单重态氧化学 VI: 胶束中竹红菌甲素诱导的二苯基异苯并呋喃光敏氧化反应动力学

本文研究了增溶于胶束内部的HA诱导的DPBF光敏氧化动力学。测定了DPBF在不同胶束中光敏氧化总速率常数, 分别为5.12×10^9(SDS), 2.31×10^9(Triton X-100)和6.21×10^9L/mol.s(TDPB)。实验证明胶束可有效猝灭单重态氧却不猝灭HA的激发三重态, 从而导致DPBF光敏氧化双分子反应可按假一级动力学规律处理, 可求出表观速率常数为1.52×10^-^3s^-^1(SDS)或1.54×10^-^3s^-^1(Triton X-100), 相应的半寿命为7.5min, 这些结果为HA在水溶液中的光动态行为的研究提供了依据。     

单重态氧化学 VI: 胶束中竹红菌甲素诱导的二苯基异苯并呋喃光敏氧化反应动力学

本文研究了增溶于胶束内部的HA诱导的DPBF光敏氧化动力学。测定了DPBF在不同胶束中光敏氧化总速率常数, 分别为5.12×10^9(SDS), 2.31×10^9(Triton X-100)和6.21×10^9L/mol.s(TDPB)。实验证明胶束可有效猝灭单重态氧却不猝灭HA的激发三重态, 从而导致DPBF光敏氧化双分子反应可按假一级动力学规律处理, 可求出表观速率常数为1.52×10^-^3s^-^1(SDS)或1.54×10^-^3s^-^1(Triton X-100), 相应的半寿命为7.5min, 这些结果为HA在水溶液中的光动态行为的研究提供了依据。     

单重态氧化学 Ⅵ.胶束中竹红菌甲素诱导的二苯基异苯并呋喃光敏氧化反应动力学

本文研究了增溶于胶束内部的HA诱导的DPBF光敏氧化动力学。测定了DPBF在不同胶束中光敏氧化总速率常数,分别为5.12×10~9(SDS),2.31×10~9(Triton X-100)和6.21×10~9L/mol·s(TDPB)。实验证明胶束可有效猝灭单重态氧却不猝灭HA的激发三重态,从而导致DPBF光敏氧化双分子反应可按假一级动力学规律处理,可求出表观速率常数为1.52×10~(-3)s~(-1)(SDS)或1.54×10~(-3)s~(-1)(Triton X-100),相应的半寿命为7.5min。这些结果为HA在水溶液中的光动态行为的研究提供了依据。     

十二醇聚乙二醇醚分子量分布与其溶液界面性能的关系

利用高纯单一十二醇聚乙二醇醚C₁₂E_n摸似配制Gauss分布型混合物,测定其水溶液的表面张力、增溶量及去污率。实验结果表明,聚乙二醇链长不同分布的醇醚混合物属于理想混合。混合溶液的Γ_∞、Πcmc 随分布宽度增加而增大。形成表面吸附膜及胶束时,短 EO 链分子占先。胶束溶液对乙苯的增溶量随分子中EO数增多而增大。宽分布C₁₂E_n的去污率优于窄分布,但在一定分布范围内,其影响不显著。     

竹红菌甲素光敏氧化反应机制

本文报道了在竹红菌甲素的光敏氧化反应中,原初反应产生了~1O_2、O_2~-和H_2O_2,在一些还原性底物(5-羟基色氨酸、色氨酸、组氨酸、蛋氨酸和赖氨酸等)的存在下,体系中形成的O_2~-量大大增加。证明了体系中的~1O_2是通过三重态的竹红菌甲素和基态氧进行能量传递形成的,O_2~-是体系中的竹红菌甲素负离子自由基和基态氧进行单电子转移的结果,H_2O_2是体系中存在的竹红菌甲素二价负离子还原基态氧的产物。在一些底物存在下,次级反应产生了·OH。我们也发现竹红菌甲素具有弱的抽氢能力而生成一些有机自由基,这些有机自由基的形成促进了各种活泼态氧的相互转化,因此我们认为竹红菌甲素的光敏氧化是各种活泼态氧和一些有机自由基综合反应的结果。     

竹红菌甲素在碱性和中性溶液中的结构变化

竹红菌甲素(简称甲素,HA)是从我国云南省的一种真菌——竹红菌中提取出来的主要光敏色素。竹红菌乙素(简称乙素,HB)是竹红菌中另一个比甲素少得多的光敏色素。甲素在酸性条件下可以转化成乙素,但产率不高。下面讨论甲素在碱性和中性溶液中的结构变化,提供从甲素制备乙素和I的简便方法。     

