近场激光热透镜光谱分析法测定铌

采用氦-氖激光器(632．8nm)观测了铌(V)与2-(5-溴-2-吡啶偶氮)-5-二乙氨基苯酚(5-Br-PADAP)和酒石酸所形成的紫蓝色三元配合物的激光热透镜效应，建立了近场激光热透镜光谱分析法测定铌的新方法。铌(V)质量浓度在0-500ng/mL范围内与热透镜信号强度呈良好的线性关系，检出限为5ng/mL。该方法已应用于钢样及铌矿样中铌的测定。     

脉冲激光热透镜光度法的研究Ⅰ.钕的测定

本文采用探测激光非聚焦型光学结构,用自装的热透镜实验装置,研究了溶液中Nd~(3+)的热透镜行为和影响热透镜效应的一些因素。用热透镜光度法直接分析了混合轻稀土氧化物样品中钕的含量。大量共存的镧、铈、镨不干扰测定。用1.8mJ/脉冲的加热激光能量,检出限为3.2×10~(-5)吸光度。     

微量铂的2-(3,5-二氯-2-吡啶偶氮)-5-二甲氨基苯胺激光热透镜光谱法测定

基于2－（3，5－二氯－2－吡啶偶氮）－5－二甲氨基苯胺（3，5－diCl-PADMA)与铂的显色反应，以激光热透镜光主普法测定了微量铂；实验表明，在强酸性介质中，Pt(Ⅳ）与3，5－diCl-PADMA显色形成稳定的蓝色络合物，络合物最大吸收波长位于634nm处，与所用激光器输出激光波长λ652nm匹配较好，从而建立了激光热透镜光谱法测定铂的方法；铂质量浓度分别在0.005-0.04mg/L和0.025-0.4mg/L范围内与激光热透镜信号强度呈线性关系，方法灵敏度高，选择性、重现性好，用于样品测定，结果令人满意。     

强脉冲激光激发的热透镜光度分析法

用自装的热透镜测量装置,观察了强脉冲激光作用下的热透镜行为。测量丙酮/水混合液中的Cocl₂,检测限为3×10^-7M,相当于6×10^-6的吸光度。将差分放大技术用于热透镜测量,降低了He-Ne激光振幅噪声的影响,改善了信噪比。     

激光热透镜光谱分析法同时测定铜、钴和镍研究

基于2-(5-NO2-吡啶-2-偶氮)-1-羟基-8-氨基萘-3，6-二磺酸与铜(Ⅱ)、钴(Ⅱ)和镍(Ⅱ)反应酸度的差异及热透镜信号强度的加和性，建立了激光热透镜光谱法同时测定铜、钴和镍的新方法。测定铜、钴和镍的线性范围依次为0～200ng/mL、0～200ng/mL和0～100ng/mL，检出限依次为2ng/mL，2．5ng/mL和1ng/mL。方法已用于合成样品及人发样中铜、钴和镍的同时测定。     

2-（5-溴-2-吡啶偶氮）-5-二甲氨基苯胺激光热透镜光谱法测定痕量铑的研究

基于铑(Ⅲ)与2-(5-溴-2-吡啶偶氮)-5-二甲氨基苯胺(5-Br-PADMA)的高灵敏显色反应,建立了激光热透镜光谱法测定痕量铑的新方法。实验表明,在pH 3.6～6.0的HAc-NaAc缓冲介质中,Rh(Ⅲ)与5-Br-PADMA显色形成紫红色铑络合物;继续以1.2 mol/L HClO4酸化后,可转变为另一种具有较高吸收特性的绿蓝色质子化型体,其最大吸收波长位于612 nm处,与所用He-Ne激光器的输出激光波长(632.8 nm)能较好匹配。铑的质量浓度在5～140μg/L范围内与热透镜信号强度呈良好的线性关系,检出限(S/N=3)为1.1μg/L。该方法灵敏度高、选择性好,用于铑炭催化剂中痕量铑的测定,结果满意。     

催化近场激光热透镜光谱法测定痕量铱

将近场激光热透镜光谱分析法与动力学分析法相结合.基于铱(Ⅳ)催化高碘酸钾氧化耐尔蓝A的动力学反心,建立了催化近场激光热透镜光谱法测定痕量铱的新方法,并探讨了反应机理。结果表明:铱浓度在0.05～2.4μg/L范围内呈线性关系;俭出限为6.2 x 10-12g/mL。应用该方法测定矿样中痕量铱.结果满意。     

光敏分离薄膜激光热透镜光谱法测定微区痕量汞的研究

本文报道光敏分离薄膜激光热透镜光谱法测定微区痕量汞的研究。讨论了汞－双硫腙体系的光敏特性，及其光敏薄膜激光热透镜的产生机理，研究了不同溶剂介质对光敏分离薄膜热透镜信号的影响，采用光敏分离成功地进行了痕量汞的分离测定。     

2-(5-溴-2-吡啶偶氮)-5-二甲氨基苯胺激光热透镜光谱法测定微量钯

基于2-(5-溴-2-吡啶偶氮)-5-二甲氨基苯胺(5-Br-PADMA)与钯(II)的高选择性显色反应,建立了激光热透镜光谱法测定微量钯的新方法。在0.6 mol/L HClO4介质中,于室温下放置10 min,Pd(II)与5-Br-PADMA反应形成稳定的青蓝色配合物,其最大吸收波长位于611 nm处,与所用He-Ne激光器输出波长632.8 nm能较好匹配。钯质量浓度在5~150 ng/mL范围内与激光热透镜信号强度呈线性关系,检出限为1.6 ng/mL,以工作曲线的斜率计算,灵敏度较光度法提高115倍。常见金属离子及10倍量的铂、铑、铱、钌、锇和金等贵金属离子不干扰钯的测定,方法具有良好的选择性。本法应用于催化剂、矿石和合金中钯的测定。     

分光光度法与激光热透镜光谱分析法测定高散射物质光吸收的比较

通过理论和实验比较了分光光度法与激光热透镜光谱分析法在高散射背景下测量物质光吸收的差异。研究了在不同含量纳米TiO2的散射背景下，散射对分光光度法和热透镜光谱分析法测定耐尔蓝溶液含量的影响。结果表明，分光光度法对具有光散射性质试样的测定存在较大误差，而激光热透镜光谱分析法能较好的避免散射影响，测定结果准确。实验结果与理论分析相一致。     

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.     

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).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.