喹喔啉衍生物与缺电子烯烃的激光闪光光解研究

利用时间分辨激光诱导瞬态吸收光谱装置,以一台Nd：YAG激光器四倍频后的266nm激光作为激发光源,详细研究了两种喹喔啉衍生物激发三重态在乙腈体系中的动力学过程,得到激光脉冲作用后不同时间的瞬态吸收光谱及激发三重态自猝灭反应动力学常数．并以五种缺电子烯烃作为猝灭剂,得到了基态缺电子烯烃对喹喔啉衍生物激发三重态的猝灭反应动力学常数,阐明了猝灭反应机理．     

芘四磺酸钠水溶液激光闪光光解机理

采用激光闪光光解-瞬态吸收光谱技术研究了355nm激光作用下芘四磺酸钠(PyTS)水溶液的光化学反应机理及其产生水合电子的动力学行为.研究首次发现PyTS水溶液激发单线态(PyTS1*)在260nm、激发三线态(PyTS3*)在300nm及阴离子自由基(PyTS-?)在330nm处的特征吸收峰;分析了生成的水合电子(e-aq)的主要反应途径包括自猝灭反应及与PyTS的反应,得到水合电子与PyTS反应的准一级速率常数为2.7′105s-1;并计算得到在此实验条件下,PyTS水溶液经双光子吸收产生的水合电子量子产率为3.2′10-2.     

Determination of Astaxanthin and Canthaxanthin Triplet Properties in Different Polarities of the Solvent by Laser Flash Photolysis

Triplet‐triplet extinction coefficients for astaxanthin ( I ) and canthaxanthin ( II ) in different deaerated polarity solutions of MeCN and benzene were evaluated by laser flash photolysis at 298 K in the spectral region from 350 to 650 nm by energy transfer method, employing 2‐acetonaphthone as sensitizer. The triplet‐triplet extinction coefficients in MeCN and benzene were different in terms of the carotenoid present. The maximum triplet‐triplet extinction coefficient was 0.1–1.7×10⁵ L·mol⁻¹·cm⁻¹ in different solvents. The rate constants of triplet decay were I : 1.25×10¹⁰ L·mol⁻¹·s⁻¹, II : 1.12×10¹⁰ L·mol⁻¹·s⁻¹ in MeCN; and I : 1.75×10¹⁰ L·mol⁻¹·cm⁻¹, II : 3.27×10¹⁰ L·mol⁻¹·s⁻¹ in benzene. The bimolecular rate constants of energy transfer from triplet excited 2‐acetonaphthone to carotenoids were determined from the linear regression of the decay rate constant of 2‐acetonaphthone triplet at varying carotenoid concentrations. The triplet lifetimes of ³AST* and ³CAN* in different solvents were also determined. The results indicated that triplet energy transfer was nearly diffusion‐controlled.     

没食子酸的激光光解研究

The transient species of gallic acid(GA)have been studied by 266 nm nanosecond laser flash photolysis inaqueous solution and acetonitrile.The intermediate with absorption at 320 nm was identified as excited triplet state(~3GA~*),the decay rates of which were obtained in aqueous solution and acetonitrile respectively.Energy transferfrom ~3GA~* to β-carotene was observed and the energy transfer rate constant k_(ent)was determined to be 2.2×10~9mol~(-1)·L·s~(-1).GA underwent photoionization during photolysis and the quantum yield of photoionization was de-termined to be 0.12 at room temperature with KI as a reference.     

纳秒激光闪光光解装置功能扩展──有机非线性材料二阶非线性系数测定

纳秒级激光闪光光解装置可用于有机光化学、光物理过程，瞬态发光和吸收的动力学过程的研究，在不改变原装置整体布局和结构的基础上，建立了有机非线性光学材料的二阶非线性系数测定方法，并为国家８６３专家委员会承担过仲裁测定。     

纳秒激光闪光光解装置功能扩展──有机非线性材料二阶非线性系数测定

纳秒级激光闪光光解装置可用于有机光化学，光物理过程，瞬态发光和吸收的动力学过程的研究。在不改变原装置整体布局和结构的基础上，建立了有机非线性光学材料的二阶非线性系数测定方法，并为国家８６３专家委员会承担过仲裁测定。     

激光闪光光解技术研究Pt4+掺杂提高TiO2光催化活性机制

通过用纳秒激光直接激发Pt⁴⁺掺杂的TiO₂透明溶胶体系,研究了440 nm处O^-吸收光谱的衰减过程.O^-是被捕获的正空穴的信号,是光催化反应过程中产生OH.自由基的决定影响因素.OH.浓度和衰减速度决定了光催化反应的效率.研究表明,O^-的寿命可以长达几十微秒.利用纳秒激光闪光光解的研究结果阐明了Pt⁴⁺掺杂显著提高TiO₂光催化活性的机制.     

