敏化光解 盐的研究——蒽、芘、 电子转移荧光猝灭

本文采用稳态和瞬态光谱方法研究了四种二苯基碘 盐(Ph~2I^+X^-)对蒽、芘、 的激发态的猝灭作用, 通过Stern-Volmer方程确定了它们的光致电子转移速度常数。结果表明Ph~2I^+AsF^-~6对荧光猝灭是最有效的, 猝灭过程是扩散控制的。比较荧光强度和荧光寿命测定得到的猝灭常数, 表明猝灭是动态过程, 敏化剂与 盐间没有基态复合物生成。     

敏化光解螉盐的研究——蒽、芘、苝电子转移荧光猝灭

本文采用稳态和瞬态光谱方法研究了四种二苯基碘鎓盐(Ph_2I~+X~-)对蒽、芘、苝的激发态的猝灭作用,通过Stern-Volmer方程确定了它们的光致电子转移速度常数,结果表明Ph_2I~+AsF_6~-对荧光猝灭是最有效的,猝灭过程是扩散控制的。比较荧光强度和荧光寿命测定得到的猝灭常数,表明猝灭是动态过程,敏化剂与鎓盐间没有基态复合物生成。     

丝裂霉素C、阿霉素与过氧化氢酶的相互作用

用荧光光谱法研究了水溶液中抗癌药物丝裂霉素C、阿霉素与过氧化氢酶分子间的结合反应。结果表明：药物对过氧化氢酶的内源荧光有较强的猝灭作用，形成复合物所产生的静态猝灭是引起过氧化氢酶荧光猝灭的主要原因。进一步依据荧光猝灭结果确定了药物-酶复合物的形成常数。     

铜、锌离子对齐墩果酸与蛋白质相互作用的影响

使用荧光光谱和紫外吸收光谱研究金属离子存在下对齐墩果酸(OA)与牛血清白蛋白(BSA)相互作用的影响.实验结果表明,生理pH值条件下齐墩果酸对牛血清白蛋白的荧光猝灭可能是一个单一的静态猝灭过程.求得了OA与BSA相互作用的结合常数为6.16×103 L·mol-1.Zn2+或Gu2+存在下,OA对BSA的荧光猝灭类型没...     

荧光法研究金属离子对橙皮素与牛血清白蛋白相互作用的影响

采用荧光光谱和三维荧光光谱法研究了橙皮素(HSP)与牛血清白蛋白(BSA)之间的相互作用,并考察了共存金属离子Cu2+,Zn2+对二者相互作用的影响。实验结果表明,HSP对BSA的内源性荧光具有猝灭作用,猝灭类型为静态猝灭,作用力类型是氢键和范德华力,Cu2+,Zn2+的加入未改变HSP对BSA的猝灭类型和作用力类型。通过比较猝灭常数、结合常数、结合位点数、猝灭效率和三维荧光光谱图变化,推知Cu2+,Zn2+能与BSA产生结合作用,使其成为受制状态下的刚性肽链,从而影响HSP进入BSA疏水腔,减弱了HSP与BSA的结合能力,表现为与HSP存在竞争作用。     

几种金属离子对胭脂红与牛血清白蛋白相互作用的影响——荧光光谱研究

利用荧光光谱法研究了不同温度(15、27、39℃)下食用合成色素胭脂红对牛血清白蛋白(BSA)的内源荧光猝灭特性,考察了Cu2+、Ni 2+、Pb2+等金属离子对二者相互作用的影响,并测定了不同温度下的猝灭常数KSV、结合常数KA和结合位点数n.结果表明,3种金属离子基本不影响胭脂红对BSA荧光猝灭机理,但Cu2+、Ni 2+、Pb2+离子都与BSA有一定的结合能力,可在不同程度上增强胭脂红与BSA的结合作用及其对BSA内源荧光的猝灭.     

3种苯丙胺类药物与溶菌酶的作用机制及构效关系研究

在模拟人体生理条件下,采用荧光光谱法研究了3种不同结构的苯丙胺类药物(麻黄碱、伪麻黄碱和甲基麻黄碱)与溶菌酶之间的相互作用,计算了其结合常数、结合位点数和热力学参数,并探讨了3种药物对溶菌酶构象的影响.研究发现,三者可对溶菌酶内源性荧光产生强烈的猝灭作用,其猝灭过程均为静态猝灭.麻黄碱、伪麻黄碱和甲基麻黄碱与溶菌酶均形...     

