OPTICAL ABSORPTION AND EMISSION STUDIES ON LASER DYE INCORPORATED IN NAFION MEMBRANE

Abstract— Incorporation of the laser dye 7-amino-4-methyl coumarin (C-120) in a perfluoro sulfonate cation exchange membrane (Nafion) from aqueous solution has been studied by following its light absorption and emission (fluorescence) characteristics. It is shown that in the H⁺ form of the membrane the dye exists in its monoprotonated cationic form, whereas in different cation exchanged forms of the membrane it is incorporated as the unprotonated neutral molecules. By repeated equilibration with the aqueous solution, high concentrations of the dye could be loaded into the membrane. As compared to an aqueous solution, the polymer matrix was found to confer very good photostability to the dye.     

PHOTOPHYSICS OF DIOXORHENIUM(V) IN NAFION*

The emission properties of [ReO₂(py)₄]⁺ in Nafion perfluorosulfonated membranes have been investigated. The excited state of [ReO₂(py)₄]⁺is a sensitive probe of microheterogeneous environments in aqueous solution (Thorp el al. (1989) J. Am. Chem. SOC. 111 ,4364–4368). The absorption and emission maxima indicate that the interior of the membrane is quite polar, similar to ethylene glycol (Z-85). Two well-resolved emission components show different lifetimes (τ₁(H₂O) = 250 ns, τ₂,(H20) = 1.3 μs) and isotope effects (3.0, 2.4), indicative of varying degrees of solvent accessibility. The evidence suggests that [ReO₂(py)₄]⁺ occupies two distinct regions in the polymer film, assigned as the interfacial region and the ion-cluster region based on previous electrochemical studies involving other metal ions.     

一些新的芘衍生物的合成及光物理研究

本文合成了一系列新的芘衍生物，用紫外光谱和稳态荧光光谱方法研究了它们的光物理性质。结果表明，取代烷基几乎不影响芘的吸收光谱，而使芘的荧光光谱振动精细结构消失或部分消失；取代甲酰基的芘衍生物的荧光发射强烈依赖于溶剂的性质，极性溶剂中荧光光谱无精细结构，且荧光发射峰随介质极性的增加而红移。     

ZSM-5分子筛填充壳聚糖膜的制备与性能研究

采用液相共混的方法制备了ZSM-5分子筛填充壳聚糖膜.扫描电镜表征表明分子筛在膜中分散均匀,膜表面没有明显缺陷.考察了填充膜在碳酸二甲酯/甲醇混合液中的溶胀和吸附行为,探讨了填充膜中分子筛含量及操作温度对渗透汽化膜分离性能的影响.结果表明膜优先吸附甲醇,其分离性能主要由溶解过程控制;随着膜中分子筛含量的增加,膜的溶胀度增大,渗透通量大幅度提高;渗透通量与操作温度符合Arrhenius关系式.与壳聚糖均质膜相比,ZSM-5分子筛填充壳聚糖膜对甲醇和碳酸二甲酯混合物具有更好的分离效果.     

ON THE FORMATION OF PHOTOSYNTHETIC MEMBRANES IN BEAN PLANTS*

Abstract— The formation of lamellar chlorophyll-protein complexes I and II, solubilized by sodium dodecyl sulfate, was studied by hydroxylapatite column chromatography during greening of etiolated Phaseohis vulgaris leaves.
The protein moiety of both complexes preexists in the prolamellar body of etiolated tissue. The complex II to complex I protein ratio is of the order of 0.5. During greening in intermittent illumination the 'proto'-chloroplast is agranal, and contains 'primary' thylakoids and chlorophyll a (Chl a ). At this stage the complex II to complex I protein ratio increases only slightly. Further greening of the plant tissue in continuous illumination results in grana, Chi b (chlorophyll b ) and more Chl a formation. The complex II to complex I protein ratio in unfractionated thylakoids is now of the order of 2.5, while in grana it is of the order of 4.0.
The binding of chlorophyll formed during greening to the protein moiety of the two complexes is found to be selective. The Chi a selectively formed under intermittent illumination is more strongly bound to the complex I protein. The Chi b and Chl a formed in continuous illunination are found bound to both complex I and complex II proteins.
Analysis by hydroxylapatite column chromatography of subchloroplast fractions obtained by different fractionation procedures have shown that these two chlorophyll-protein complexes are most probably derived from the PSI (photosystem I) and PSII (photosystem II) particles of the photosynthetic membrane. These findings suggest that PSI units are assembled ahead of PSII units. Moreover, they indicate that the complex I protein is the main protein component in the prolamellar body membranes, the 'primary' thylakoids. and the stroma lamellae, while in the grana membranes the major protein is the complex II protein. Finally our results show that formation of the photosynthetic membranes is a multi-step process.     

