水热法快速合成绿色到近红外发光CdTe量子点

以3-巯基丙酸(MPA)和柠檬酸钠为稳定剂,Na2TeO3为碲源,利用水热法成功制备了从绿色到近红外发射的CdTe量子点,并详细探讨了影响CdTe量子点体系的荧光发射波长和量子产率的因素,如反应前驱液的pH值,反应物的浓度比和反应时间等实验条件.分别用X射线粉末衍射、透射电镜、紫外-可见光谱和荧光光谱对CdTe量子点进行了表征.     

基于CdTe量子点荧光探针测定水样中痕量Cd2+

本文以巯基乙酸为稳定剂,在水相中合成水溶性的CdTe量子点(CdTe QDs),并基于QDs荧光增强原理,建立了QDs荧光探针测定水中痕量Cd2+的新方法。研究表明,在pH为7.8的硼酸-硼砂缓冲溶液和吐温-40的存在下,Cd2+能够显著增强CdTe QDs的荧光强度,且Cd2+浓度在2.0×10-7～5.5×10-5g/L范围内与CdTe QDs荧光增强强度呈现良好的线性关系,相关系数为0.9988,检出限(3s/k)为3.2×10-8 g/L。该方法简单便捷,灵敏度高,应用于实际水样的检测,回收率为96.0%～102.5%。     

CdTe/CdS量子点荧光探针测定司帕沙星含量

在水溶液中合成了巯基乙酸修饰的CdTe/CdS量子点(QDs), 基于喹诺酮类抗生素司帕沙星与CdTe/CdS量子点的荧光猝灭作用, 建立了用CdTe/CdS量子点作为荧光探针检测微量司帕沙星的新方法. 用荧光光谱、紫外光谱研究了CdTe/CdS QDs与司帕沙星的相互作用. 研究表明: 该荧光猝灭的机理属于静态猝灭, 反应的作用机理可能是司帕沙星促使QDs表面键合的有机分子发生变化, 在Cd的电子空穴上形成了碲氧复合物, 致使荧光猝灭. 实验发现, pH为6.50的磷酸缓冲溶液中, 量子点的浓度为3.75×10^－4 mol/L时, 司帕沙星的浓度在0.1～50 μg/mL范围与CdTe/CdS量子点荧光猝灭强度呈良好的线性关系, 相关系数0.9992, 检出限0.01399 μg/mL. 该方法简便、快捷、灵敏、线性范围宽, 应用于司帕沙星片剂司帕沙星含量的测定, 分析结果与标示量一致; 用于牛奶中司帕沙星残留量的检测, 回收率在93.1%～102.4%, 结果满意.     

一锅合成绿色到近红外发射的CdTe量子点

以3-巯基丙酸(MPA)为稳定剂,采用水相合成法制备了从绿色到近红外发射的CdTe量子点。系统研究了反应液pH值、镉和碲的物质的量之比及镉和3-巯基丙酸的物质的量之比等实验条件对CdTe量子点体系的发射波长和荧光量子产率的影响。在pH值为10.5,且nCd2+∶nTe2-∶nMPA=1∶0.05∶1.1的条件下,回流0.5 h,CdTe量子点体系在569 nm波长处的荧光量子产率达到30.8%;在7 h的回流时间内,制备的量子点的波长覆盖范围为525～730 nm。分别用X射线粉末衍射、透射电镜和红外光谱对CdTe量子点的晶体结构、形貌及表面基团进行表征。     

CdTe量子点与罗丹明6G荧光共振能量转移体系的构建及机理研究

以巯基乙酸为修饰剂,水相合成不同尺寸的CdTe量子点(QDs),研究不同发射波长的CdTe QDs与罗丹明6G(R6G)之间的荧光共振能量转移(FRET)规律。结果发现,以发射波长为515nm的CdTe QDs为供体与R6G能量转移效率为58.5%,以R6G为供体与发射波长为605nm的CdTe QDs能量转移效率为49.4%,即在CdTe QDs-R6G的FRET体系中,量子点既可作为供体也可作为受体。在此基础上,构建了CdTe QDs(供体)-R6G(第一受体)-CdTe QDs(第二受体)的三元FRET体系,并研究了其双荧光共振能量转移的机理。     

