罗丹明6G衍生物-谷胱甘肽荧光探针测定水中Hg2+

在罗丹明6G衍生物(Rh6G2)中引入谷胱甘肽(GSH),制备了一种荧光探针Rh6G2-GSH,并基于其与Hg2+识别时可发生荧光强度及吸光度的变化,分别采用荧光分光光度法和紫外-可见分光光度法测定水中Hg2+的含量.在由体积比为1:1的4-羟乙基哌嗪乙磺酸(HEPES)溶液和甲醇混合而成的缓冲溶液(pH 7)中加入R...     

两种不同光谱类型的R-藻红蛋白的荧光性质研究

红藻中的R-藻红蛋白(R-PE)依照其吸收光谱可分为两种不同的光谱类型,即“双峰型”和“三峰型”。本文通过对不同pH条件下的R-PE的荧光光谱及荧光寿命的研究,发现“三峰型”R-PE的pH稳定范围较“双峰型”R-PE大。在R-PE浓度对荧光光谱的影响实验中,随着蛋白浓度的增加,荧光峰位置逐渐红移。荧光寿命逐渐增大,荧光强度先行增加而后减弱。用碘离子对其荧光进行猝灭,随着碘离子浓度的增大,荧光强度逐渐降低,荧光寿命逐渐缩短,并服从Stem-Volmer规则。     

茜素红-硼酸配合物双重光谱响应测定微量铜离子

采用荧光光谱法和紫外可见吸收光谱法研究了Cu2 与茜素红(ARS)-H3BO3配合物间的相互作用。Cu2 使ARS-H3BO3配合物在587 nm处的荧光猝灭,并且溶液颜色由黄色变为红色。研究结果显示:Cu2 对ARS的强结合能力使ARS-H3BO3配合物分解,同时形成ARS-Cu2 配合物,致使体系的荧光光谱和吸收光谱均发生明显变化。Cu2 浓度在1.0×10-6~2.4×10-5mol/L范围内,体系荧光强度变化与Cu2 浓度呈现良好的线性关系,方法检出限为1.01×10-7mol/L。该方法用于废水中Cu2 的测定,回收率为95.5%~101.0%。     

罗丹明6G荧光猝灭法测定农产品中痕量铁

在稀硫酸溶液中,铁(Ⅲ)与碘化钾反应生成游离碘(以络阴离I-,3 状态存在).所释出的I-,3与罗丹明6G反应生成离子缔合络合物,导致罗丹明 6G 的荧光猝灭.在激发波长 483 nm 及发射波长 551 nm 处测定空白试液及含铁试样溶液的荧光强度F,o及F,s并算得荧光猝灭强度△F.试验结果表明:铁(Ⅲ)的质量浓度在 0.01～0.40 mg·L-1范围内与其相应的荧光猝灭值△F 之问呈线性关系,并测得其检出限(S/N=3)为 0.005 mg·L-1.应用此方法测定了3种农产品试样中的含铁量,并以此试样为基体加入铁(Ⅲ)标准溶液测定了方法的回收率在 95.7%～99.3%之间.     

荧光分光光度计的功能开发

固、液体吸收光谱测量的附件是由光阑、负透镜、全反射棱镜，吸收不也组成的光学系统，将它配置到进口荧光分光光度计上，可以扩展其功能，使其具有紫外分光光度计（ＵＶ）的功能，能够测量固体、液体样品的透射光谱和吸收光谱。     

荧光分光光度法测定环境水中痕量硫化物

在pH 9.10的氨性缓冲溶液中硫离子能导致荧光试剂水杨醛缩氨基硫脲荧光强度猝灭,荧光猝灭的程度随硫离子含量的增加而增大.其硫离子的质量浓度在20～440μg·L-1范围内与荧光强度的猝灭程度呈线性关系,方法的检出限(S/N=3)为6.7μg·L-1.据此建立了测定痕量硫化物的荧光猝灭分析方法.该方法操作简便、反应迅速、灵敏度高,可直接用于工业废水、自来水、井水中硫化物的测定.     

基于碳量子点荧光分光光度法检测叶酸

在pH 7.3磷酸盐缓冲介质中,通过静电作用,叶酸能猝灭碳量子点在384 nm处的荧光。其猝灭的荧光信号强度与叶酸浓度呈一定线性关系,据此建立了检测叶酸的荧光分光光度法。线性范围为0.025~2.0μmol/L,相关系数为0.9947,检出限为2.5 nmol/L。表征了体系的荧光光谱,吸收光谱及荧光寿命,探讨了体系的反应机理,优化了实验条件。本方法用于模拟血清中叶酸含量的检测,加标回收率为97.3%~101.6%,RSD≤4.9%。     

