鲱鱼精DNA修饰纳米金催化Fehling反应——共振散射光谱法检测痕量Hg2＋

用鲱鱼精DNA (hsDNA)修饰10 nm的纳米金制备了Hg^2＋的hsDNA修饰纳米金共振散射光谱探针(AuhsDNA). 在pH 7.0 Tris-HCl缓冲溶液中及0.017 mol/L NaCl存在下, Hg^2＋与AuhsDNA形成稳定的Hg^2＋-DNA结合物, 引起AuhsDNA中的纳米金析出并聚集形成纳米金簇. 该溶液用150 nm滤膜过滤后, 滤液中过量的AuhsDNA可催化Fehling试剂-葡萄糖反应生成氧化亚铜微粒, 该微粒在580 nm处有一个较强的共振散射峰. 随着汞离子浓度增大, 形成的纳米金簇越多, 滤液中AuhsDNA越少, 生成的氧化亚铜微粒减少, 580 nm处氧化亚铜微粒的共振散射光强度线性降低, 其共振散射光强度降低值?I₅₈₀ nm与汞离子浓度在1～833 nmol/L范围内成线性, 回归方程、相关系数、检出限分别为 ?I_{580 nm}＋0.9, 0.9990, 0.3 nmol/L Hg^2＋. 该法用于废水中Hg^2＋的检测.     

二氧化锰纳米颗粒调控的紫外可见吸收-荧光双通道传感器的构建及D-青霉胺的检测

以聚乙烯亚胺(PEI)同时作为模板和还原剂,基于原位氧化还原反应,一步法制备二氧化锰纳米颗粒(MnO₂ NPs),并对其形貌、组成、紫外可见吸收、催化氧化特性进行了表征。结果表明,MnO₂ NPs能够催化氧化邻苯二胺(OPD)为2,3-二氨基吩嗪(DAP),产生420 nm处的紫外可见吸收和560 nm处的荧光发射。D-青霉胺(DPA)中的活性巯基可与MnO₂发生特异性反应,还原降解催化剂,抑制其催化氧化活性,使得体系紫外可见吸收-荧光信号减弱甚至消失。基于DPA浓度与体系光谱信号变化的关系,我们建立了MnO₂ NPs介导的紫外可见吸收-荧光双通道传感DPA的新方法。荧光传感通道具有更好的线性范围和灵敏度,该方法线性范围为1~80 μmol·L^-1,检出限为0.54 μmol·L^-1。此外,MnO₂ NPs介导的荧光传感DPA应用于人体尿液样品分析中的回收率为98.31%~107.76%,证明了该方法的可靠性。     

超细钴纳米粒子催化1-己烯低压氢甲酰化反应的原位红外光谱研究

利用原位透射红外光谱研究了2.8 nm超细钴纳米粒子在2~3 MPa合成气(CO:H₂ = 1:1)和100 ^oC条件下催化的1-己烯氢甲酰化反应. 结果表明, 在反应中出现与Co₂(CO)₈类似的红外吸收峰(2071, 2041和2022 cm^-1), 被证明是不同Co位点端式吸附CO. 首次观测到了位于2054 cm^-1处吸收峰处的物种, 可能归属为RCH₂CH₂COCo. 通过此中间物种,产物醛可以在钴催化剂表面经由结合一个氢原子脱除反应而获得.     

一种高灵敏度高选择性的荧光素基比色荧光锌传感器

本文报道了一种基于荧光素的锌离子传感器FN1,其在甲醇溶液中显示了对锌离子极高的灵敏度和选择性。随着锌离子的滴加,紫外-可见光谱中最初在371 nm处的吸收峰消失,在437 nm处出现了一个新峰。当在混合金属离子的甲醇溶液中滴加了相对于二价金属离子的等物质的量浓度的锌离子或相对于一价金属离子0.5倍物质的量浓度的锌离子后,锌离子积分荧光强度增强了近37倍（Φ=0.48,λ_max(em)=513 nm）,估算的锌离子检测限为7 μg·L^-1。基于紫外-可见光、荧光和质谱的结果,讨论了1∶1的FN1/Zn²⁺配合物的结合机理。     

二氧化锰纳米颗粒调控的紫外可见吸收-荧光双通道传感器的构建及D-青霉胺的检测

以聚乙烯亚胺(PEI)同时作为模板和还原剂,基于原位氧化还原反应,一步法制备二氧化锰纳米颗粒(MnO₂ NPs),并对其形貌、组成、紫外可见吸收、催化氧化特性进行了表征。结果表明,MnO₂ NPs能够催化氧化邻苯二胺(OPD)为2,3-二氨基吩嗪(DAP),产生420 nm处的紫外可见吸收和560 nm处的荧光发射。D-青霉胺(DPA)中的活性巯基可与MnO₂发生特异性反应,还原降解催化剂,抑制其催化氧化活性,使得体系紫外可见吸收-荧光信号减弱甚至消失。基于DPA浓度与体系光谱信号变化的关系,我们建立了MnO₂ NPs介导的紫外可见吸收-荧光双通道传感DPA的新方法。荧光传感通道具有更好的线性范围和灵敏度,该方法线性范围为1~80 μmol·L^-1,检出限为0.54 μmol·L^-1。此外,MnO₂ NPs介导的荧光传感DPA应用于人体尿液样品分析中的回收率为98.31%~107.76%,证明了该方法的可靠性。     

核酸适体修饰纳米金共振散射光谱探针快速检测痕量Pb2＋

以柠檬酸三钠做稳定剂, 用硼氢化钠还原氯金酸制备了粒径为5 nm的纳米金. 用铅离子核酸适体aptamer保护纳米金获得了检测铅离子的适体纳米金(aptamer-NG)共振散射光谱探针. 在pH 7.0的Na₂HPO₄-NaH₂PO₄缓冲溶液中及30 mmol•L^－1 NaCl存在下, aptamer-NG稳定而不聚集. Pb^2＋可与该探针中的aptamer形成非常稳定的G-四分体结构, 并释放出纳米金. 在NaCl作用下纳米金聚集形成较大的微粒, 导致552 nm处共振散射峰强度增大. Pb^2＋浓度在0.07～42 nmol•L^－1范围内与552 nm处共振散射强度增大值ΔI成线性关系, 其回归方程为ΔI＝12.0c＋9.2, 线性相关系数为0.9965, 方法检出限为0.03 nmol•L^－1 Pb^2＋. 该方法用于水样中铅离子检测, 结果与石墨炉原子吸收光谱法结果一致.     

