具有红光发射的稀土上转换发光纳米晶及其介孔直接功能化

红光发射稀土上转换发光纳米晶(UCNPs)在光动力治疗(PDT)等方面具有特定的优势。将油溶性的UCNPs通过表面改性转变为水溶性,对其在生物医疗、疾病诊断等方面的应用具有重要意义。利用一种简单易行的方法将具有红光发射的UCNPs进行介孔直接功能化表面修饰,制备了一种具有良好水溶性的纳米材料NaYF4:Yb/Er/Mn@mSiO2。实验结果表明该材料核-壳结构明显,形貌均一,在980 nm的激发下保持了上转换发光特性。该材料在光动力治疗等方面具有良好的潜在应用价值。     

等离子体增强上转换发光及其应用

稀土上转换纳米材料（UCNPs）是一类在近红外光激发下发出可见光的纳米材料。与有机荧光染料、量子点等发光材料相比,UCNPs具有化学稳定性高、光稳定性强、荧光寿命长、反斯托克斯位移大、发光谱带窄和光穿透深度大等诸多优点,在生物成像、传感器、激光器、光动力疗法和太阳能电池等领域有潜在的应用价值。但是由于UCNPs激活离子的吸收截面太小,导致其发光效率偏低,限制了UCNPs的进一步应用。因而如何提高上转换发光强度成为当前的研究热点。针对上述问题,本文系统阐述了金属表面等离子体共振（SPR）增强上转换发光领域的研究进展。首先介绍了SPR增强上转换发光的三种机制,随后重点介绍了化学法和物理法这两种SPR-UCNPs体系的构建方法以及其在太阳能电池、生物成像、生物检测、光热治疗和光催化等领域的应用。文章最后指出了SPR增强上转换发光领域存在的不足和未来的研究方向。     

脑内三磷酸腺苷的光电化学活体分析北大核心CSCD

神经化学信号传递是实现大脑复杂功能的基础,因此发展神经化学信号的活体原位检测方法,对于探索脑功能和脑疾病的神经化学分子机制具有重要意义。光电化学传感技术具有灵敏度高、背景信号低和易于微型化等优点,是活体原位分析的潜在有力工具。然而,常见的光电活性材料需要短波长的光激发,其组织穿透深度不足,限制了在活体分析中的应用。基于此,本文构建了一种可近红外激发的光电化学微传感器,用于脑内三磷酸腺苷(ATP)的原位检测。将稀土掺杂的上转换纳米颗粒(UCNPs)引入传感界面,用UCNPs的发光激发电极表面的光电活体材料产生光电流信号,通过荧光染料(TAMRA)标记的核酸适配体调节UCNPs的发光,发展一种基于光学调控策略检测脑内ATP的光电化学传感新方法。所制备的微传感器成功用于炎症模型中小鼠脑内ATP的原位检测,初步探索了脑部炎症与ATP水平变化的关系。     

掺杂比例和光敏剂对上转换纳米材料性能的影响

以NaYF_4材料为基质的上转换纳米颗粒(UCNPs)是最早报道的、应用范围最广的上转换材料之一。掺杂了稀土离子的颗粒不但可以在不同激发条件下发射出不同波长和强度的荧光,而且可以与多种光敏分子搭配使用,通过荧光共振能量转移产生单线态氧,实现生物医学成像或诊疗方面的应用。但是其形貌和荧光性能均受制备方法和工艺条件的影响较大。本文通过水热法合成了两类掺杂不同稀土离子的十种NaYF_4 UCNPs,在保持掺杂离子的终浓度不变的条件下,探究离子类型与比例对纳米材料的结构和上转换发光性能的影响。在此基础上,探索了多种卟啉类光敏剂分子与NaYF_4 UCNPs发生能量转换及单线态氧的产生能力。本工作可为基于NaYF_4材料的上转换颗粒的规模化制备和工艺升级提供数据支撑和理论参考。     

优化稀土上转换纳米材料发光的方法

稀土上转换纳米材料(Upconversion Nanoparticles,UCNPs)可将近红外光转换为可见光,其发光性能优异、化学性质稳定、激发光能有效避免自荧光,因此在生物医学领域应用广泛。但UCNPs的低发光效率限制了其进一步发展。本文综述了近年来研究较多的几种优化稀土上转换纳米材料发光的方法,主要包括调整基质材料和掺杂离子、过渡金属离子与镧系离子共掺杂、引入协同敏化剂减少热效应、有机染料与UCNPs协同作用以及金属表面等离子体共振增强法等。文中分别论述了上述方法的最新研究进展,并总结了这些方法目前存在的问题,指出上转换发光领域的研发重点:一是着重分析各种优化发光方法的作用机理,提出更加完备清晰的理论体系;二是探索更容易被生物体降解的UCNPs,使其副作用降到最低。     

