硝酮化合物对9-氰蒽荧光猝灭作用的研究

本工作对硝酮化合物猝灭9-氰蒽荧光的机制进行了研究,发现不同的9-氰蒽/硝酮体系可能经历包括电子转移、能量转移及竞争吸收等不同的猝灭过程。其中α,N-二苯基硝酮对荧光猝灭遵循电子转移机制,分别形成猝灭剂和敏化剂的离子自由基,但硝酮正离子自由基不能导致环化反应发生,结果还表明：硝酮化合物的四π电子1,3偶极结构在猝灭过程中起主要作用,因此当光环化反应破环1,3偶极结构生成氧氮丙啶时,即失去其原有的猝灭能力,导致已被猝灭的荧光重新回复。     

5-BrSAF-盐酸头孢他美酯荧光体系的研究及分析应用

在p H 7.40的磷酸盐(PBS)缓冲溶液中,盐酸头孢他美酯(CPH)可使5-溴水杨基荧光酮(5-Br SAF)的内源性荧光显著猝灭,据此建立了荧光猝灭法测定CPH的新方法。CPH的浓度在8.0×10-10~1.8×10-8mol/L范围内与体系的荧光猝灭值△F呈良好的线性关系,方法检出限为3.8×10-10mol/L,相对标准偏差为1.8%(n=5,c=8.0×10-9mol/L)。方法用于样品中CPH的测定,回收率为98.0%~103.5%。对体系的猝灭机理进行了研究,通过测定荧光寿命、探讨温度对猝灭常数的影响以及紫外吸收光谱的变化,确定CPH与5-Br SAF之间的猝灭过程为静态猝灭。     

某些芳香族氨基酸作探针荧光猝灭法测定安乃近及其代谢产物

在pH3.2的缓冲介质中,安乃近(ANG)及其代谢产物4-甲氨基安替比林(MAA)、4-乙酰氨基安替比林(AAA)与色氨酸(Trp)、酪氨酸(Tyr)和苯丙氨酸(Phe)等芳香族氨基酸反应并形成结合产物,引起上述氨基酸的荧光发生猝灭,最大猝灭波长分别位于352nm(ANG-Trp体系)、304nm(ANG-Tyr,MAA-Tyr和AAA-Tyr体系)和284nm(ANG-Phe体系).其荧光猝灭值(ΔF)在一定范围内与ANG,MAA和AAA成正比.荧光猝灭反应具有较高灵敏度,对于ANG,MAA和AAA的检出限为13.3ng/mL(ANG-Trp体系)、15.8ng/mL(ANG-Tyr体系)、64.5ng/mL(ANG-Phe体系)、150.0ng/mL(MAA-Tyr体系)和230.8ng/mL(AAA-Tyr体系).实验研究了荧光猝灭反应的适宜条件和影响因素,考察了共存物质的影响,表明方法具有良好的选择性,可用于ANG片剂及其代谢物尿药浓度的快速测定.从吸收光谱的变化、温度的影响以及Stern-Volmer作图,判断该反应为静态猝灭反应,氨基酸和安乃近通过静电引力和芳基堆积作用而形成1:1的复合物.     

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。     

氨基黑10B与牛血清白蛋白作用的光谱法研究

用紫外、荧光、圆二色光谱法研究了氨基黑10B与牛血清白蛋白(BSA)结合反应的光谱特性.结果表明氨基黑10B对牛血清白蛋白的荧光有猝灭作用,其猝灭类型属于静态猝灭;得到了不同温度下的结合常数和结合位点数;利用Gibbs-Helmholtz方程计算得到该猝灭反应的热力学参数,表明氨基黑10B主要以氢键和范德华力与BSA相互作用;圆二色和同步荧光光谱显示氨基黑10B对BSA构象产生了影响.     