胆红素在胶束中的性质及其敏化光氧化反应

本工作研究了胆红素IX_x(BR)分子在阳离子和阴离子表面活性剂形成的胶束中的性质,以及胶束对竹红菌甲素(HA)敏化光氧化BR的影响。将BR溶在少量二甲基亚砜(DMSO)中,取一定量此溶液加入水中制成浓度为～10~(-5)     

均相和非均相体系中竹红菌甲素与尾孢素光敏活性的比较

本文在均相有机体系和非均相胶束体系中用ESR、自旋捕捉、消自旋等技术研究了竹红菌甲素(HA)和尾孢素(CP)的光敏特征;测量了其光动力作用过程中¹O₂、负离子自由基和O₂^·-的相对产率,发现均相体系中HA的光敏活性略高于CP。这表明侧环对醌类光敏剂的光敏活性影响不大。在非均相体系中由于胶束对HA激发态较强的保护作用,HA的光敏活性显著地强于CP。     

吲哚方酸菁染料在表面活性剂水溶液中的光降解

考察了4种含有不同N位取代基的对称吲哚方酸菁染料在阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)、阴离子表面活性剂十二烷基硫酸钠(SDS)和非离子表面活性剂曲拉通(TX-100)水溶液中的光降解行为,结果表明,表面活性剂对染料分子具有保护作用,其影响大小为CTAB>TX-100>SDS,分子中有羧基的染料受影响程度最大。在表面活性剂浓度较低时,染料光降解程度随着表面活性剂浓度的增加而增加,但形成胶束后,染料的光降解程度则随着表面活性剂浓度的升高而降低。     

激光光散射和电子自旋共振技术研究十二烷基硫酸钠与聚乙烯吡咯烷酮的相互作用

应用动态激光光散射(DLS)和电子自旋共振(ESR)测定研究了单长链表面活性剂十二烷基硫酸钠(SDS)与聚乙烯吡咯烷酮(PVP)相互作用.DLS测定结果表明:SDS在水中形成动力学半径约为61 nm的胶束聚集体,PVP在水中卷曲成动力学半径约为12 nm的线圈,DLS确定的SDS临界胶束浓度(cmc)为6.4×10^-3 mol·L^-1, PVP-SDS具有强的相互作用,PVP分子缠绕在SDS胶束聚集体的周围,屏蔽了SDS胶束聚集体表面碳氢基团与连续水相的接触;ESR结果表明:自由基探针5-doxyl stearic acid在SDS形成胶束聚集体后,从一个较强极性的连续相转变到较小极性的胶束聚集体内核中,胶束聚集体内核的微粘度较纯水的大,SDS与PVP复合聚集体的微观粘度较SDS胶束溶液的大,ESR确定SDS的cmc为6.8×10^-3 mol·L^-1.     

Diffusion Coefficients and Structure Properties of Triton X-100/ n-C6H13OH/H2O System

Abstract

The diffusion coefficients of Triton X-100 micelles with different shape are determined by cyclic voltammetry without any probe. The first CMC (3.2 × 10^?4 mol-L^minus;1) and the second CMC (1.3 × 10^minus;3 mol-L^minus;1) of Triton X-100 micelles arc obtained, and the mechanism of electrochemical reaction for Triton X-100 is deduced, When n-hexanol is added, the diffusion coefficient of Triton X-100 micelles with different shape increases, but the solubilization fraction of n-hexanol decreases in spherical micelles and is almost constant in rodlike ones. However, the micropolarity of micelles decreases in both spherical and rodlike micelles. Furthermore, the diffusion coefficient of Triton X-100 micelles with different shape increases with temperature and the diffusion activation energy increases with n-hexanol content.     

FLUORESCENCE PROBE FOR MICROENVIRONMENTS: A NEW PROBE FOR MICELLE SOLVENT PARAMETERS AND PREMICELLAR AGGREGATES

Abstract— A previous study on the electronic spectroscopy of p -N,N-dialkylaminobenzylidenemalononitrile, 1, has been extended to a larger variety of organic solvents and to micelles of ionic and nonionic surfactants. By comparing the fluorescence emission (λ_F and φ_∫) of 1 in micelles and in homogeneous organic solvents, the effective polarity and the microviscosity of the micellar environments of potassium dodecanoate, sodium dodecyl sulfate, cetyltrimethylammonium bromide and Triton X-100 micelles have been determined to be 40, 40, 36 and 28, respectively and 23, 31, 34 and 28 cP, respectively. These results indicate that the fluorescence probe is located in the micelle–water interface of a micelle and this region of a micelle is polar and viscous. 1 has also been studied in different surfactants with varying surfactant concentrations. The φ_∫ of 1, a microviscosity gauge for micellar aggregates, remains unchanged at the critical micelle concentrations of various surfactants, but decreases at much lower surfactant concentrations. This is attributable to the formation of premicellar aggregates of surfactant molecules below their critical micelle concentrations.     