稀土上转换发光纳米材料的应用

稀土上转换发光纳米材料(简称UCNPs)不仅光稳定性强、发射带窄、荧光寿命长、化学稳定性高、潜在生物毒性低,而且采用近红外连续激发光源激发还使其具有较大的光穿透深度、无光闪烁和光漂白、无生物组织自发荧光以及对生物组织几乎无损伤等显著优点,已经成为当前很多领域乃至交叉科学的应用研究热点。由于氟化物基质的UCNPs具有较高的发光效率,本文首先归纳总结了近年来氟化物UCNPs的主要合成及表面改性方法,然后重点综述了近年来UCNPs在免疫分析及生物传感、生物成像、载药、光动力理疗及热致理疗、光导开关和信息存储以及太阳能电池等方面的研究与应用进展。     

稀土离子掺杂的AgLa(WO4)2枝状纳米材料的合成与上转换发光性质

通过无模板的水热方法合成了AgLa(WO4)2树枝状纳米晶,没有表面活性剂等模板的介入,使反应变得简捷、绿色和经济. 综合利用多种测试手段对所得材料进行了表征,如X-射线粉末衍射,扫描电子显微镜,透射电子显微镜等,并根据实验结果的分析提出了扩散限制生长（DLA,diffusion-limited aggregation）模型. AgLa(WO4)2树枝状纳米晶可以作为稀土离子掺杂的主体材料,这种掺杂稀土离子（Yb3+, Er3+, Tm3+）的纳米晶在980 nm激光激发下展示丰富的上转换发光颜色. 根据上转换光谱详细研究了AgLa(WO4)2:RE3+树枝状纳米晶在980 nm激光激发下的上转换发光性质和发光机理.     

稀土上转换发光纳米材料的防伪安全应用

与有机荧光染料、量子点等传统发光材料相比,稀土上转换发光纳米材料(UCNPs)具有反斯托克斯位移大、发光谱带多且狭窄、荧光寿命长、光化稳定性高、无光闪烁和光漂白等独特优势,将其与图形编码、防伪印刷技术结合可获得难以仿冒的隐形荧光图案,这已经成为防伪安全领域的应用研究热点.本文首先介绍了UCNPs的上转换发光机理及其合成...     

稀土上转换发光材料标记抗体的制备及在免疫组化中的应用

采用微波辐射法合成了具有上转换发光特性的六方相纳米粒子NaGdF₄: Yb³⁺,Er³⁺(UCNPs), 其晶粒大小约为65 nm, 且粒子在980 nm的激发光下显示绿光(550 nm). 进一步在NaGdF₄: Yb³⁺,Er³⁺纳米晶的表面包覆了一层二氧化硅层, 进行氨基功能化后获得了表面共价结合氨基基团的粒径为70 nm的上转换发光纳米微球NaGdF₄: Yb³⁺,Er³⁺@SiO₂-NH₂(UCNPs@SiO₂-NH₂). 通过共价键将UCNPs@SiO₂-NH₂与多克隆抗体免疫球蛋白联接, 将标记后的多克隆抗体应用于传统的免疫组化检测子宫内膜腺细胞中基质金属蛋白酶组织抑制剂-4(TIMP-4)蛋白的表达. 结果表明, 微波合成的稀土上转换发光纳米材料形貌规则且粒径均一, 包覆硅壳后材料具有良好的分散性和水溶性, 荧光强度高且稳定, 在980 nm激发光下对生物组织无背景荧光, 可以很好地检测组织中蛋白质的表达.     

无机纳米稀土发光材料的制备方法*

无机纳米稀土发光材料作为一种重要的发光材料,由于具有独特的光、电和化学性质,使其在高性能磁体、发光器件、显示、生物标记、光学成像和光学治疗等方面得到了广泛的应用。稀土发光材料的这些性质与材料的尺寸和形状密切相关,近年来研究者已经利用多种合成方法制备了不同形状的纳米稀土发光材料,包括纳米线、纳米棒、纳米管、纳米纤维和纳米片等。本文综述了无机纳米稀土发光材料的几种常用的制备方法,包括水热/溶剂热法、有机/无机前驱体热分解法和超声辅助合成法等,评述了这些方法的优缺点,并结合课题组在无机纳米稀土发光材料制备方面的工作,对无机纳米稀土发光材料制备方法的发展进行了展望。     

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%.     

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.     

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.     

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

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.