荧光光谱法研究偶氮胂Ⅲ与牛血清白蛋白的相互作用

目的为了研究偶氮胂Ⅲ与牛血清白蛋白(BSA)在不同pH条件下(pH=2.0～9.0)的相互作用机理。方法采用荧光光谱法研究偶氮胂Ⅲ对BSA荧光的影响,通过计算获得作用机理的诸多信息。结果偶氮胂Ⅲ对BSA有较强的荧光猝灭作用,猝灭机制为生成复合物的静态猝灭;偶氮胂Ⅲ与BSA间的结合常数在pH 3.0～5.0最大,结合位点数为1;pH=3.5和4.5时偶氮胂Ⅲ与BSA色氨基酸残基间的结合距离在4.10 nm左右;两者主要靠静电引力结合;金属离子Mg2+、Ba2+和Ca2+对两者结合作用有影响。结论偶氮胂Ⅲ及偶氮胂Ⅲ-Ba2+、偶氮胂Ⅲ-Ca2+可作为优良的光谱探针,用于蛋白质的定量测定。     

荧光光谱法研究托拉塞米与牛血清白蛋白的相互作用及其分析应用

在pH 7.40和离子强度0.15 mol/L的模拟生理条件下, 托拉塞米(TOR)对牛血清白蛋白(BSA)的内源荧光产生较强的猝灭作用. 从吸收光谱的变化、温度对猝灭作用的影响及猝灭常数判断该猝灭作用是TOR与BSA形成基态配合物而导致的静态猝灭过程. 文中计算了TOR与BSA的结合常数K、结合位点数n和相关的热力学函数. 在最大猝灭波长342 nm处, 荧光猝灭程度(ΔF)与托拉塞米的浓度成正比, 线性范围和检出限分别为0.02～5.0 mg/mL和6.3 ng/mL. 本文还研究了适宜的反应条件, 考察了共存物质的影响, 表明方法具有较好的选择性, 据此提出了以BSA为探针快速测定痕量TOR的荧光光谱新方法, 适用于服用TOR后尿样和片剂中托拉塞米的测定.     

维生素B1与牛血清白蛋白的相互作用

采用荧光猝灭光谱、同步荧光光谱研究了维生素B1与牛血清白蛋白(bovine serum albumin,BSA)的相互作用机制.维生素B1对BSA 有较强的荧光猝灭作用,结合Stern-Volmer方程和热力学方程得到结合常数和对应温度下的热力学参数,并结合紫外吸收光谱进一步验证,维生素B1对BSA的猝灭过程为动态猝灭,二者主要以氢键和范德华力结合.并采用同步荧光光谱探讨了维生素B1对BSA 构象的影响.此外,讨论了共存Ca2+、Cu2+、Al3+、Mg2+ 和K+ 对维生素B1与BSA结合作用的影响.     

Fluorescence quenching of pyrene monomer and excimer by CH3I

The fluorescence quenching rate constants of pyrene monomer and excimer by CH₃I were obtained at several temperatures in methylcyclohexane. Both quenching processes are kinetically controlled, allowing insight on the mechanism of quenching. The rate constants have both temperature-independent and temperature-dependent components. The temperature-independent component for both monomer and excimer fluorescence is consistent with quenching due to enhanced intersystem crossing to a lower energy triplet state. The monomer temperature-dependent component comes from the enhancement of the intersystem crossing to a higher energy triplet state. The thermally activated excimer quenching is associated with the excimer dissociation step to give a pyrene in a second triplet state plus a ground state pyrene molecule.     

Dye induced quenching of firefly luciferase-luciferin bioluminescence

The quenching of firefly bioluminescence (BL) in presence of xanthene dyes and tetratolylporphyrin was investigated. The BL intensity was quenched with an altered decay pattern in presence of xanthene dyes and tetratolylporphyrin. The electronic absorption spectra indicate that there is no significant interaction occurring between the dyes and the BL components in the ground state. The BL quenching decay rate and fluorescence quenching studies of luciferin by the dyes suggest an energy transfer through an exciplex, involving oxyluciferin, in the excited state and the dyes, in the ground state. The bimolecular quenching rate constant (K(q)) values obtained from fluorescence studies varied between 7.7 x 10(12) and 19.8 x 10(12)M(-1)s(-1). The magnitude of the bimolecular quenching rate constants confirmed the complex formation between dye and excited oxyluciferin. The exciplex subsequently undergoes a non-radiative decay to the ground state via a combination of heavy atom induced and F?rster-type energy transfer. The decay rate constants in presence and in absence of dyes vary between 7.47 x 10(-4) and 7.6 x 10(-2)s(-1). In the presence of dyes the effective decay rate constants (k(eff)) increased while the lifetime of light emitting species decreased. The kinetic studies in presence of singlet oxygen scavengers, like beta-carotene and NaN(3), prove that there is no significant quenching of the firefly BL due to the formation of singlet oxygen.     

