纳米级氧化铅粉体的合成

采用均匀沉淀法合成碳酸铅,在此基础上通过高温分解制备纳米氧化铅。通过实验确定了制备碳酸铅的最佳工艺条件：反应温度95℃,反应时间5h,反应物浓度0.5mol/L,反应物摩尔比为1：6。热分解制备氧化铅的条件为420℃下分解3h。运用TEM对合成的碳酸铅形态及颗粒尺寸大小进行表征。TEM图像表明,制备的碳酸铅为斜方晶体,粒径为1μm-15μm,纳米氧化铅为球形,粒径为1nm-15nm。     

微/纳米ZnO粉体在Glu-BF_4离子液体水溶液中的诱导生长

以一定浓度谷氨酸-氟硼酸(Glu-BF_4)离子液体水溶液为反应介质,摩尔比为1∶6的二水合醋酸锌和氢氧化钠为反应物,在室温下制备前驱体,再通过微波辅助加热制备了具有绒球形貌的微/纳米ZnO粉体.利用扫描电子显微镜(SEM)、X射线衍射仪、比表面积测试仪、能谱仪、拉曼光谱仪和透射电子显微镜(TEM)等对产物形貌、晶型、比表面积、组成和晶面分布进行了测定.结果显示,所得产物为六方晶系纤锌矿结构,平均粒径20.4 nm,绒球大小1.6~3.0μm,比表面积为28.3 m~2/g,产物纯度较高.当反应物浓度一定,离子液体浓度分别为0.02,0.04,0.08和0.12 mol/L时都得到了类似形貌的微/纳米ZnO粉体,且随着离子液体使用量的增加,绒球尺寸分布更加均一.当离子液体浓度一定,而反应物浓度逐渐下降时,产物形貌发生递变性变化.ZnO晶粒在Glu-BF_4离子液体诱导下首先生成不规则的纳米片,纳米片进一步聚集,在一定反应物浓度范围内生成绒球形貌粉体,反应物浓度较低时只生成绒球的核心部分,而浓度更高时则生成纳米针阵列.通过不同条件下纳米ZnO粉体形貌变化规律,探讨了强碱性条件下Glu-BF_4离子液体水溶液中微/纳米ZnO粉体的生长机制.     

络合法制备纳米硫酸钡及其影响因素的分析

以Na2SO4和BaCl2为原料,EDTA为络合剂,水为反应介质,采用络合法制备纳米BaSO4。并研究了反应物浓度、体系pH、反应温度、滴加速度和干燥方式等因素对产物粒径大小和粒径分布的影响。通过考察和分析,初步得出纳米BaSO4最佳制备条件为:反应温度为35℃,pH为6,3种反应物EDTA、BaCl2、Na2SO4的反应浓度均为0.5 mol/L。     

锌-钬共掺杂无机抗菌材料的制备及性能研究

采用溶胶-凝胶法制备了一种新型无机抗菌材料--锌-钬抗菌白炭黑。通过单因素实验和响应曲面法优化,得到了最优制备条件为:锌浓度0.711 mol·L^-1,钬浓度0.5 mmol·L^-1及反应时间65 min。获得了分散性好、粒度较小、抗菌性能良好的复合抗菌材料。通过SEM,EDS,FTIR,粒径检测和抗菌检测等手段对锌-钬抗菌白炭黑进行了表征。结果表明:锌-钬抗菌白炭黑结构蓬松,平均粒径为28.948μm,且锌离子和钬离子的添加对载体白炭黑的结构基本没有影响,其抗菌率可达83.41%。     

