CdTe量子点对胰凝乳蛋白酶的荧光标记

用巯基丙酸作为表面修饰剂在水相中制备了稳定的CdTe纳米量子点.利用量子点外层包被的巯基丙酸上的羧基,实现了量子点与胰凝乳蛋白酶的直接偶联.偶联后溶液的吸光度值略有增大而吸收峰位不变,同时荧光强度明显增强,荧光发射峰位稍有蓝移.通过荧光发射光谱确定了CdTe量子点与胰凝乳蛋白酶偶联的最佳反应条件为:pH 9.0,反应温度37℃,反应时间1.5 h.重点考察了NaCl浓度和胰凝乳蛋白酶浓度对量子点与胰凝乳蛋白酶偶联产物荧光强度的影响.     

不同环境因素对水热法合成碲化镉量子点的影响

对比了不同巯基稳定剂和前体浓度对水热环境CdTe量子点的生长过程和光物理性质的影响。结果表明,巯基丙酸与镉前体的结合能力较强,一定程度上减小了前体溶液中镉的浓度,故CdTe量子点生长速率较慢;空间位阻较大的硫普罗宁与镉前体的结合相对较弱,因此导致CdTe量子点生长较快。巯基丙酸有利于制备发光波长较短的高荧光强度CdTe 量子点,而硫普罗宁有利于制备发光波长较长的高荧光强度CdTe量子点。前体浓度对CdTe量子点的生长速率和光物理性质的影响不明显。在上述实验结果基础上,考察了水溶性乙酸钠和聚丙烯酸钠电解质对水热环境中CdTe量子点的生长过程和光物理性质的影响。结果表明,添加乙酸钠后可提高CdTe量子点的生长速率,进而导致CdTe量子点的表面重构和钝化能力下降,使荧光强度降低;聚丙烯酸钠对镉单体独特的固定作用导致CdTe量子点生长缓慢,尺寸集中化受限,钝化能力降低,使荧光强度下降更加明显。     

表面修饰CdTe量子点的合成及其光学特性

在水相中合成高发光性能的CdTe量子点,研究以巯基乙酸(TGA)为稳定剂对CdTe表面进行修饰,制备在水中分散性良好的纳米晶,通过对CdTe量子点合成反应条件的摸索,掌握了其合成的反应规律.同时用紫外分光光度计、荧光分光光度计和透射电子显微镜对其进行了表征.结果表明,回流时间、n(Cd²⁺):n(HTe^-)、反应物浓度、TGA用量、反应体系pH值,对纳米晶的光学性质具有显著影响.回流2 h制得的CdTe纳米粒子直径约为5 nm,其发射峰窄且对称,表现出良好稳定的光学性质.     

超声电化学快速制备近红外CdTe量子点与细胞成像

针对当前水溶性量子点合成路线复杂、量子产率低的现状, 在无需N₂保护的条件下, 采用简便的超声电化学方法快速合成了CdTe量子点前驱体;并对不同条件下制得的前驱体加热回流, 得到水溶性、高质量的近红外CdTe量子点。产物的形貌、结构和组成通过高分辨透射电子显微镜(HRTEM)、X-射线粉末衍射(XRD)等手段进行了表征。考察了超声电化学参数和回流条件对量子点荧光性质的影响。通过控制电流脉冲宽度、反应时间、反应温度等参数, 实现了CdTe量子点前驱体的可控制备;通过调节加热回流条件得到不同荧光发射波长的量子点;选用602 nm近红外发射波长的CdTe量子点标记了子宫颈癌细胞(Hela), 并采用共聚焦技术实现了肿瘤细胞的显微成像观察。和传统的量子点合成方法相比, 超声电化学方法具有合成路线简单、参数易调可控的特点;为高品质量子点的快速制备提供了新的思路, 拓展了超声电化学在纳米材料制备领域的应用。     

超声电化学快速制备近红外CdTe量子点与细胞成像

针对当前水溶性量子点合成路线复杂、量子产率低的现状,在无需N2保护的条件下,采用简便的超声电化学方法快速合成了CdTe量子点前驱体;并对不同条件下制得的前驱体加热回流,得到水溶性、高质量的近红外CdTe量子点。产物的形貌、结构和组成通过高分辨透射电子显微镜(HRTEM)、X-射线粉末衍射(XRD)等手段进行了表征。考察了超声电化学参数和回流条件对量子点荧光性质的影响。通过控制电流脉冲宽度、反应时间、反应温度等参数,实现了CdTe量子点前驱体的可控制备;通过调节加热回流条件得到不同荧光发射波长的量子点;选用602 nm近红外发射波长的CdTe量子点标记了子宫颈癌细胞(Hela),并采用共聚焦技术实现了肿瘤细胞的显微成像观察。和传统的量子点合成方法相比,超声电化学方法具有合成路线简单、参数易调可控的特点;为高品质量子点的快速制备提供了新的思路,拓展了超声电化学在纳米材料制备领域的应用。     