AgPd双金属纳米空心球的合成及其催化性能

以Ag纳米颗粒为牺牲模板,H₂PdCl₄为前驱体,抗坏血酸为还原剂,聚乙烯吡咯烷酮为表面活性剂,在70 ℃下采用电偶置换法结合还原法制备出AgPd双金属纳米空心球。采用紫外可见光谱、粉末X射线衍射、透射电镜结合能量色散等手段对由不同体积的0.01 mol·L^-1 H₂PdCl₄溶液制备的产物进行结构表征。结果表明,随着H₂PdCl₄溶液体积的增加,产物的空心化程度逐渐升高,晶粒的尺寸逐渐增大。当 H₂PdCl₄溶液体积为 120 μL时,合成的 AgPd双金属纳米空心球组成和结构较为均匀,其粒径约为 25 nm,壳层厚度 2~3 nm。双金属中,由于 Ag 和 Pd 电负性的差异,电子从 Ag 转移到了 Pd,使 Pd 表面出现电子富集区,显著提高了其催化效率。将所合成的AgPd双金属以及纯金属Ag和Pd作为催化剂,分别用于硼氢化钠催化还原4-硝基苯酚的反应,发现AgPd双金属的催化性能远高于纯金属Ag和Pd,其中AgPd-120纳米空心球(H₂PdCl₄溶液体积120 μL)作催化剂时的反应速率常数最高,是同等尺寸纯Ag纳米球的24.0倍,纯Pd纳米立方体的14.7倍。     

AgPd双金属纳米空心球的合成及其催化性能

以Ag纳米颗粒为牺牲模板,H₂PdCl₄为前驱体,抗坏血酸为还原剂,聚乙烯吡咯烷酮为表面活性剂,在70℃下采用电偶置换法结合还原法制备出AgPd双金属纳米空心球。采用紫外可见光谱、粉末X射线衍射、透射电镜结合能量色散等手段对由不同体积的0.01 mol·L^-1 H₂PdCl₄溶液制备的产物进行结构表征。结果表明,随着H₂PdCl₄溶液体积的增加,产物的空心化程度逐渐升高,晶粒的尺寸逐渐增大。当H₂PdCl₄溶液体积为120 μL时,合成的AgPd双金属纳米空心球组成和结构较为均匀,其粒径约为25 nm,壳层厚度2~3 nm。双金属中,由于Ag和Pd电负性的差异,电子从Ag转移到了Pd,使Pd表面出现电子富集区,显著提高了其催化效率。将所合成的AgPd双金属以及纯金属Ag和Pd作为催化剂,分别用于硼氢化钠催化还原4-硝基苯酚的反应,发现AgPd双金属的催化性能远高于纯金属Ag和Pd,其中AgPd-120纳米空心球(H₂PdCl₄溶液体积120 μL)作催化剂时的反应速率常数最高,是同等尺寸纯Ag纳米球的24.0倍,纯Pd纳米立方体的14.7倍。     

2,4,4'-三羟基脱氧安息香-3'-磺酸钴的合成、晶体结构表征及性质研究

合成了未见文献报道的水溶性很好的2,4,4'-三羟基脱氧安息香-3'-磺酸钴, 采用IR, UV, ¹H NMR和元素分析对其进行了表征, 并利用X射线单晶衍射仪测定了该化合物的晶体结构. 使用荧光光谱法检测了化合物对羟基自由基的清除作用, 紫外光谱法检测其对超氧自由基的清除作用. 实验结果表明, 2,4,4'-三羟基脱氧安息香-3'-磺酸钴[C₂₈H₄₆CoO₂₆S₂]属于单斜晶系, 空间群C2/c, a＝3.3937(3) nm, b＝0.85180(7) nm, c＝1.37455(11) nm, α＝90°, β＝97.8200(10)°, γ＝90°, Z＝4, V＝3.9365(5) nm³, D_c＝1.555 g/cm³, F(000)＝1924, R₁＝0.0329, wR₂＝0.0852, 具有较好的清除羟基自由基和超氧自由基的作用.     

Co3O4/ZnO修饰针灸针的制备及其在葡萄糖检测领域的应用

将Co₃O₄/ZnO针状纳米棒材料修饰到针灸针表面用于检测葡萄糖浓度的变化。首先采用水热法在针灸针表面得到Co（CO₃）_0.5（OH）·0.11H₂O针状纳米棒前驱体,然后在500 ℃条件下退火3 h得到Co₃O₄针状纳米棒阵列。再采用浸渍法将预制备好的ZnO量子点修饰到Co₃O₄针状纳米棒表面,得到Co₃O₄/ZnO复合修饰的针灸针。研究发现此针灸针对葡萄糖具有较好的电流响应（2 264.27 μA·L·mmol^-1·cm^-2）、较快的响应速度（<4 s）及较低的检测极限（0.311 μmol·L^-1（S/N=3））。且该针灸针在用于检测人体模拟细胞液中葡萄糖浓度时,对抗坏血酸和尿素等表现出较强的抗干扰性。     

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.