PHOTOPHYSICAL STUDIES OF INDOLE ALKANOIC ACIDS and TRYPTAMINE IN REVERSE MICELLES OF SODIUM DIOCTYL SULFOSUCCINATE

Abstract— The fluorescence spectra and emission lifetimes of several 3-alkanoic indoles of different chain length and tryptamine (TA) were studied in sodium dioctyl sulfosuccinate (AOT)/heptane reverse micelles over a wide range of water/AOT ratio (R - 5 to 44). Fluorescence quenching experiments were done using carbon tetrachloride and acrylamide as quenchers. Experiments with TA were carried out using water at pH 3 in order to assure its protonation. Under these conditions, the results indicate that the indole moiety of TA remains at the micellar interface over all the range considered. Furthermore, the results can be interpreted assuming for the TA population a single microenvironment whose properties remain almost invariant when R increases from 11 to 44. The studies employing the 3-alkanoic indoles were carried out at pH 10. Under these conditions, the anions are progressively displaced to the water pool when the R value increases. This displacement is determined by the length of the side alkyl chain of the 3-indole derivatives. For these compounds, the quenching experiments indicate that, even at low R values, the excited indole moieties are distributed among different microenvironments.     

PHOTOPHYSICAL STUDIES ON THE BINDING OF TETRASULFONATOPHENYLPORPHYRIN TO LENS PROTEINS

Previous studies have shown that mesotetra(p-sulfonatophenyl)porphine (TPPS) binds to lens proteins. This characteristic should increase the residence time of the sensitizer in the lens and therefore enhance the probability of inducing photooxidative damage to that tissue in vivo. Subsequent in vivo studies have verified that contention. The present studies were performed to determine the effect of such binding on the spectroscopy and photophysics of the porphyrins. It was found that the binding of TPPS (1) quenches the fluorescence of lens proteins, (2) causes a shift in the ground state absorption spectra, fluorescence excitation spectra and the triplet excited state spectrum of TPPS to longer wavelengths and (3) results in an increase in the triplet state lifetime of TPPS. In the presence of the isolated crystallins the average triplet lifetime increases in the following order: gamma less than beta less than alpha.     

ZSM-5沸石膜内孔结构的研究

以正丁胺 (NBA)为模板剂、利用水热法在α -Al2 O3载体管上成功地合成了ZSM - 5沸石膜。对合成的沸石粉末及沸石膜进行热重分析 ,结果表明ZSM - 5沸石粉末孔道中的模板剂在 390℃和 550℃下分解最快。对膜在不同的焙烧温度下 ,单组份气体N2 、H2 、n -C4 H10 、i-C4 H10 的渗透通量进行了测量 ,结果表明在焙烧过程中 ,膜内主要有两种不同的孔产生 ,低温下晶间孔内的水份和模板剂首先逸出 ,这些孔对气体的选择性不大 ,但它们所占比例也不大。高温下沸石膜的晶内孔相继打开 ,膜的渗透选择性也随之提高。 60 0℃以后 ,膜内孔基本全部打开 ,膜对气体的理想选择性也达到最大。     

BILIRUBIN-PHOTOSENSITIZED LYSIS OF RESEALED ERYTHROCYTE MEMBRANES*

Abstract— The ability of bilirubin to photosensitize biomembrane damage has been tested, using resealed human erythrocyte ghosts as a model system. Continuous irradiation of bilirubin-charged ghosts with broad-band blue light resulted in membrane lysis, as evidenced by the release of trapped markers such as Na⁺ or glucose-6-phosphate. Sodium dodecyl sulfate-gel electrophoresis of membrane proteins revealed a progressive and relatively rapid loss of spectrin (bands 1 and 2) and band 4.1 during irradiation, accompanied by the appearance of cross-linked polypeptides. The antioxidant butylated hydroxytoluene protected ghosts against lysis, but not against protein cross-linking, suggesting that lipid peroxidation is the crucial membrane disrupting event.     

PHOTOPHYSICAL STUDIES ON HUMAN RETINAL LIPOFUSCIN

Fluorescent material generated in the human retina accumulates within lipofuscin granules of the retinal pigment epithelium (RPE) during aging. Its presence has been suggested to contributed to various diseases including age-related macular degeneration. Because this material absorbs light at wave lengths as long as 550 nm, photophysical studies were performed to determine whether lipofuscin could contribute to light damage and to determine if its composition is similar to a synthetically prepared lipofuscin. Time-resolved experiments were performed to monitor (1) fluorescence decay, (2) the UV-visible absorption of longer-lived excited states and (3) the formation and decay of singlet oxygen at 1270 nm. Steady-state and time-resolved fluorescence studies indicate that human and synthetic lipofuscin have fluorophores in common. Time-resolved absorption experiments on human retinal lipofuscin and synthetic lipofuscin showed the presence of at least two transient species, one absorbing at 430 nm (lifetime caμs) and a second absorbing at 580 nm, which decays via second order kinetics. In addition, there is a third absorbing species stable to several hundred milliseconds. The transient species at 430 nm is quenched by oxygen, suggesting that it is a triplet state. Subsequent studies showed the formation of singlet oxygen, which was monitored by its phosphorescence decay at 1270 nm. These studies demonstrate that lipofuscin can act as a sensitizer for the generation of reactive oxygen species that may contribute to the age-related decline of RPE function and blue light damage.     