水热法合成CdTe量子点及其与蛋白质连接作为生物荧光探针的研究

以巯基丙酸为稳定剂,采用水热法合成了CdTe量子点.吸收光谱和荧光光谱表明,所合成的CdTe量子点具有优异的发光特性.透射电子显微境(TEM)表征了纳米微粒的结构和粒径分布.并以牛血清白蛋白(BSA)为代表,通过测定CdTe量子点与BSA偶联(QDs-BSA)后溶液的荧光强度确定CdTe量子点与蛋白质偶联的最佳反应条件为pH 9～10,反应温度37 ℃,反应时间2 h.通过荧光发射光谱研究了溶液pH和NaCl浓度对QDs-BSA溶液和QDs溶液荧光强度的影响.在优化的反应条件下,用制备的QDs-BSA荧光探针对BSA进行了定量测定,线性范围是0.06～0.48 μg/mL,对0.24 μg/mL QDs-BSA样品7次测定的相对标准偏差是2.2%.     

生物相容的高荧光CdTe量子点的合成和表征

用硫普罗宁(tiopronin,TP)作为稳定剂,在水相中合成了荧光发射波长可调的高荧光CdTe量子点。本文详细地研究了稳定剂与Cd之比和pH值等实验条件对CdTe纳米粒子体系的荧光量子产率的影响。在pH=11.3回流2 h,纳米粒子体系在537 nm波长处的荧光量子产率达到了66%。通过控制实验条件,合成了各种尺寸的CdTe量子点,荧光发射光谱在504~602 nm范围连续可调。分别用X射线光电子能谱(XPS)、透射电子显微镜(TEM)、X射线衍射(XRD)、红外吸收光谱(FTIR)表征了CdTe粒子的分散性、形貌和晶型。溶血实验显示,这些由硫普罗宁稳定的CdTe量子点几乎不发生溶血作用(溶血率低于5%),具有良好的生物相容性。     

碲化镉量子点作为探针研究核黄素与鲑鱼精DNA的相互作用

在水相中合成了巯基丙酸包覆的CdTe量子点（CdTe QDs）,以CdTe QDs作为探针,在pH 7.25 Britton-Robinson（B-R）缓冲溶液中,应用荧光光谱法、紫外吸收光谱法,对核黄素（RF）与鲑鱼精DNA作用方式进行了研究.RF与DNA作用时,使荧光强度降低,紫外吸收明显减色,通过盐效应实验和DN...     

CdTe/CdSe核壳量子点的合成及其在指纹显现中的应用

以CdCl2和Te粉为原料,在水相中合成了CdTe量子点核;通过外延生长在CdTe量子点核上包覆一层CdSe量子点,得到具有良好荧光性能的CdTe/CdSe核壳量子点;采用X射线衍射仪、透射电镜、高分辨透射电镜分析了不同反应条件下合成的CdTe/CdSe核壳量子点的晶体结构和微观结构,并对其进行了荧光光谱等测试和指纹显现分析.结果表明,合成的CdTe和CdTe/CdSe量子点粒径在3～5nm之间,粒径分布窄,水分散性良好;可以通过控制反应时间和Te/Se比等得到在500～700nm显示荧光发射峰的CdTe/CdSe核壳量子点.此外,核壳CdTe/CdSe量子点可以有效地和指纹物质结合,可应用于对铝合金油潜指纹的鉴别.     

高质量CdTe量子点的水相快速合成

系统考察了水相合成CdTe量子点的主要影响因素, 通过改变无水乙醇-水体系的体积, 提高NaHTe的合成质量, 并调整反应温度, 改变反应的初始pH值, 在水相中快速合成了量子产率高、粒径分布范围窄的CdTe量子点, 实现了对量子点发光性质的调控, 在最佳条件(无水乙醇3 mL, 水1 mL, 反应初始pH 8.0, 反应温度40 ℃)下, 最高量子产率达68%. 量子点胶体溶液在回流过程中有时产生白色沉淀, 放置7 d后, 未过滤白色沉淀的量子点比过滤后的量子点荧光强度提高15%, 白色沉淀还有减小粒径分布的作用.     

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.