碳点的性质及其在化学发光分析中的研究进展

碳点是一种新型的荧光碳纳米颗粒,与传统的半导体量子点相比,碳点具有毒性低、生物相容性好、原料丰富廉价、光稳定性好等特点,得到引了化学、材料和生物等各领域科学家的高度关注。 本文介绍了碳点的基本概念和性质、探讨了碳点在化学发光领域的应用研究进展并进行了展望。     

地沟油制备有机稀土化合物及其摩擦学性能研究

以地沟油为原料,制备了一种油溶性有机稀土化合物(ORE),并通过红外光谱和等离子发射光谱对其化学结构和元素组成进行了表征。用万能摩擦磨损试验机考察了有机稀土化合物在液体石蜡中的摩擦学性能,结果表明:有机稀土化合物作为润滑添加剂具有比ZDDP更好的抗磨减摩性能,有望作为新型的环境友好型润滑添加剂在工业实际中得到应用。当基础油中加入1.0%ORE时,其减摩性能和抗磨性能分别提高23%和34%,其承载能力是基础油的2.4倍。分析认为有机稀土化合物在摩擦过程中形成的含稀土的边界润滑膜可能是其具备良好极压抗磨和减摩效果的主要原因。由地沟油制备环境友好型润滑添加剂,是探索地沟油资源化利用技术的有益尝试,具有良好的推广应用前景。     

荧光碳点的制备方法及其在生物医药领域应用的研究进展

近年来,随着科学技术的不断发展,人们对于纳米碳材料的探索与开发日益增多。荧光碳点作为一种新型的纳米碳材料逐渐出现在大众视野之中,因其具有优异的光学特性、物理与化学性质均较为稳定、生物相容性高,同时拥有高效、无毒或低毒的制备方法而在药物载体、生物成像、探针检测等领域均得到了广泛的应用。本文针对近年来荧光碳点制备方法以及其在生物医药领域的应用进行综述,对荧光碳点的研究前景进行了展望。     

表面修饰LaF_3纳米微粒的制备及表征

在水醇混合介质中采用同阳离子共沉淀表面修饰法制备了有机化合物表面修饰的LaF3纳米微粒 ,研究了它的摩擦学特性。采用多种分析手段表征了表面修饰LaF3纳米微粒的结构 ,并在四球摩擦试验机上考察其润滑性能。结果表明 ,表面修饰LaF3纳米微粒不仅在有机溶剂中具有良好的分散性 ,同时也显示出良好的减摩、抗磨和承载性能。     

碳点的研究进展

碳点具有优良的光学特性、良好的生物相容性和低毒等优点,被广泛用于生物检测、药物传输和生物成像等领域,是极具发展潜力的碳基质材料.近年来,碳点的新型制备方法、性质探索及应用研究引起广泛关注.本文根据碳源和制备方法的不同,将碳点分为石墨烯纳米点和碳纳米点两类,综述了碳点的制备方法,剖析了碳点的发光机理,总结了碳点在生物传感、药物传输和生物成像中的应用;最后分析了碳点存在的问题及应对策略.     

两种无灰型含磷/硫润滑添加剂在菜籽油中的摩擦学性能及膜分析

以合成的两种无灰型含磷/硫化合物为润滑添加剂, 以可生物降解的菜籽油作为基础油, 用四球机研究了体系的抗磨减摩性能, 以X射线光电子能谱(XPS)和X射线吸收精细结构光谱(XANES)对所形成的摩擦膜和热膜进行了表面分析, 并初步探讨了其润滑机理. 摩擦学研究结果表明, 两种含磷/硫化合物作为菜籽油的润滑添加剂时, 具有良好的抗磨减摩性能. XPS和XANES分析结果显示, 摩擦膜和热膜主要由吸附层和反应层组成; 在表面膜中, 磷主要以磷酸盐或焦磷酸盐等形式存在, 而硫主要以硫酸盐的形式存在. 研究结果还表明, 摩擦热在两种不同添加剂的摩擦膜形成过程中发挥着不同的作用.     

纳米金刚石的表面修饰及应用

纳米金刚石是一种新型的碳纳米粒子,具有硬度高、化学稳定、良好的生物相容性和热传导性等优点,有广阔的应用前景。对于纳米金刚石的应用,大多需要对其进行表面修饰。本文主要结合近年来国内外研究成果,阐述了氢化、羧酸化、羟基化及其他表面修饰等纳米金刚石的表面修饰方法,总结了纳米金刚石在润滑、抛光、生物医学、复合材料等领域的应用。     

La2（C2O4）3纳米微粒的摩擦学行为研究

纳米摩擦学是９０年代摩擦学研究最活跃的领域之一［１］。稀土元素由于具有４ｆ电子特性,使其元素及其化合物具有许多特殊的性能［２～８］。本研究采用吸附共沉淀表面修饰法制备了烷基磷酸盐修饰的Ｌａ２（Ｃ２Ｏ４）３纳米微粒,并将其分散于润滑基础油中考察其摩擦学行为。利用有机脂肪链的减摩、纳米微粒的抗磨以及稀土元素的特殊作用,提高润滑油的摩擦学性能,拓宽稀土化合物在润滑材料领域的应用。１　实验部分１１　表面修饰Ｌａ２（Ｃ２Ｏ４）３纳米微粒的制备在醇水混合溶剂中,加入一定量的烷基磷酸吡啶盐（自制）和草酸盐…     

高聚物固体减摩材料研究进展

评述了近年来部分固体减摩、抗磨材料的种类及其应用，总结了现阶段在摩擦学研究领域中所取得了主要进展和成果。介绍了摩擦学领域中具有发展前途的几种新技术、新方法。     

镧－硼复合润滑添加剂的协合润滑机理

实验室和工业试验表明，含镧的润滑添加剂二烷基二硫代磷酸镧（ＬａＤＤＰ）和一种有机硼酸酯（ＯＢ）具有显著的协合润滑作用，将两种化合物复合加至润滑油中，可显著改善油品的抗磨减摩性能。采用俄歇电子能谱（ＡＥＳ）和Ｘ射线光电子能谱（ＸＰＳ）研究其协合润滑机理。结果表明，ＬａＤＤＰ和ＯＢ具有协合润滑作用的主要原因，除了在摩擦表面生成硫酸盐、磷酸盐、氧化镧和单质硼等表面膜起润滑作用外，更重要的是镧的存在对硼的摩擦扩散起到了“摩擦催渗”作用，使摩擦亚表面硼的含量增加，并形成Ｌａ－Ｂ摩擦共渗层，进一步提高材料表面硬度，从而改善耐磨性能     

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%.     

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.     

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.     

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.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

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.