THE PHOTOPHYSICAL PROPERTIES OF SOME C15 LUPINE ALKALOIDS:

Abstract Sparteine, the tetracyclic saturated amine alkaloid, is highly fluorescent in n-hexane solution (Φ_f= 0.64; ζ= 63 ns) and has a large Stokes shift [λ_max (abs) = 203 nm; λ_max (fluor) = 325 nm]. Its isomer, α-isosparteine, has similar properties: Φ_f= 0.55; ζ_f= 50 ns; λ_max (fluor) = 338 nm. Oxidized derivatives, such as lupanine, thermopsine, and α-diplospartyrine, are weakly fluorescent. Based on a comparison with spectroscopic and photophysical properties of the monoamine, quinolizidine, it is concluded that the excitation energy is delocalized over the two N-atoms in starteine and a-isosparteine. The self quenching rate constant for sparteine, ca. 1 times 10⁷M^-1 s^-1, is about 100 times smaller than that for quinolizidine, consistent with excited state derealization. The significant fluorescence quenching in lupanine is rationalized by the fact that N-methyl-2-piperidone mfe/molecularly quenches the fluorescence of quinolizidine at nearly the diffusion controlled rate in -hexane. Comparisons are made with the fluorescence properties of other diamines such as N, N'-dimethylbispidine and N, N'-disubstituted piperazines.     

Triton X-100/n-C~4H~9OH/H~2O体系的扩散系数与结构特性

在无外加探针条件下用循环伏安法测定了不同形状TritonX-100胶束的扩散系数,得到第一cmc(临界胶束浓度)为3.1×10^-^4mol.L^-^1,第二cmc为1.3×10^-^3mol.L^-^1,并给出了TritonX-100的电化学反应机理。随正丁醇含量的增加,TritonX-100球形胶束的扩散系数迅速增加,正丁醇的增溶分数略有降低,但胶束内微极性却降低较多;棒状胶束转变为球形胶束,正丁醇的增溶分数基本不变,但胶束内微极性降低。随温度升高,TritonX-100分子与胶束的扩散系数均增加。正丁醇含量<1.5%时,扩散活化能E~D随正丁醇含量增加而迅速增加;但正丁醇含量>1.5%时,E~D增加变缓。     

THE TRIPLET AND RADICAL SPECIES OF HAEMATOPORPHYRIN AND SOME OF ITS DERIVATIVES

Abstract— Nanosecond laser flash photolysis and pulse radiolysis have been used to generate and characterise the triplet state, and semioxidised and semireduced radicals of haematoporphyrin, and three 0 -acyl compounds derived from it (the monoacetate, the diacetate and the disuccinate).
After 347 nm irradiation in water containing 2% Triton X-100, haematoporphyrin forms the triplet state (φ_T= 0.92) and photoionises monophotonically (φ_I= 0.03). For the O -acyl derivatives, φ_T approaches unity and photoionisation is reduced. In acetone the triplet yield of all four compounds are close to unity. The difference and corrected spectra for the triplet species are presented and decay rates ( k ₁˜10⁴s^-1) and oxygen quenching constants ( k _Q˜1.5times10⁹ M ^-1s^-1) for the triplet state have been measured. The difference and corrected spectra for the semi-reduced species in methanol and semi-oxidised species in aqueous Triton X-100 are presented.
The photophysical characteristics in fluid solution of haematoporphyrin and its 0 -acyl derivatives are rather similar to those previously recorded for other photosensitising porphyrins.     

Dramatic persistence (minutes) of the triplet excited state and efficient singlet oxygen generation for C60 incorporated in Y zeolite and MCM-41 silicate

The triplet excited state of C₆₀ (λ_max=780 nm) lives minutes and can be monitored by conventional spectrophotometers when this fullerene is incorporated inside LiY, as opposed to C₆₀@HY and C₆₀@MCM-41 wherein C₆₀ triplet lives in the submillisecond time scale. C₆₀ adsorbed in LiY or MCM-41 efficiently generates ¹O₂ that was detected by its characteristic NIR emission (λ_em=1270 nm).     

