卟啉酞菁模型化合物光致电子转移研究

本文采用时间相关单光子计数对卟啉酞菁ＴＴＰ－（ＣＨ２）ｎ－Ｐｃ模型化合物的光致电子转移进行了研究，发现激发Ｐｃ时，呈现单指数衰减，ｎ＝４时电子转移速率减小，活化能，重排能增加，电子转移效率下降，电子转移反应△ＧＣＳ与电荷分离活化络合物衰变速率ＫＣＴ，按以下规律：△Ｇ＾（５）ＣＳ〉△＾（３）ＣＳ〉△＾（４）ＣＳ〉△＾（２）ＣＳ，ｋ＾（２）ＣＳ〉ｋ＾（３）ＣＳ〉ｋ＾（４）ＣＳ〉ｋ＾（５）ｃｓ。其△Ｇ＾     

不同添加物对表面活性剂溶液预胶束形成的影响

关于表面活性剂溶液中预胶束的形成问题已有不少报道［’－‘］．预胶束是表面活性剂溶液在浓度很稀时（远小于其临界胶束浓度（CMC》、表面活性分子所形成的一种集合体·由于一般的物理化学方法对其难于捡出，因此常被研究者忽略．文献间曾指出：预胶束形成的驱动力与胶束一样，也是疏水作用所致．因此表面活性分子的链长、头部极性、溶剂性质以及添加物的引入等因素必然会影响预胶束的形成．本工作是对添加物的引入问题所作的初步研究·。作中所研究的阴离子表面活性剂有十二烷基硫酸钠（sss）·＋”烷基；Iv酸钠（5％）和十六烷基硫酸…     

桥链七甲川菁的合成及光性能

菁是一种具有多功能用途的染料,除用作卤化银感光材料及有机光导材料的光谱增感剂、光记录材料中记录介质外,还可作为染料激光器中用的激光染料.我们曾合成了四甲川苯乙烯菁、五甲川(艹粦)及五甲川吡喃鎓等红外染料作为激光染料,测定了它们的光性能.本文合成了具有桥链的七甲川菁,研究了这些桥链七甲川菁的吸收光谱及荧光光谱,并以YAG激光倍频(532nm)作泵浦源,测定了它们的激光调谐范围、中心波长及激光转换效率.     

Multicommutation as an environmentally friendly analytical tool in the hydride generation atomic fluorescence determination of tellurium in milk

The aim of this study is to show the advantages of the emerging multicommutation methodology based on the use of solenoid valves for Te determination in milk by hydride generation atomic fluorescence spectrometry (HG-AFS). The delivery of a series of alternating sequential insertions of small volumes of samples and reagents gives rise to new hydrodynamic processes and exciting analytical potentials by controlling the time of flow through the on/off-switched solenoid valves. This drastically reduces the reagent consumption by a factor of 4 and the generation of effluents (590 mL h^–1 instead of 750 mL h^–1 generated by the continuous-mode measurement) and also provides an improvement in the laboratory productivity by an increase of the sample throughput (85 h^–1 compared to 20 h^–1 found in the continuous mode). So, multicommutation is an environmentally and economically sustainable alternative to the methodology based on continuous measurements. The multicommutation-based method developed was applied to tellurium determination in commercially available milk samples; a calibration range of 0.0–0.5 ng mL^–1 and a detection limit of 0.20 ng L^–1 with average relative standard deviation of 2.1% were found. Comparable results were obtained for a series of samples using both continuous and multicommutation HG-AFS modes.     

Comparison of slurry sampling and microwave-assisted digestion for calcium, magnesium, iron, copper and zinc determination in fish tissue samples by flame atomic absorption spectrometry

The development of a slurry sampling method for the determination of calcium, copper, iron, magnesium and zinc in fish tissue samples by flame atomic absorption spectrometry is described. In comparison with microwave-assisted digestion, the proposed method is simple, requires short time and eliminates total sample dissolution before analysis. Suspension medium was optimized for each analyte to obtain quantitative recoveries from fish tissue samples without matrix interferences. Nevertheless, iron recoveries higher than 46% were not found. Treatment of samples slurried in nitric acid by microwave irradiation for 15-30 s at 75-285 W permitted to achieve efficient recoveries for calcium, iron, magnesium and zinc. Further improvement in the matrix effects for iron determination was accomplished by the use of an additional step of short microwave-assisted suspension treatment. However, standard addition method was required for calcium and copper determination, being necessary hydrochloric acid as suspension medium for the last one. Although copper could not be determined in the certified reference material using microwave-assisted digestion, the accuracy of the slurry sampling method was verified for all the investigated analytes. Detection limits were 22.8 ± 8.0, 0.884 ± 0.092, 5.07 ± 0.76, 35.5 ± 0.7 and 1.17 ± 0.04 μg g⁻¹ for calcium, copper, iron, magnesium and zinc, respectively. The standard deviations obtained using slurry sampling method and microwave-assisted digestion were not significantly different, and the mean relative standard deviation of the over-all method (n = 3) of the slurry sampling method for different concentration levels was below 12%.     