C60-地塞米松的激光激发

利用激光光解装置检测了C60-地塞米松(C60-DE)的苯溶液在355 nm激光照射下产生的激发三重态, 3C60-DE*出现四个吸收峰, 分别位于700、440、350 和310 nm. 在330 nm处观察到了它的漂白吸收最大值, 这与其基态吸收最大值相对应. 3C60-DE*能够将能量转移给O2分子而淬灭. 与3C60*相比, 3C60-DE*的三重态鄄三重态(T-T)淬灭速率常数减小(3C60*为(5.03±1.31)×109 L·mol-1·s-1, 3C60-DE*为(3.53±0.87)×109 L·mol-1·s-1), 而寿命增加了(3C60*为(12.0±2.6) μs, 3C60-DE*为(18.0±3.3) μs), 这可能是C60分子上连接了地塞米松分子后减小了C60球之间碰撞的几率所致.     

环-Phe-His二肽水溶液的激光光解

报导了利用纳秒级激光光解瞬态吸收光谱技术研究环苯丙氨酰组氨酰水溶液光解和光敏化作用过程。发现了该环肽在２４８ｎｍ激光的激励下产生光电离和光解离,光电离和光解离过程发生在苯丙氨酸残基上,生成具有３２０ｎｍ和４１０ｎｍ特征吸收的自由基,光解离发生具有３２０ｎｍ特征吸收的苄基自由基。而具有亲电子性的丙酮能在该环肽的苯丙氨酸残基的苯环上抽取电子,形成３２０ｎｍ和４１０ｎｍ的特征吸收峰,求出了自由基的有关动     

CS2与亚硝酸水溶液复相体系的激光闪光光解

利用激光光解-瞬态吸收技术研究了氮气饱和条件下CS2与亚硝酸水溶液复相体系的355nm光解机理.瞬态吸收光谱分析结果表明:CS2与·OH自由基快反应生成CS2OH,产生的CS2OH继续与HONO反应生成CS2OH-HONO加合物,其吸收峰分别为285,305,475,490和980nm,反应CS2OH+HONOCS2OH-HONO的二级速率常数为(2.79±0.05)×108L/(mol·s);230nm处的吸收峰归属为CS2NO+,其一级衰减速率常数为1.28×105s-1.     

pH Dependence of Photochemical Kinetics of Thioxanthen-9-one from Nanosecond Time-Resolved Laser Flash Photolysis

pH dependent fluorescence emission of a thioxanthone-based probe has been reported recently. The potential determinant factors of pH dependence may provide important clues to design novel thioxanthone-based probes in the future. pH dependence of photochemical kinetics of thioxanthone itself was investigated in this work using nanosecond time-resolved laser flash photolysis. The nanosecond time-resolved transient absorption spectra and kinetics of TX in aqueous acetonitrile were recorded, as well as for a model reaction system including TX with diphenylamine (DPA) as a co-initiator. Besides the well-known absorption peak of \begin{document}$ ^3 $\end{document}TX\begin{document}$ ^* $\end{document}, other peaks at 417, 518, 673 and 780 nm, have been reliably attributed to major intermediates in the overall reaction between TX and DPA with photolysis, which has been confirmed to occur along a multistep process. In the strong acidic solution (pH\begin{document}$ \approx $\end{document}3.0), TX and protonated TX ions (TXH\begin{document}$ ^+ $\end{document}) coexist due to protonated equilibrium. Consequently, high proton concentration promotes the predominant decay pathway after photolysis from electron transfer to proton affinity. Subsequently, the different primary products, \begin{document}$ ^3 $\end{document}TXH\begin{document}$ ^{+*} $\end{document} or TX\begin{document}$ ^{\bullet-} $\end{document}, proceed different secondary reaction channels. In addition, within the wide pH range from weak acid (pH = 5.0) to alkaline solution (pH = 13.0), the overall reaction mechanism and rates do not show visible changes.     