罗丹明6G酰肼Hg~(2+)荧光探针及细胞成像应用

合成了罗丹明6G酰肼并研究了各种金属离子对其吸收光谱和荧光光谱的影响,结果表明,罗丹明6G酰肼是一种高选择性汞离子荧光探针。在乙醇/4-羟乙基哌嗪乙磺酸缓冲溶液(pH=7.2,体积比1∶1)中,罗丹明6G酰肼本身无荧光,加入汞离子使其在554 nm产生强发射,发出明亮的黄绿色荧光。其他常见金属离子,包括重金属离子和过渡金属离子,对汞离子引起的荧光增强无影响。罗丹明6G酰肼还被用于活细胞中汞离子的检测。另外,汞离子能使罗丹明6G酰肼在530 nm产生强吸收,溶液由无色变为粉红色。     

苯海拉明与赤藓红相互作用的吸收、荧光和共振瑞利散射光谱及其分析应用

在pH 4.5的Britton-Robinson(BR)缓冲溶液中, 赤藓红(ET)与苯海拉明(DP)形成1: 1的离子缔合物, 不仅引起吸收光谱的变化和荧光猝灭, 更导致共振瑞利散射(RRS)的显著增强并产生新的RRS光谱, 最大RRS峰位于580 nm附近. 研究了反应产物的吸收、荧光和RRS光谱特征, 适宜的反应条件及分析化学性质, 据此发展了以赤藓红为光谱探针的灵敏、简便、快速测定DP的新方法. RRS法、分光光度法和荧光猝灭法对DP的检出限依次为0.0020, 0.088和0.094 μg/mL, 线性范围分别是0.0067 ~ 2.0, 0.29 ~ 6.4和0.31~3.2 μg/mL. 研究了苯海拉明与赤藓红相互作用对吸收、荧光和RRS光谱的影响. 散射光偏振实验显示结合产物在最大散射波长处的偏振度为0.9779, 表明DP-ET体系的共振散射光谱主要由散射光构成, 基本不含共振荧光成分. 还采用量子化学AM1法计算了反应前后生成焓和平均极化率的变化, 讨论了RRS光谱产生及增强的原因及光吸收、荧光和RRS之间的能量转换关系.     

钐配合物有序分子膜的激光诱导荧光研究

用Langmuir-Blodgett(LB)膜方法组装了可发红色荧光的钐配合物有序分子膜。用时间分辨技术得到了其激光诱导荧光光谱,并分析了荧光光谱的精细结构,计算了有序分子膜中钐离子的能级常数,测定了配合物中心离子的荧光寿命,从分子内及分子间能量转移机理上研究了分子存在状态、膜中组分对钐配合物荧光寿命及能级常数的影响。     

Spectroscopic properties and hydration of the Cm(III) aqua ion from 10 to 85 °C

The optical absorption, fluorescence excitation, and emission spectra of the Cm(III) aqua ion in 0.001 M perchloric acid were studied in pure H(2)O, pure D(2)O, and in mixtures of H(2)O-D(2)O at temperatures from 10 to 85 °C. The quantum yield of the fluorescence of the Cm(III) aqua ion in pure H(2)O and D(2)O was also measured in this temperature range and the radiative decay rate constant was obtained from these data. The results indicate that, from 10 to 85 °C, the effect of temperature on the absorption, excitation, and emission spectra is very small. By correcting the observed decay rate constant for the radiative rate constant, a set of correlations between the observed fluorescence decay rate constant and the hydration number of Cm(3+) in H(2)O at temperatures from 10 to 85 °C was developed. A weak temperature dependence was observed for the nonradiative decay rate constant for the (6)D'(7/2)-(8)S'(7/2) transition and described by the Arrhenius equation. The activation energy of the nonradiative decay was measured to be 0.9 kJ mol(-1), approximately matching the energy gap between the first and the second (A(1) and A(2)) levels of the metastable (6)D'(7/2) multiplet of the Cm(III) aqua ion. On the basis of these observations, it is postulated that the slight increase in the observed fluorescence decay rate constant as the temperature increases from 10 to 85 °C is due to the effect of thermal population of the A(2) level.     

Formation of nano‐dots of phenylazomethine dendrimers with Rhodamine 6G on mica

The phenylazomethine dendrimer (DPA) is associated with Rhodamine 6G in chloroform, which results in the chemical shift attributed to the aromatic protons of phenylazomethine being moved upfield in the ¹H‐NMR spectrum by increasing the Rhodamine 6G. The shift is saturated at the ratio of 1 : 1. On the basis of the NMR analysis, the association constant K of phenylazomethine with Rhodamine 6G was determined to be 1.4 × 10⁴ (l/mol) in CDCl₃ at 20°C. The association is also confirmed by UV‐vis spectroscopy, in which the absorption around 450 and 527 nm changes during the addition of Rhodamine 6G. The fluorescence intensity of the 1 : 1 complex of Rhodamine 6G and DPA G4 is stronger than that of the solution dissolved only in Rhodamine 6G at greater than 1 mM though it is generally known that the intermolecular interaction quenches the dye fluorescence in a concentrated solution. The association of DPA G4 with Rhodamine 6G suppresses the quenching at higher concentrations. Homogenous nano‐dots were observed on mica by casting the DPA G4 complex with Rhodamine 6G, in which the height and average area were 1.5–3 nm and 1.6 × 10³ nm² (the standard deviation σ = 3.7 nm²), respectively. Copyright © 2004 John Wiley & Sons, Ltd.     