TRANSIENT PHENOMENA IN THE PULSE RADIOLYSIS OF RETINYL POLYENES—7. RADICAL ANIONS OF VITAMIN A AND ITS DERIVATIVES

Abstract— Upon e^--pulse irradiation in nonprotic solvents, all- trans retinol (ROH) and retinylmethyl ether (ROMe) form transient species (τ= 0.5–7μs, λ_max=575–590 nm) identifiable as radical anions. Similar species are also formed upon laser pulse photoexcitation of these retinyl derivatives in the presence of N,N-dimethylaniline in acetonitrile. In contrast, electron transfer or attachment to all- trans retinyl acetate (ROAc) and palmitate (ROPa) results in 'instantaneous' loss of carboxylate anions from electron adducts giving the retinylmethyl radical (R-, λ_max= 395 nm, τ_k > 100 μ,s); the radical anions in these cases are too short-lived to be detected by nanosecond pulse radiolysis. The lifetimes of radical anions of ROH and ROMe are very sensitive to water and alcohols (e.g. k_q = 10⁷ M ^-1 s^-1 with methanol as quencher for ROH^- in tetrahydrofuran). Based on these findings, the spectral dissimilarity of the one-electron reduction products from ROH and ROAc in alcohols and aqueous micelles becomes explainable in terms of fast formation of protonated radical anions (RH(OH), τ_1/2, > 100 μs, λ_max=370–375 nm) in the case of ROH and of retinylmethyl radical via loss of AcO^- from radical anion in the case of ROAc. In tetrahydrofuran, the complexation of ROH^- with cations such as Na⁺ and Bu₄N⁺ affects the relative importance of its major decay modes, namely, protonation and dehydroxylation, the latter process being significantly enhanced by the presence of Na⁺.     

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.     

THE PHOTOCHEMICAL INTERACTION BETWEEN THE TRIPLET STATE OF 8-METHOXYPSORALEN AND THE MELANIN PRECURSORL–3, 4 DIHYDROXYPHENYLALANINE

Abstract— The photochemical interaction between 8-methoxypsoralen (8-MOP) and the melanin precursorL–3,4-dihydroxyphenylalanine(dopaH₂) has been studied using laser flash photolysis. Triplet excited 8-MOP was thus found to abstract electrons from dopaH₂ ( k ∼ 2 × 10⁹ dm³ mol^-1 s^-1) to form semireduced 8-MOP and semioxidised dopaH₂.The technique of pulse radiolysis was used to establish separately the spectra of (a) the semi-reduced form of 8-MOP at pH 6.5 and (b) the semioxidised forms of dopaH₂ at pH 6.5, 5.8, 4.6 and 3.3. The corresponding λ_max and extinction coefficients found were: for 8-MOP at pH 6.5, λ_max= 350 nm (= 9050 dm³ mol^-1 cm^-1); for dopa at pH 6.5, λ_max= 305 nm (ε= 12000 dm³ mol^-1 cm^-1) and for dopaH at pH 3.3, λ= 305 nm (ε= 5900 dm³ mol^-1 cm^-1).     

Photochemistry of dicyanopyridines

The photochemistry of a variety of dicyanopyridines (2,3-, 2,4-, 2,5-, 2,6-, 3,4- and 3,5-dicyanopyridine) in solution at room temperature was investigated. Pulsed UV (308 nm) laser irradiation in deoxygenated acetonitrile yields the triplet state with lifetimes between 4 and 10 μs and absorption bands in the 400 and 320 nm regions. In the presence of added HCl an air-insensitive transient (τ ≈ 10–12 μs, λ_max ≈ 360–380 nm) was observed, suggesting the formation of a protonated excited state.

Irradiation in the presence of amines resulted in the production of the pyridyl radical anion (τ ≈ 40–80 μs, air sensitive, λ_max ≈ 360–380 nm) formed by electron transfer from the amine to the pyridine triplet excited state. Stern-Volmer analysis gave electron transfer rate constants in the range (1–8) × 10⁻⁸ M⁻¹ s⁻¹.

In methanol solvent, irradiation yielded an air-insensitive transient assigned as the neutral pyridyl radical (τ ≈ 30–200 μs, λ_max ≈ 370–385 nm). The formation of these transients is discussed in the context of previous photochemical electron spin resonance and product studies.