ENERGETICS OF PHOTOPHYSICAL PROCESSES IN CHLOROPHYLL-LIKE MOLECULES

Abstract— The values of the absolute quantum yields of fluorescence and of intersystem crossing have been obtained for porphin and its derivatives by methods based on relative measurements involving flash photolysis. For a given compound the sum of these quantum yields is unity within experimental error which shows that the energetics of the molecules investigated is determined by competition of only two processes, viz., fluorescence and intersystem crossing, while internal conversion plays a negligible role. The values of the corresponding transition probabilities have been determined with the help of phase-fluorometric measurements. The dependence of the transition probabilities on molecular structure is discussed.     

TIME-RESOLVED SPECTROSCOPIC STUDIES ON PHOTOPHYSICAL PROPERTIES OF BENOXAPROFEN IN MICELLAR SOLUTIONS: AN INTRAMICELLAR FLUORESCENCE QUENCHING

The micellar dependencies of the photophysical properties of benoxaprofen (BXP), a 2-phenyl benzoxazole derivative, have been investigated using fluorescence spectroscopy and laser flash photolysis techniques. The fluorescence of BXP in aqueous solution has been observed to be remarkably quenched upon addition of a surfactant, cetyltrimethyl ammonium bromide (CTAB) or Triton X-100, in contrast to its enhancement in sodium dodecyl sulfate (SDS) micellar solution. Time-resolved fluorescence measurements show that the fluorescence decays biexponentially in the micellar solution, indicating the relaxation of micellar environments surrounding the excited BXP. The major component of fluorescence lifetimes in CTAB or Triton X-100 micellar phase is even shorter (330–427ps) than in SDS micellar phase (731 ps). The nonradiative decay constants are significantly larger (ca 3.0 times 10⁹ s^?1) in the CTAB or Triton X-100 micellar phase than in SDS micelles by a factor of ca 10. The major nonradiative decay is interpreted to be the internal conversion due to nuclear geometric change of BXP in the first excited singlet state. This is consistent with the observation that the quantum yields of intersystem crossing are very low (less than 0.01) in the micellar solutions as determined by the laser flash photolysis technique. The laser-induced transient absorption spectrum of BXP in CTAB or Triton X-100 micellar solution shows that the decay kinetics of the transients in CTAB or Triton X-100 are significantly different from first order kinetics in SDS.     

芘四硫酸四钠盐/甲基紫精复合物光物理性质的研究

本文通过吸收光谱滴定和时间分辨瞬态吸收光谱对芘四硫酸四钠盐(pyrenetetrasulfonic acid tetrasodium salt,PyTS)/甲基紫精(methylviologen,MV²⁺)复合物在水溶液中的光物理性质进行研究。用甲基紫精滴定芘四硫酸四钠盐时,得到该复合物的组成成份是1:1,反之,用芘四硫酸四钠盐滴定甲基紫精时,同样得到1:1组成成份的复合物。该复合物的形成常数是2.4×10⁶mol^-1·L,当用光激发该复合物时,发现其中存在芘四硫酸四钠盐到甲基紫精的电子转移过程,并得到该过程的动力学模型。     

PHOTOPHYSICAL BEHAVIOUR OF 5-METHOXYPSORALEN IN DIOXANE-WATER MIXTURES

Abstract— Triplet-triplet absorption spectra, intersystem crossing quantum yields, fluorescence lifetimes, and fluorescence quantum yields of 5-methoxypsoralen (5MOP) in dioxane-water mixtures are reported. The fluorescence and triplet formation quantum yields depend strongly on the water content in the mixtures, increasing up to maximum values which are, respectively, twentyfold and fivefold larger than in dioxane and then decreasing. This behaviour is essentially due to the variation of the internal conversion rate constant. With these solvent mixtures it is possible to emulate the dielectric response of 5MOP photophysical parameters in other media, such as in biological model systems and in human blood lipoproteins. The biological importance of these results is discussed.     