新型水溶性萘啶基荧光材料的制备及性能研究

本文制备得到一种新型萘啶基的水溶性光致发光聚合物:聚丙烯酸(PAA)-2-苄氨基-7-甲基-1,8-萘啶,PAA₅-PAMN₂(PAMN是2-phenmethy-lamino-7-methyl-1,8-naphthyridine的缩写),经光谱分析和密度泛函理论计算,研究了化合物的结构和组成.这种聚合物在酸性和碱性条件下呈现最大的吸收波长分别为364和342 nm.Zn(OAc)₂的加入致使PAA₅-PAMN₂水溶液的荧光猝灭,而当OAc^-改变为NO₃^-时,在荧光强度不断降低的同时,由于NO₃^-离子的配位使最大发射波长从410 nm蓝移到400 nm.Na⁺+离子对其没有明显的荧光猝灭效应.     

吡喃并[3,2-c]吡啶-5-酮衍生物与血清白蛋白相互作用的光谱和分子对接研究

通过荧光光谱和紫外-可见吸收光谱法,在模拟生理条件下,研究了吡喃并[3,2-c]吡啶-5-酮衍生物-2-氨基-7-甲基-3-氰基-4-(4-甲苯)-吡喃并[3,2-c]吡啶-5-酮(AMP)与牛血清白蛋白(BSA)的相互作用。探讨了AMP对BSA的荧光猝灭过程的猝灭机理。不同温度下的Stern-Volmer曲线和紫外-可见吸收光谱表明:该衍生物主要以静态猝灭的方式使牛血清白蛋白的荧光猝灭。热力学参数表明两者之间的作用力类型主要为疏水作用力。用同步荧光技术考察了这一衍生物对牛血清白蛋白构象的影响。分子对接表明,该衍生物可能位于白蛋白的疏水腔IIA处。     

4-甲氧基-N-(4-(3-吗啉基丙氧基)苯基)-3-(4-(吡啶-3-基)嘧啶-2-基氨基)苯甲酰胺与人血清白蛋白的相互作用研究

应用分子对接模拟技术结合荧光猝灭法、同步荧光法、三维荧光法和紫外-可见光谱法,模拟生理条件(p H 7.4),在298 K和310 K温度下,研究了人血清白蛋白(HSA)与4-甲氧基-N-(4-(3-吗啉基丙氧基)苯基)-3-(4-(吡啶-3-基)嘧啶-2-基氨基)苯甲酰胺(1z)之间的相互作用。发现1z的加入引起了HSA内源荧光的静态猝灭,蛋白构象发生改变。理论研究与实验结果相结合研究了蛋白与药物的作用机理,从而为进一步寻找治疗慢性粒细胞白血病的药物小分子提供了实验依据。     

光谱法研究9-甲氧基喜树碱与BSA的相互作用

本文用吸收、荧光、圆二色等光谱法研究了9-甲氧基喜树碱(9-MCPT)与BSA的相互作用。随着9-MCPT的导入,BSA的吸收光谱发生位移,BSA的荧光发生猝灭并使荧光发射峰蓝移,说明9-MCPT与BSA发生了相互作用,且其产物是复合物。298K下体系的猝灭常数、结合常数和结合位点数分别为9.550×10~(4 )L·mol~(-1)、2.589×10~(4 )L·mol~(-1)和0.8949;并且猝灭常数随温度升高而减小,表明9-MCPT以静态方式猝灭BSA的荧光、结合比为1∶1。该体系的ΔH和ΔS均为负值,分别为-5.791 KJ·mol~(-1)、-2.636 J·mol~(-1)·K~(-1),说明BSA与9-MCPT的结合主要是氢键和范德华力所使,ΔG0表明9-MCPT自发与BSA发生作用。同步荧光光谱数据显示,9-MCPT接近BSA中酪氨酸残基。位点竞争实验显示9-MCPT-BSA的结合位点处于在BSAⅡA亚域内的SiteⅠ位点上。CD光谱中BSA的α-螺旋结构比例减少、β-折叠比例增加,表明9-MCPT改变了BSA的二级结构。     

光谱法研究萘酰亚胺类衍生物与牛血清白蛋白的相互作用

采用荧光光谱、紫外-可见吸收光谱、红外光谱和圆二色光谱研究了3-氨基-4-二甲氨基-N-丁基-1.8-萘酰亚胺(ADBN)与牛血清白蛋白(BSA)结合反应的特征。荧光光谱与紫外-可见吸收光谱表明,ADBN使BSA荧光猝灭的机理为静态猝灭。根据热力学参数判断ADBN与BSA主要是通过氢键和范德华力结合,结合距离为4.08 nm。同步荧光光谱、圆二色光谱以及红外光谱表明,结合过程中BSA的构象发生了变化。     