析相光度法测定铜（Ⅱ）的研究

本文研究了Ｃｕ（Ⅱ）－ＰＥＧ（聚乙二醇－２０００）－Ｚｉｎｃｏｎ（锌试剂）－（ＮＨ４）２ＳＯ４体系的析相光度法并应用于测定Ｃｕ（Ⅱ）。最宜酸度为ｐＨ５．５～８．５（ＫＨ２ＰＯ４－Ｋ２ＨＰＯ４）缓冲溶液）其络合物的最大吸收位于６１０ｎｍ，表观摩尔吸光系数为４．０×１０＾４Ｌ．ｍｏｌ＾－１．ｃｍ＾－１，Ｃｕ（Ⅱ）浓度在０～１．５ｍｇ／Ｌ范围内服从比尔定律，铜与Ｚｉｎｃｏｎ形式组成为１：２的稳定的蓝色络     

Photovoltaic and spectral properties of tetraphenyloporphyrin and metallotetraphenyloporphyrin dyes

Spectroscopical properties and photocurrent (or photovoltage) of tetraphenyloporphyrins and metallotetraphenyloporphyrins in nematic liquid crystal have been studied. Photoelectric response has been measured in an electrochemical cell made of the semitransparent semiconducting and golden electrodes with porphyrin dyes embedded in liquid crystal. Fluorescence, time-resolved luminescence in microsecond time scale and photoacoustic spectra have also been measured. The competition between radiative, non-radiative processes and charge transfer is discussed. It has been shown that effectivity of porphyrins for photocurrent generation depends on the presence/absence of central metal in the macrocycle of porphyrin skeleton and the kind of metal. The schematic model of the contributions of the dye molecule and semiconducting electrode in the electron transfer process is shown.     

POPOP诱导环糊精形成纳米管的研究

用紫外吸收光谱、稳态荧光、荧光各向异性和动态光散射等方法研究了2,2′-p-亚苯基-双(5-苯基噁唑) (POPOP)分子与环糊精(CD)的相互作用. 结果表明, POPOP分子在浓度较低时与β-CD形成1:2的包合物, 在浓度较高时可以进一步诱导β-CD形成纳米管结构. 同时发现, POPOP分子也可以诱导γ-CD形成纳米管结构. 对比于β-CD, POPOP分子在γ-CD水溶液中的荧光发射峰, 不仅有明显的红移而且也缺失了精细结构, 呈现较宽的大包峰. 这是由于POPOP分子成对进入γ-CD空腔形成了激基缔合物的缘故. pH和温度效应实验进一步表明, POPOP诱导β-CD形成的纳米管在pH大于12和温度高于331 K的环境下不能稳定存在.     

Spectrafluorimetric method for the rapid screening of toxic heavy metals in water samples

A fast and inexpensive sensitive screening test for recognising potential wastewater contamination by the presence of highly toxic heavy metals is described. The test is based on the reaction of the toxic heavy metals Hg(II), Cd(II), Pb(II) and Ag(I) with 6-mercaptopurine (6-MP) to produce highly fluorescent complexes.Optimum experimental conditions include a buffer of pH 7.2 (0.1 M citric acid/0.2 M Na₂HPO₄), a chelating reagent concentration of 6×10⁻⁴ M and the addition of 10⁻⁴ M of o-phenanthroline. The fluorescence emitted by the complexes was measured at 380 and 540 nm for excitation and emission wavelengths, respectively.Detection limits of 4, 3, 6 and 3 μg l⁻¹ were achieved for Hg, Cd, Pb and Ag. Relative standard deviation (R.S.D.) were between ±2 and ±6% of the fluorescence signals for five identical samples. Potential interference effects from other heavy metals (Zn, Mn, Co, Fe, Ni and Cu), which could affect the response of the proposed screening test was investigated. Results showed that none of these metals give rise to noticeable fluorescence signals under the above described experimental conditions.Finally, the capability of the proposed heavy metal screening test for the analysis of contaminated water samples is discussed.     

All-trans-N-retinylidenetryptamine Schiff base in surfactant solubilized water pools in heptane—a fluorescence study

All-trns-N-retinylidenetryptamine Schiff base was incorporated into aerosol-OT (AOT, sodium bis(2-ethylhexyl)sulphosuccinate)/heptane reverse micelles. This micellar system was used as a model to study the retinal-tryptophan interactions in retinal proteins. The retinylidene Schiff base remains stable in the presence of reverse micelle-solubilized water pools. Partition coefficient and microviscosity measurements show that the Schiff base is located in the micellar interphase. The results are discussed in terms of the interaction between the retinylidene chromophore and the active site environment of rhodopsin and bacteriorhodopsin. In the present model, the quencher and emitting units are covalently attached, and are separated by two carbon spacer units. The fluorescence emission data obtained for the micelle-intercalated Schiff base chromophore are compared with the fluorescence of the native protein and intermediates in the photochemical cycle of bacteriofhodopsin. A comparison of the data obtained for tryptamine and the Schiff base with the results available for bacteriorhodopsin and bacterioopsin reveals that there is a large degree of quenching on intercalation of the retinylidene chromophore in the vicinity of the fluorophore. Evidence provided by this model suggests that energy transfer to retinal can occur from tryptophan residues located in the retinal pocket in the native protein. Thus the retinylidene unit can act as a quencher of the energy of tryptophan, the nature and extent of which may depend on the conformation and relative orientation of the protein-bound fluorophore.