电位型痕量硫氢根模拟酶生物传感器研究

以恒电位法在pH=9.0碱性水溶液中碳纤维簇电极上镀单层锌,在含有组氨酸和电解氧化锌镀层下原位合成了锌-组氨酸-羟基络合物修饰碳纤维电极,模拟了生物酶识别痕量的硫氢酸根离子,优化了电极制备的条件。建立了开路电位测定硫氢酸根离子的方法,在中性水溶液中,该电极以开路电位变化响应注入溶液中的硫离子浓度,并可用能斯特方程描述开路电位变化的规律。方法的最低检出限为1.0×10~(-15)mol/L,检测范围为1.0×10~(-6)~1.0×10~(-15)mol/L,相对标准偏差为3.5%。对实际样品中硫氢酸根离子检测结果为1.12×10~(-13)mol/L,加标回收率为109.2%。研制的电化学传感器具有响应快速,灵敏度高,检出限低,检测范围宽,仪器简单方便等特点。     

生物模板法制备纳米氧化锌及其表征

本文以油菜花粉为生物模板,硝酸锌为锌源制备了一种分级多孔结构的纳米氧化锌。采用SEM、TEM、XRD和 FTIR等技术手段对其进行了表征。实验结果表明,采用油菜花粉为生物模板制备的氧化锌纳米材料为六方纤锌矿结构,较好的复制了花粉的分级多孔结构。同时,研究了制备条件诸如煅烧温度和反应物浓度对产物结构、形貌和尺度的影响。     

小尺寸金纳米棒的快速制备及影响因素的研究

通过研究十六烷基三甲基溴化铵、抗坏血酸、NaBH4和AgNO3的用量,以及搅拌时间、反应时间对无种子生长法制备金纳米棒的影响,筛选出了最佳制备条件,以及各成分对金纳米棒生长过程中的作用.采用可见吸收光谱和透射电镜图对不同条件下所制备出的金纳米棒进行了表征.在室温为28℃,CTAB浓度为0.1 mol/L、AgNO3浓度为96μmol/L、AA浓度为0.97 mmol/L、NaBH4浓度为1.5μmol/L,搅拌25 s等最佳条件下,只需反应6h就能够成功制备出长径比为5且形貌均匀、分散性和稳定性良好、轴宽较小的金纳米棒,且有望应用于水环境中Hg2+的检测.     

生物模板法制备纳米氧化锌

本文以油菜花粉为生物模板、硝酸锌为锌源制备了一种分级多孔结构的纳米氧化锌。采用SEM、TEM、XRD和FTIR等技术手段对其进行了表征。实验结果表明,采用油菜花粉为生物模板制备的氧化锌纳米材料为六方纤锌矿结构,较好地复制了花粉的分级多孔结构。同时,研究了制备条件诸如煅烧温度和反应物浓度对产物结构、形貌和尺度的影响。     

超声复凝聚法制备海藻酸钠-明胶-维生素B1纳米胶囊

采用超声复凝聚法制备了海藻酸钠-明胶-维生素B₁纳米胶囊。采用控制单因素变量法探讨了明胶浓度、海藻酸钠浓度、维生素B₁浓度、pH、固化时间、温度等因素对胶囊包封率的影响,并通过正交试验确定了制备纳米胶囊的最佳工艺条件为明胶浓度0.8%、海藻酸钠浓度0.8%、维生素B₁浓度2.5%、pH为4.2、固化时间15min、温度55℃。制备的纳米胶囊包封率为42.68%,载药量为31.27%。     

基于氧化锌/碳纳米纤维材料的氧氟沙星电化学传感器的构建及应用

通过静电纺丝技术合成碳纳米纤维,以循环伏安法在此碳纤维上电聚合乙酸锌制备复合纳米材料作为一种新型的电化学增敏剂,用于修饰玻碳电极,开发了一种基于碳纤维和氧化锌复合材料的新型电化学传感器(ZnO/CNF/GCE)。使用循环伏安法、差分脉冲伏安法等进行电化学催化性能的研究,并优化实验条件。结果表明,与裸电极相比,在pH 5.5磷酸盐缓冲溶液中,ZnO/CNF/GCE修饰电极能使氧氟沙星的峰电流明显提升,线性范围1~200μmol/L,检测限为0.33μmol/L。该ZnO/CNF/GCE修饰电极已用于氧氟沙星滴耳液中氧氟沙星的含量测定。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

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.     

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%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

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.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.