PHOTOINDUCED ELECTRON TRANSFER I.INTER-AND INTRAMOLECULAR QUENCHING OF ZINC PHTHALOCYANINE FLUORESCENCE BY ANTHRAQUINONE

Inter-and intramolecular quenching of zinc phthalocyaninefluorescence by anthraquinone has been studied.The diminutions offluorescence quantum yield and life-time are due primarily to electrontransfer.Apparent electron transfer rate constants were calculateddepending on the chain length and solvent polarity.     

一种新型的可见光诱导电子转移生酸体系的研究

对 4种分子内共轭的电荷转移化合物和取代的双 (三氯甲基 ) 2 ,4,6 三嗪分子间的光诱导电子转移和光生酸反应进行了详细研究 .通过荧光猝灭和体系荧光随时间的变化可看到作为电子受体的三嗪分子和作为电子给体电荷转移化合物间的光诱导电荷转移作用 .在对体系酸度的测定中 ,可清楚地看到体系经光照后所发生的变化 .对所研究生酸体系引发酚醛树脂 六甲氧基甲基三聚氰胺交联反应的能力进行了初步研究 .对可能发生的反应机制进行了讨论     

1,3,5-三芳基-2-吡唑啉化合物光物理行为的研究

合成了一组带不同取代基的三芳基吡唑啉化合物,对它们在不同极性溶剂中的光物理行为(如荧光量子产率,荧光寿命等)进行了测定指出:这类化合物在光的激发下除存在有分子内共轭条件下的电荷转移行为外,还存在着分子内非共轭条件下的电子转移,本工作还以三芳基吡唑啉化合物为猝灭剂对氧鎓盐的荧光猝灭能力进行了研究,并对所得结果作了讨论。     

Fluorescence Quenching of Poly[2-methoxy-5-(2''''-ethylhexoxy)-p-phenylene vinylene](MEH-PPV) in Solutions

Introduction Poly(1,4-phenylene vinylene) (PPV) has been the subject of explosive interest in these years. It has poten-tial applications in light-emitting diode, light emitting electrochemical cell and plastic laser.1-4 To improve its solubility and optical properties substituents are intro-duced to the PPV main chain. Poly[2-methoxy-5-(2'-ethylhexoxy)-p-phenylene vinylene] (MEH-PPV) is one of derivatives with alkoxy groups on phenyl rings. It exhibits superior solubility in organic sol…     

THE ROLE OF GROUND STATE COMPLEXATION IN THE ELECTRON TRANSFER QUENCHING OF METHYLENE BLUE FLUORESCENCE BY PURINE NUCLEOTIDES

The effect of three purine nucleotides on the fluorescence of methylene blue in aqueous buffer has been investigated. Guanosine-5'-monophosphate (GMP) and xanthosine-5'-monophosphate cause fluorescence quenching while adenosine-5'-monophosphate causes a red shift in the fluorescence maximum. All three nucleotides form ground state complexes with the nucleotides as indicated by absorption spectroscopy. The fluorescence changes at nucleotide concentrations less than 30 mM are best described by a static mechanism involving the formation of non-fluorescent binary and ternary complexes in competition with dimerization of the dye. Quenching of the fluorescence decay (tau = 368 ps) at high GMP concentrations (10-100 mM) occurs at the rate of diffusion. The mechanism of fluorescence quenching may involve electron transfer within the singlet excited dye-nucleotide complex although published values of the oxidation potentials of various purine derivatives would suggest that all three nucleotides should cause quenching. Evidence for electron transfer was obtained from flash photolysis experiments in which 100 mM GMP was found to cause the appearance of a long lived transient species absorbing in the region expected for semimethylene blue.     