CdTe量子点荧光光度法测定诺氟沙星的含量

在水溶液中合成了巯基乙酸修饰的CdTe量子点,基于铝敏化喹诺酮类抗生素,研究了诺氟沙星与CdTe量子点的荧光增敏作用,建立了用CdTe量子点作为荧光探针检测微量诺氟沙星的新方法。该体系的最大激发波长λex=365nm,最大发射波长λem=586nm。诺氟沙星溶液的浓度在9×10-3～2.4μg·mL-1范围内与体系荧光强度呈良好的线性关系,检出限为4.5×10-3μg·mL-1,相对标准偏差为0.9%。本方法灵敏度较高,选择性较好的,可用于药物中诺氟沙星含量的测定,结果较为满意。     

硫脲修饰法制备高发光性能CdTe量子点

通过巯基水解制备了具有优异荧光特性的碲化镉量子点. 详细研究前驱体镉离子与巯基丙酸(MPA)摩尔比、镉离子浓度等制备条件对大尺寸、高量子产率的亲水性碲化镉量子点光学性能的影响. 在不同的水热生长时间下, 可制备出荧光发射峰位于485-660 nm范围内的不同尺寸的碲化镉水溶性量子点, 荧光发射峰半高宽控制在40-75 nm之间, 量子点的最高量子产率(QY)达到了45%. 并利用硫脲缓慢水解和光解释放自由硫离子, 修饰碲化镉表面, 检测修饰后的量子点在12天内光学性能的变化情况. 通过考察硫脲用量对量子点修饰效果, 发现当n(CdTe)/n(thiourea)=1:4(量子点浓度以镉离子浓度计)时, 硫脲对发射峰为505 nm的碲化镉量子点修饰效果最为理想, 量子点荧光强度加强了5倍, 量子产率达到68.3%.     

颜色可调的高荧光CdTe量子点的水相合成

以亚碲酸钠为碲源,硼氢化钠为还原剂,一步合成了巯基丁二酸(MSA)稳定的CdTe量子点.研究了反应液pH值、镉与碲的摩尔比及镉与巯基丁二酸的摩尔比等实验条件对CdTe量子点体系荧光量子产率的影响,并用荧光光谱、X射线粉末衍射及透射电子显微镜等对其进行了表征.结果表明,CdTe量子点具有闪锌矿结构,形貌呈球状;在pH=1...     

水溶性量子点的制备及其与壳聚糖衍生物的自组装

以3-巯基丙酸(HS-CH2CH2COOH)为稳定剂, 制备了水溶性的碲化镉(CdTe)量子点(QDs), 考察了制备条件对QDs荧光性能的影响及CdTe QDs与壳聚糖及叶酸和聚乙二醇改性的壳聚糖的自组装. 研究发现, 壳聚糖及改性壳聚糖与QDs的复合物荧光强度相对纯的CdTe QDs明显增强, 且QDs被包裹在内核, 复合粒子呈明显的核/壳结构. 改性壳聚糖/QDs复合物较小且尺寸分布更为均一.     

双量子点纳米复合物NO比率荧光探针的合成与应用

通过静电吸附作用,合成了CdSe@SiO_2-CdTe双量子点的纳米复合物.一氧化氮(NO)与CdTe量子点表面Cd离子结合形成Cd-NO复合物,引起CdTe量子点荧光猝灭,而不影响CdSe量子点的荧光.当NO浓度在0.1~2.2μmol/L之间变化时,该探针荧光强度比值I_(603)/I_(532)符合线性关系(R=-0.995 4),从而实现对NO的定量检测.     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.