Effect of the solvent composition in methanol-pentane and methanol-acetonitrile mixtures on the spectral and luminescent properties of 1,2-dihydroquinolines

The dependence of absorption and fluorescence spectra, quantum yields, and lifetimes of fluorescence on the solvent composition in the MeOH-C₅H₁₂ and MeOH-MeCN mixtures was studied for 2,2,4,6-tetramethyl-1,2-dihydroquinoline (TMDHQ). The variations in the parameters of deconvolution of the absorption and fluorescence spectra by the Gaussian functions in the MeOH-C₅H₁₂ mixtures of various compositions indicate the specificity of methanol clustering in saturated hydrocarbons and hydrogen bonding between TMDHQ and the methanol clusters of different compositions. At low MeOH concentrations (∼0.2 vol %), TMDHQ molecules are practically completely bound with the MeOH molecules by hydrogen bonds. In the MeOH-MeCN mixtures, the changes in the absorption and fluorescence spectra are observed at a substantially higher MeOH concentration (≥10 vol %) and monotonically change at the further increase in the MeOH concentration that is caused by the peculiarities of MeOH clustering in acetonitrile and the distribution of the TMDHQ molecules between the solvent components. At 50–95 vol % of MeOH in the mixture with MeCN, the fluorescence decay kinetics is described by the biexponential curve with the lifetime of the major component (τ₁) decreasing from 7.5 to 1.1 ns in pure MeCN and MeOH, respectively, and the lifetime of the minor component τ₂ ≈ 4 ns corresponding to the fluorescence lifetime in the solution containing 50 vol % MeOH. This indicates the existence of the free TMDHQ molecules, which are not bound with MeOH molecules or their clusters.     

核酸适配体封盖的介孔二氧化硅纳米颗粒用于肌红蛋白的检测

利用核酸适配体封盖的介孔二氧化硅纳米颗粒构建了一种新型、 简便及免标记的肌红蛋白定量检测方法. 首先, 用肌红蛋白核酸适配体将荧光小分子罗丹明6G封盖在介孔颗粒内, 当存在目标物肌红蛋白时, 由于介孔颗粒上的核酸适配体可特异性结合肌红蛋白而脱离介孔颗粒表面, 进而释放介孔颗粒内的罗丹明6G, 使溶液荧光强度增强. 实验结果表明, 荧光强度与肌红蛋白的浓度呈正相关, 通过荧光强度的变化可实现对肌红蛋白的定量检测. 该方法的检出限低至1.1 nmol/L, 且选择性好, 可满足临床医学的检测要求.     

在胶束形成前染料分子的能量转移与预胶束基本性质的研究

本工作对罗丹明6G(1)与罗丹明-B(2)两种染料在十二烷基硫酸钠(SLS)溶液中的能量转移进行了研究。当SLS浓度远低于它的cmc值时可明显地观察到两种染料间的能量转移, 说明在此浓度下SLS的预胶束已生成。以Ia/(Id+Ia)值表示两种染料分子间能量转移的效率, 在SLS浓度增长过程中, 存在着一个效率的极大值。当溶剂水中加入不同量的DMSO时, 发现效率极大值移向SLS的高浓度处。这一结果表明:分子间的疏水作用力是SLS分子形成预胶束的推动力。     