2-芳基苯并噁唑的荧光猝灭和光诱导电子转移研究

本工作对两种不同的2-芳基苯并 唑化合物溶液荧光被四氯化碳所猝灭的机理进行了详细研究,通过多种途径研究表明该猝灭过程具有光诱导电子转移性质,工作还利用此电子转移所形成的活泼自由基来引发烯类单体的聚合,得到了有一定聚合度的聚甲基丙烯酸甲酯。     

Photo-induced intermolecular electron transfer from electron donating solvents to Coumarin dyes in bile salt aggregates: role of diffusion in electron transfer reaction

The photo-induced electron transfer between Coumarin dyes and aromatic amines has been investigated using steady state and time-resolved fluorescence quenching studies. We have observed a Marcus type inversion in the electron transfer rate in correlation of quenching constant to the free energy change occurred during reaction. To justify the "inverted region" obtained in the correlation of quenching constant versus free energy curve, we have performed anisotropy measurement and estimated the several diffusional parameters. The translational diffusion coefficients exhibit a similar picture like electron transfer rate constant when it is plotted against free energy. Thus we argued that the diffusion has played an important role in the electron transfer kinetics.     

Photoinduced electron transfer in a protein-surfactant complex: probing the interaction of SDS with BSA

Photoinduced fluorescence quenching electron transfer from N,N-dimethyl aniline to different 7-amino coumarin dyes has been investigated in sodium dodecyl sulfate (SDS) micelles and in bovine serum albumin (BSA)-SDS protein-surfactant complexes using steady state and picosecond time resolved fluorescence spectroscopy. The electron transfer rate has been found to be slower in BSA-SDS protein-surfactant complexes compared to that in SDS micelles. This observation has been explained with the help of the "necklace-and-bead" structure formed by the protein-surfactant complex due to coiling of protein molecules around the micelles. In the correlation of free energy change to the fluorescence quenching electron transfer rate, we have observed that coumarin 151 deviates from the normal Marcus region, showing retardation in the electron transfer rate at higher negative free energy region. We endeavored to establish that the retardation in the fluorescence quenching electron transfer rate for coumarin 151 at higher free energy region is a result of slower rotational relaxation and slower translational diffusion of coumarin 151 (C-151) compared to its analogues coumarin 152 and coumarin 481 in micelles and in protein-surfactant complexes. The slower rotational relaxation and translational diffusion of C-151 are supposed to be arising from the different location of coumarin 151 compared to coumarin 152 and coumarin 481.     

Fluorescence Quenching of Poly[2-methoxy-5-（2′-ethylhexoxy）-p-phenylene vinylene] （MEH-PPV） in Solutions

Fluorescence quenching processes of poly[2-methoxy-5-(2‘ethyl-hexoxy)-p-phenylene vinylene] (MEH-PPV) in solution by electron acceptors, O2 and acid, have been studied. Static quenching of the fluorescence from MEH-PPV by an electron acceptor (DDQ or TCNE) occurs due to electron transfer from MEH-PPV to the electron acceptor and this electron transfer quenching can be promoted by chloroform. Photooxidation takes place in the MEH-PPV solution and singlet oxygen is an intermediate in the photooxidation, according to the results of ESR spectroscopy. Acid also plays an important role in the fluorescence quenching process of MEH-PPV, by the protonation of the alkoxy groups in the molecular chain.     

FREE ENERGY DEPENDENCE OF THE QUENCHING OF CHLOROPHYLL a FLUORESCENCE BY SUBSTITUTED QUINONES*

The quenching of chlorophyll a (Chl a) fluorescence hy a series of substituted benzoquinones. naphthoquinones and anthraquinones has been examined employing ethanol and acetonitrile as solvents. All quinones are good quenchers of fluorescence. There is an excellent linear relation between the Stern-Volmer quenching constants, K, and the polarographic half wave potentials (E₁₂) of the quinones, with more oxidizing quinones being better quenchers. The quenching data are consistent with the excited state half wave potential of ?1.31 eV predicted theoretically, demonstrating that the kinetically estimated value of the Chl a excited state reduction potential agrees with that expected on spectroscopic grounds. The results of quenching are not in agreement with the conventional Marcus theory of electron-transfer reactions, as there is no evidence of quenching constant. K_q. decrease vsΔG⁰ even for free energy changes nearly twice that expected for the onset of the Marcus inverted region. However, the kinetically estimated K_q values are in good agreement with the ones calculated by using the Rehm and Weller equation for fluorescence quenching by electron transfer. Our experimental results support the electron transfer mechanism of quenching proposed by Seely.