咔唑及其衍生物对 9-氰基蒽的荧光猝灭机理的研究

本文研究咔唑及其衍生物对9-氰基蒽(9CNA)的荧光猝灭机理。结果表明, 猝灭过程有以下三种方式:(1)一系列N-烷基咔唑及1,4-二咔唑丁烷、反式1,2-二咔唑环丁烷、N-苄基咔唑等对9CNA的荧光猝灭是通过形成激基复合物。(2)咔唑对9CNA的荧光猝灭是通过形成氢键。(3)1,3-二咔唑丙烷及N-痖烯基咔唑对9CNA的荧光猝灭是属于一般碰撞猝灭过程。以上所有猝灭过程主要都是来自电荷转移相互作用。另外, 还讨论了空间位阻对形成激基复合物的影响。并由稳态和动态荧光实验结果,应用Ware关于激基复合物的形成和解离的动力学公式计算出一系列光物理速率常数。     

Synthesis, characterization and theoretical analysis on a oxygen-sensing phosphorescent copper(I) complex

The fluorescence quenching of 9-aminoacridine by certain substituted uracils in water was studied using absorption, steady state and time resolved measurements. The bimolecular quenching rate constants (k_q), binding constant K and number of binding sites (n) were calculated based on the fluorescence quenching data. The free energy change (ΔG_et) for electron transfer process was calculated by Rehm–Weller equation. From lifetime measurement we observed that the quenching was mainly due to static mechanism involving ground state complex formation.     

Triplet state formation of aromatic hydrocarbons quenched with silver ion in ethanol

Fluorescence quenching rate constants of aromatic hydrocarbons by silver ions are determined. The values obtained are not well interpreted with thermodynamical considerations based on an electron transfer mechanism, but related to the intersystem crossing rate constant of the fluorescer. Triplet state formation in the course of quenching has been confirmed by laser photolysis studies.     

Carotenoid triplet state lifetimes

Carotene and xanthophyll triplet lifetimes are found to depend on the concentration of the parent molecule. These results account for some of the variations in carotenoid triplet lifetimes reported previously. The rate constants obtained for ground state quenching correlate with the number of conjugated double bonds, the longer chain systems having higher quenching rate constants.     

CHARGE TRANSFER COMPLEXES OF PHEOPHYTIN a WITH NITROAROMATICS. ELECTRON TRANSFER FROM EXCITED SINGLET OF PHEOPHYTIN a TO NITROAROMATICS

Abstract— The interaction of pheophytin a (Pheo) with seven nitroaromatic acceptors of varying ring sizes and electron acceptor abilities has been studied both in the ground and excited states. The ground state association constants ( K ) of the 1: 1 complexes of donor (Pheo) and acceptors were found to increase with increasing electron affinities of the different acceptors. All the nitroaromatic compounds efficiently quench the singlet emission of Pheo and the quenching follows the Stern-Volmer (SV) relationship. The SV constants ( K _sv) for different quenchers follow the same order as that of the K values. The reduction potential of Pheo₊/Pheo_* obtained from the quenching data agrees well with the theoretically predicted value. A charge transfer interaction between the singlet excited state of Pheo and the nitroaromatics is suggested from the dependence of quenching rate constants on the electron affinities of the acceptors.     

Effect of nickel complexing on the catalysis of nonradiative transitions in anthracene

By means of kinetic spectrophotometry we have studied the kinetics of the nonradiative deactivation of anthracene molecules in the triplet state in ethylene glycol at 25 C with nickel chloride and nickel ethylenediaminetetraacetate, cyclohexanediaminetetraacetate and diethylenetriaminepentaacetate complexes. Rate constants for the quenching of anthracene triplets by these compounds were determined. The ligands studied give the following series when ordered according to the strength of their quenching action: cyclohexanediaminetetraacetate相似文献   

The mechanism of riboflavin fluorescence quenching by nucleophiles

It is shown that the quenching of riboflavin (RF) fluorescence by nucleophiles, i.e., sulfite-, nitrite-, thiocyanate-, iodide-, and bromide ions, occurs by both a dynamic and static mechanism. The constants of quenching excited RF by anions and the constants of equilibrium of RF in the ground state and anions are determined. The formation of RF radicals in the presence of low concentrations of nucleophiles is revealed using flash photolysis.     

Dynamic photoluminescence studies of vanadium oxide anchored on SiO2 and the effects of added O2 and H2O

Dynamcc photoluminescence studies of V-ozide anchored onto SiO₂ are investigated in the absence and presence of O₂ or H₂O. It is found that the added O₂ molecules interact with the charge transfer excited triplet state of tetrahedrally coordinaeed V-oxide species. This results in an efficient quenching of the phosphorescence due to an enhanced radiationless deactivation. On the other hand, the added H₂O molecules interact with V-oxide in the ground state, resulting in the coordination change of V-species from tetrahedral to octahedral. These results obtained by dynamic photoluminescence spectroscopy are in good agreement with those obtained by ESR measurements of the photoreduced V⁴⁺ ions. From the Stern-Volmer plots for the quenching of the phosphorescence of V-oxide, the absolute quenching rate constants (reaction rate constants) of O₂ for the charge transfer excited triplet state of V-oxide anchored onto SiO₂ is first determined to be 3.2 × 10⁸ g-cat./mol s at 77 K and 9.3 × 10¹² g-cat./mol s at 298 K.