Coordination of methanol clusters to benzene: a computational study

Benzene-methanol cluster structures were investigated with theoretical chemistry methods to describe the microsolvation of benzene and the benzene-methanol azeotrope. Benzene-methanol (MeOH) clusters containing up to six methanol molecules have been calculated by ab initio [MP2/6-311++G(d,p)//MP2/6-31+G(d,p) + BSSE correction] method. The BSSE was found quite large with this basis set, hence, different extrapolation schemes in combination with the aug-cc-pVxZ basis sets have been used to estimate the complete basis set limit of the MP2 interaction energy [ΔE(MP2/CBS)]. For smaller clusters, n ≤ 3, DFT procedures (DFTB+, MPWB1K, M06-2X) have also been applied. Geometries obtained for these clusters by M06-2X and MP2 calculations are quite similar. Based on the MP2/CBS results, the most stable C(6)H(6)(MeOH)(3) cluster is characterized by a hydrogen bonded MeOH trimer chain interacting with benzene via π···H-O and O···H-C(benzene) hydrogen bonds. Larger benzene-MeOH clusters with n ≥ 4 consist of cyclic (MeOH)(n) subclusters interacting with benzene by dispersive forces, to be denoted by C(6)H(6) + (MeOH)(n). Interaction energies and cooperativity effects are discussed in comparison with methanol clusters. Besides MP2/CBS calculations, for selected larger clusters the M06-2X/6-311++G(d,p)//M06-2X/6-31+G(d,p) procedure including the BSSE correction was also used. Interaction energies obtained thereby are usually close to the MP2/CBS limit. To model the benzene-MeOH azeotrope, several structures for (C(6)H(6))(2)(MeOH)(3) clusters have been calculated. The most stable structures contain a tilted T-shaped benzene dimer interacting by π···H-O and O···H-C (benzene) hydrogen bonds with a (MeOH)(3) chain. A slightly less negative interaction energy results for a parallel displaced benzene sandwich dimer with a (MeOH)(3) chain atop of one of the benzene molecules.     

新型以若丹明染料为母体的三发色团化合物的荧光性能

若丹明染料作为一种重要的激光染料,它们具有较高的荧光量子效率。这类染料在紫外区的吸收是相当小的,于是,当它们被使用在横向泵浦激光装置上时,就需要相当高的染料浓度,这样才能有效地吸收紫外泵浦光(如XeCI激光器,308 nm)。问题是,这类染料的发射光谱与其吸收光谱的低能量部分有重叠,亦即它门的Stokes位移较小,并且由于染料的荧光量子效率通常小于100,以致使一部分染料的激发辐射被基态染料分子再吸收,从而导致激发辐射的损失。与此同时,为了有效吸收泵浦光能量,染料的浓度通常很高,这样,激发辐射损失就会相当大。     

Pyrene fluorescence at air/sodium dodecyl sulfate solution interface

The dependence of pyrene fluorescence spectra on the concentration of sodium dodecyl sulfate (SDS) was observed, where the solution was prepared from water saturated with pyrene. The values of the I(1)/I(3) ratio from the bulk solution and from the upper meniscus region in an optical cell were similar but decreased rapidly around the critical micelle concentration (cmc) of SDS, indicating that pyrene molecules preferred to be solubilized in the micelles having a lower dielectric constant. The fluorescence intensity of the excimer indicated the concentration of pyrene molecules at the air/solution interface or the surface activity of pyrene molecules. In addition, the intensity from the meniscus region is much larger than that from the bulk at the concentrations below the cmc, whereas there was no difference in the intensity between the bulk and the meniscus above 8 mmol dm(-3) of SDS. The analysis of the fluorescence intensity from the excimer strongly suggests the presence of molecular aggregates that are favorable to the pyrene molecules just like the micelles in the bulk, making them less movable.     

Time-resolved fluorescence spectroscopy of hematoporphyrin, mesoporphyrin, pheophorbide a and chlorin e6 in ethanol and aqueous solution

The fluorescence decay I(t) and time-resolved spectra I(lambda, t) of some porphyrins and chlorins in ethanol and phosphate-buffered aqueous solution were investigated with a time-correlated single-photon-counting apparatus with a mode-locked Ar+ laser (514.5 nm) as the excitation source. The fluorescence of hematoporphyrin, mesoporphyrin and pheophorbide aa is considerably influenced by the conditions of aggregation (these compounds undergo aggregation in phosphate-buffered solution but not in ethanolic solution). The fluorescence decay of chlorin e6 which remains monomeric in both solvents is single exponential in all cases. The fluorescence spectra of hematoporphyrin, mesoporphyrin and pheophorbide a in phosphate-buffered solution are shifted with respect to the spectra obtained in ethanol; moreover, a new emission band (X band) appears, whose intensity increases on increasing the amount of equilibrium aggregates and shows a fast fluorescence decay. For hematoporphyrin and mesoporphyrin the appearance of the X band emission appears to be correlated with irreversible photoprocesses leading to fluorescent photoproducts. Analysis of the reported fluorescence spectra of cancer cells after incubation with hematoporphyrin derivative suggests that the fluorescent photoproducts might be formed also in vivo.     

Spectroscopic study of Mentha oils

The visible fluorescence and excitation spectra of Mentha oils (Japanese mint oil, peppermint oil and spearmint oil) have been recorded. Different physical constants which are characteristic of the fluorescent molecules have been calculated for all three oils. Results reveal that the same group of organic compounds dominate in the oils of peppermint and spearmint, whereas some different compound is present in Japanese mint oil. It is also found that the fluorescence intensity of these oils is comparable to that of Rhodamine 6G dye in methanol solution. Our studies suggest that Mentha oils may be a useful lasing material in the 450–600 nm wavelength range.