稀土元素共发光效应的研究——铕-钇-二苯甲酰甲烷-二苯胍-丙酮荧光体系及分析应用

本文详细研究了铕-钇-二苯甲酰甲烷(DBM)-二苯胍(DPG)-丙酮体系的共发光效应,在最佳实验条件下,Eu~(3+)在1.0×10~(-10)～5.0×10~(-8)mol/L浓度范围内与荧光强度成线性关系,检测限达5.0×10~(-13)mol/L。用多点增量标准加入法测定了合成样品中的铕结果满意。     

稀土元素悬浮液荧光体系的研究—铕—钆—二苯甲酰甲烷—二乙胺体系

系统研究了明胶对铕－钆－二苯甲酰甲烷－二乙胺沉淀悬浮液荧光体系的稳定化作用和钆对铕的荧光增强效应，使荧光强度提高约２个数量级，Ｅｕ的检出限达８．５×１０＾－１３ｍｏｌ／Ｌ（ｋ＝３），该体系可用于Ｇｄ２Ｏ３中痕量Ｅｕ的测定，结果满意。     

铕—钆—苯甲酰丙酮—邻—二氮菲共发光体系的研究

研究表明,在铕-苯甲酰丙酮-邻二氮菲体系中加入Gd^3 能使体系荧光强度大大增强,研究了铕-钆-苯甲酰丙酮-邻二氮菲共发光体系荧光度的影响因素,并利用该体系进行了稀土样品中Eu^3 的测定。     

稀土混合共发光效应的研究—（铽—钆—钇）—铕—噻吩甲酰三氟丙酮—氯化…

本文研究了铽（Ｔｂ）、钇（Ｙ）、钆（Ｇｄ）及它们的混合物对铕（Ｅｕ）－噻吩甲酰三氟丙酮（ＴＴＡ）－氯化甲基三烷基铵（Ｎ２６３）－Ｔｒｉｔｏｎ Ｘ－１００体系的共发光效应，发现稀土离子混合物的共发光效应具有线性加和性，用混合共发光体系不仅能保持单个稀土离子的共发光体系的增敏性，并经过实际樯品分析的验证，结果令人满意。     

稀土混合共发光效应的研究——(铽-钆-钇)-铕-噻吩甲酰三氟丙酮-氯化甲基三烷基铵-Triton X-100荧光体系

本文研究了铽(Tb)、钇(Y)、钆(Gd)及它们的混合物对铕(Eu)-噻吩甲酰三氟丙酮(TTA)-氯化甲基三烷基铵(N_(263))-Triton X-100体系的共发光效应,发现稀土离子混合物的共发光效应具有线性加和性,用混合共发光体系不仅能保持单个稀土离子的共发光体系的增敏性,而且抗干扰能力增强,并经过实际样品分析的验证,结果令人满意。     

稀土元素悬浮液荧光体系的研究——铕-钆-二本甲酰甲烷-二乙胺体系

系统研究了明胶对铕-钇-二苯甲酰甲烷-二乙胺沉淀悬浮液荧光体系的稳定化作用和钆对铕的荧光增强效应,使荧光强度提高约2个数量级,Eu的检出限达8.5×10~(-13)mol/L(k=3),该体系可用于Gd_2O_2中痕量Eu的测定,结果满意.     

Study of the Fluorescence Enhancement of Eu-Y-DEM-Dibenzoylmethane-Ammonia System

Abstract

The fluorescence enhancement and solvent effect of Eu-dibenzoylmethane-ammonia system was studied. The fluorescence intensity of the system can be greatly increased by y³⁺. The maximum fluorescence intensity was obtained at pH 8.9 – 9.5. The fluorescence intensity is a linear function of Eu²⁺ in the range of 1.0x10^?9 M -4.0x10^?8 M. The detection limit is 1.1x10^?10 M. The optimized procedure is applied to the determination of europium in lanthanide oxide samples.     

Solvent Effect on the Absorption and Fluorescence Emission Spectra of Some Purine Derivatives: Spectrofluorometric Quantitative Studies

The absorption and emission spectra of six purine derivatives: adenine (I), N(9)-hydroxyethyladenine (II), N(6)-acetyladenine (III), N(6)-isobutyryladenine (IV), guanine (V), and N(2),N(9)-diacetylguanine (VI) have been investigated. The effects of solvent and pH on the positions of λ _max (absorption) and λ _max (emission) of these compounds were determined. Correlations between the absorption wavelength (λ _max) of these organic compounds and the solvent parameters (D,n,E) or (K,M,N) show that the peak position is affected mainly by specific- and non-specific types of interactions between the solvent and solute. Solvent effects on the electronic absorption band shifts are indicative of the extent of charge reorganization of the solute molecules upon electronic excitation. The Stokes shift (ν _abs−ν _em) was correlated with the orientation polarizability (Δf) and was found to depend mainly on the dielectric constant and the refractive index of the solvents. This shift reflects the influence of the equilibrium solvent arrangement around the excited solute molecule, which rearranges inertially due to the instantaneous charge redistribution upon radiative deactivation to the electronic ground state. A spectrofluorometric analysis technique was applied for the quantitative analysis of the components of a ternary mixture of compounds (I–III).     

