法测定微量钌

关于钌的三元络合物荧光分析法报道较少,S.Jaya曾报道基于Ru-SCN^--罗丹明6G三元络合物体系分析钌的分光光度法,罗丹明6G(简称R)染料分子中苯环之间有附加的氧桥,分子结构牢固,吸收光能不易失去,故产生荧光,钌(Ⅲ)与硫氰酸根形成的络阴离子与R的阳离子形成离子缔合物Ru(SCN)₆R₃,使罗丹明6G荧光猝灭,其猝灭值随钌的含量而增高,据此现象拟定了测定钌的方法,灵敏度较分光光度法提高20倍。     

罗丹明6G荧光猝灭法测定中草药中微量铁

在H2SO4溶液中,Fe3 与过量KI反应后生成I3-阴离子,I3-与罗丹明6G形成离子缔合物,并使罗丹明6G发生荧光猝灭,据此建立了测定Fe3 的荧光猝灭分析方法。方法的线性范围为20~200μg/L,检出限为8.3μg/L,用于中草药中铁的测定。     

2,4-二羟基苯乙酮苯腙荧光猝灭法测定铜

1 引 言胺类试剂是一类理想的荧光分析试剂,用其测定Al3+、Ga3+、Zn3+已显示出其灵敏度高、选择性好的优点。现虽有腙试剂荧光法测铜的报道,但这些方法检出限多数都在1μg/L以上,尚未见2,4-二羟基苯乙酮苯腙在荧光分析中的应用报道。本文首次合成了2,4-二羟基苯乙酮苯腙,研究了该试剂与铜荧光猝灭反应的最佳条件,建立的分析方法的检出限为0.22μg/L。方法用于矿泉水中铜的测定,结果满意。     

荧光猝灭法测定痕量砷?

根据在稀盐酸介质中,碘酸钾可与As?发生氧化还原反应生成I2,I2与荧光试剂吡咯红Y作用,使其荧光猝灭,提出了一种新的测定痕量As?的荧光分析法.该方法的线性范围为24.0～248 μg/L,检出限为14.1 μg/L,方法用于自来水、尿液、血清及合成样中痕量As?的测定,均获得满意结果.     

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.     

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.     

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.     

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.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.     

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%).