THE PHOTOPHYSICAL PROPERTIES OF PORPHYCENES: POTENTIAL PHOTODYNAMIC THERAPY AGENTS*

Porphycene and a tetra-n-propyl derivative remained unaltered on irradiation in toluene at room temperature. Quantum yields of fluorescence, S T intersystem crossing, and singlet molecular oxygen sensitization, as well as lifetimes of the singlet and triplet excited states were measured. In view of their structural relationship to porphyrin, their high absorption above 620 nm, their stability towards photooxidation, and their high quantum yields of fluorescence and singlet oxygen sensitization, these compounds qualify as potential agents for tumor marking and photodynamic therapy.     

芘—苯甲醛COPNA树脂的合成及其磁性行为的研究

芘苯甲醛ＣＯＰＮＡ树脂的合成及其磁性行为的研究阮湘泉董奕郑嘉明郭崇涛（天津大学化学工程系，天津３０００７２）关键词三芳基甲烷，ＣＯＰＮＡ树脂，稳定自由基，铁磁性在有机磁体的研究中，Ｏｔａ等人曾研究了以次甲基交联的缩合多核芳香烃（ＣＯＰＮＡ）树脂经光...     

全氟辛酸盐胶束对芘的加溶研究

胶束微观极性与微观粘度等微环境性质的研究近来已引起人们越来越广泛的注意。已有的研究工作主要限于碳氢表面活性剂体系,全氟表面活性剂体系的研究为数甚少。通常认为全氟表面活性剂有疏油性,因而对于全氟表面活性剂胶束能否加溶碳氢有机物,加溶部位胶束微环境性质如何,各种利用有机探针分子的光物理方法能否用于全氟胶束的物理化学性质的研究等问题很少有研究工作报道。本文研究了全氟辛酸盐胶束加溶芘的特性。实验     

在胶束中竹红菌甲素的光物理特性

研究了竹红菌甲素在胶束水溶液中的增溶能力及其光物理特性。实验证明,竹红菌甲素可以增溶于非离子型(TX-100),阳离子型(TDPB)和阴离子型(SDS)胶束水溶液中,增溶能力的顺序为:TX-100>TDPB>SDS。观察到在胶束中竹红菌甲素的两种互变异构体比例变化,在TDPB胶束中在高居占度条件下生成了基态相迂复合物,吸收峰位λ_max630nm,其对应的激基缔合物在荧光谱中出现在λ_max670nm处。     

DEACTIVATION OF PYRENE BY INDOLE IN MICELLAR SOLUTIONS

Abstract— The deactivation rate of excited pyrene by indole strongly depends on the polarity of the media. In micellar systems (Triton X-100, cetyltrimcthylammonium chloride (CTAC) and sodium dodecylsulfate (SDS) the deactivation efficiency is enhanced due to the high local concentration of indole in the micellar pseudophase. Quantitative interpretation of the data in CTAC and SDS micelles requires to take into account indole exchange between the micelles and the aqueous phase. In SDS micelles, where due to their smaller size the exchange process is more relevant, the exit and entrance rates are (3.0 ± 0.6) x 10⁶ and (1.2 ± 0.3) x 10¹⁰ M ⁻¹s⁻¹ respectively. Intramicellar bimolecular quenching constants are (1.1 ± 0.2) x 10⁸ M⁻¹ s⁻¹ (1.4 ± 0.2) x 10⁸ M ⁻¹ s⁻¹ and (1.5 ± 0.2) x 10⁸ M ⁻¹ s⁻¹ in Triton X-100, SDS and CTAC respectively. These rates are similar to those measured in ethanol rich ethanol-water homogeneous solutions. This is in agreement with the average polarity sensed by both pyrene and indole in the micellar pseudophases.     

FLUORESCENCE LINE-NARROWING STUDIES OF ANTIBODY-BENZO[a]PYRENE TETROL COMPLEXES

Benzo[ a ]pyrene tetrol (BPT) was used as a fluorescent probe to investigate the nature of antigen binding by two different monoclonal antibodies (MAb) that recognize a variety of derivatives of anti -7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[ a ]pyrenes (BPDE). Fluorescence line-narrowed spectra of the physical complexes of BPT formed with antibodies 8E11 and 3C3 were recorded at 4 K by employing vibronic excitation into the S, electronic state. The frequencies of the vibrational modes of the S₁ state were only marginally affected, though changes in relative intensities of some bands were observed. Fluorescence spectra recorded at 77 K by excitation into the S₂ state showed that the (0,0) fluorescence emission of BPT was shifted to red on complex formation. Intensity ratios of the (0,0) band and the main vibrational band at 1300 cm^-1 were used to assess the degree of interior binding of the chromophore. Quenching studies with acrylamide were employed to designate the complexes as type I, solvent inaccessible, or type II, solvent accessible. These studies also indicated that antibody 3C3 complexes tend to be more heterogeneous compared to the 8E11 complex. Deuterated BPT-d-12 also formed complexes with both antibodies, however, with different quenching behavior.