Studies on the Solvent Effect of N-Carbamoyl-N-(1-Oxyl 2,2,5,5-Tetramethyl-Pyrrolin-3-yl) Ureas

The electron spin resonance spectra of N-carbamoyl-N-(l-oxyl-2,2,5,5-tetramethyl-pyrrolin-3-yl) urea compounds in ten solvents with different polarities were determined. It was found that the hyperfine splitting constant AN and spin density pN. as well as the energy difference between two adjacent energy levels E of different pyrroline nitroxides in the same solvent increase with the increase of electron-withdrawing α-bility of the substituted groups on the aromatic ring. There was a linear correlation between AN and Reichardt ET value, and between AN and Z value as well. Such a linear correlation was also found between solvent viscosity n and ESR rotational correlation time r. On the other hand, the correlation between T and the relative height hr of peak on high field was reverse. The results are discussed in the paper.     

Kinetic Studies of Solvent and Pressure Effects on the Thermal Isomerization of Palladium Dithizonate

IntroductionThe photo-and thermo-chromisms of organometallic compounds have been intensivelystudied during thelast1 0 years.Meriwetheretal.[1 ,2 ] examined the chromic behaviorofmet-al-dithizone(phenyldiazenecarbothionic acid2 -phenylhydrazide) complexesin detail.From thekinetic and infrared studies,they showed thatthe central metal of a dithizonate complex de-termined the photochemical stability,the rate of the thermal return reaction,and the colorofthe dithizonate complex.As reported by Mer…     

Studies on the Fluorescence Enhancement Effect of Eu-La-DBM-DPG-Acetone System

The study of fluorescence enhancement has attracted attention recently. For example, the sensitivity and selectivity of Eu-thenoyltrifluoroacetone (TTA)phenan-throline and Eu-diphacinone-ammonia systems in Triton X-100 micelles are increased by the addition of La~(3+) Gd~(3+), Tb~(3+), Lu~(3+) or Y~(3+). The mechanism of this fluorescence(?)     

有机介质对2,3—二氨基吩嗪的荧光增敏作用研究

研究了有机介质对漆酶催化氧化邻苯二胺的产物－２，３－二氨基吩嗪（ＤＡＰ）的光谱性质的影响，结果表明，极性有机介质对其吸收光谱影响较小，但对其荧光具有强烈的增敏作用，荧光量子效率可提高近３０倍，据此，建立了有机介质增敏荧光测定ＤＡＰ的新方法，进一步研究表明：有机介质对２，３－二氨基吩嗪的荧光增敏原因在于其增溶作用，供电子效应及对ＤＡＰ分子吸收性能的增强。     

有机π共轭配体溶剂化效应与分子间相互作用的理论研究

采用可极化的连续介质模型(PCM), 运用密度泛函理论(DFT), 在B3LYP/6-31+G^**水平下研究了溶剂极性对有机π共轭配体N,N'-Bis-(3-pyridyl)ethylene-bis-urea(BPEBU)中syn-anti构象的分子几何和电子结构的影响, 并借助分子动力学模拟的方法, 采用明确溶剂模型研究了溶质-溶剂分子间的相互作用. 密度泛函理论计算结果表明, 随着溶剂极性的增强, BPEBU中尿素基上的CO键和N-H键以及吡啶环上的C-N键被明显极化, 使羰基氧原子和吡啶氮原子的电负性明显增强, 尿素基的N-H键上氢原子的正电荷也显著增加. 分子动力学模拟统计的结果表明, 在极性较强的乙醇溶液中, 有明确的O…H-O, N…H-O和N-H…O等3种氢键作用存在, 而在丙酮溶液中, 只有N…H-O一种氢键作用存在, 而且与乙醇溶液中的N…H-O作用相比要弱些. 另外, 采用密度泛函理论方法结合连续/明确的混合溶剂模型, 优化得到了溶质-溶剂三聚体的超分子簇结构, 与分子动力学模拟的第一溶剂层中的超分子结构相比, 两者定性一致.     

Determination of Iodide by Solvent Sublation Spectrophotometry

Abstract

The determination of trace iodide by preconcentration using solvent sublation and subsequent spectrophotometric measurements is described using cetyltrimethylammonium bromide (CTMAB) as a collector. the optimum conditions and the influence of diverse ions1 along with the wavelength of maximum absorption, concentration range and statistics of the method are presented. the method is applied to the iodide content in sea-water and results are compared with the iodide-starch method.     

Fluorescence Enhancement of Samarium－Thenoyl－trifluoroacetone－Cetyltrimethylammonium Bromide－Triton X－100 by Scandium

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冠醚增敏稀土配合物荧光增强效应的研究及其应用

本文详细研究了二苯并－１８冠－６对Ｓｍ－ＴＴＡ荧光体系的增敏作用和稀土离子Ｄｙ＾３＋对Ｓｍ－ＴＴＡ－冠醚体系的荧光增强效应，在冠醚存在下，Ｓｍ－ＴＴＡ二元配合物荧光体系的荧光强度增加了２８０倍，Ｓｍ－ＴＴＡ－二苯并－１８－冠－６体系中引入适量的Ｄｙ＾３＋后，使体系的荧光强度提高２６倍，对Ｓｍ－ＴＴＡ－冠醚和Ｓｍ－Ｄｙ－ＴＴＡ－冠醚体系，Ｓｍ的浓度分别在２．０×１０＾－７～１．０×１０＾－５ｍｏｌ／