Photophysical Properties and Photoinduced Electron Transfer between [60] Fullerene-Containing Cyclic Sulphoxide [C_(60)-C_6H_8SO] and Tetrathiafulvalene (TTF) by Laser Flash Photolysis

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Photoinduced Oxidation Reaction of Benzotrifluoride with OH Radical by the Laser Flash Method

The optical transient and kinetics characterizations of the transients formed in the reaction of OH with benzotrifluoride (BTF) were performed by a laser flash photolysis technique. The results indicated that the formation of π‐type adduct of C₆H₅(OH)CF₃ was the major reaction channel, and the δ‐type adduct of C₆H₅CF₃OH formation was an additional minor process in the oxidation reaction of BTF attacked by OH radicals yielded from the photolysis of H₂O₂. Addition of OH to the CF₃ group led to the fluoride ion elimination to yield α,α‐difluorophenylcarbinol (C₆H₅CF₂OH). Trifluoromethylphenol (HOC₆H₄CF₃) of meta‐, para‐ and ortho‐substituted isomers resulted from the addition of OH to the BTF aromatic ring.     

Laser Flash Photolysis Mechanism of Anthraquinone-2-Sodium Sulfonate in Pyridine Ionic Liquid/Water Mixed System

The photochemical reaction process of anthraquinone-2-sodium sulfonate (AQS) in the mixture of water (H₂O) and N-butylpyridinium tetrafluoroborate ([BPy][BF₄]) was studied using the laser flash photolysis technique. Experimental results show that the excited triplet of AQS (³AQS^*) could react rapidly with H₂O and the transient absorption spectra greatly changed by increasing the volume fraction of the ionic liquid (V_IL) in [BPy][BF₄]/H₂O mixtures. The absorbance at 510 nm increased gradually with increasing V_IL when 0< V_IL< 0.1. By contrast, the absorbance decreased gradually when V_IL>0.1. Otherwise, the absorbance of the band near 380 nm steadily increased. The apparent kinetic parameters of transient species B and ³AQS^* are obtained approximately. ³AQS^* abstracting hydrogen from [BPy]⁺ was also explored. It was deduced that the 350-420 nm band was the superposition of the peaks of ³AQS^* and AQSH^·. The two reactions of ³AQS^* with [BPy][BF₄] and H₂O are a pair of competitive reactions. We also concluded that the entire reaction processes slow down in the case of high [BPy][BF₄] concentrations.     

二氟沙星激发态氧化损伤氨基酸和脱氧鸟苷酸的激光光解研究

The reactions of triplet-state difloxacin (DFX) with various amino acids and deoxyguanylic acid in aqueous media were studied using laser flash photolysis. Tryptophan, tyrosine, cysteine, and 2'-deoxyguanosine-5'-monophosphate (dGMP) were found to completely quench the triplet state of DFX in aqueous solution, the corresponding second-order rate constants being 1.97×10⁸, 1.48×10⁸, 1.72×10⁸, and 6.92×10⁷ dm³·mol^－1·s^－1. The quenching mechanism involves electron transfer to the photoexcited triplet state of DFX from the tryptophan, tyrosine, cysteine, and dGMP moieties, followed by fast protonation of the resulting DFX anion radical.     

Photoproducts of the Photodynamic Therapy Agent Verteporfin Identified via Laser Interfaced Mass Spectrometry

Verteporfin, a free base benzoporphyrin derivative monoacid ring A, is a photosensitizing drug for photodynamic therapy (PDT) used in the treatment of the wet form of macular degeneration and activated by red light of 689 nm. Here, we present the first direct study of its photofragmentation channels in the gas phase, conducted using a laser interfaced mass spectrometer across a broad photoexcitation range from 250 to 790 nm. The photofragmentation channels are compared with the collision-induced dissociation (CID) products revealing similar dissociation pathways characterized by the loss of the carboxyl and ester groups. Complementary solution-phase photolysis experiments indicate that photobleaching occurs in verteporfin in acetonitrile; a notable conclusion, as photoinduced activity in Verteporfin was not thought to occur in homogenous solvent conditions. These results provide unique new information on the thermal break-down products and photoproducts of this light-triggered drug.     

光动力疗法用糖基光敏剂的研究进展

作为光动力疗法中至关重要的决定性因素,光敏剂的研究受到越来越多的重视.而糖基的引入,可以大大提高光敏剂母体的膜透过性和特异吸收性.从糖基光敏剂的母体结构、糖基光敏剂分子的构效关系、糖基的作用机理以及糖基光敏剂的药物动力学和代谢产物这四个方面对近年来糖基光敏剂的研究现状进行了综述,对其发展趋势进行了展望.     

CCl4的光解微观机制研究

利用激光光解瞬态吸收光谱技术,研究有氧和无氧条件下CCl4的激光光解.结果表明,在248 nm激光作用下, CCl4发生了单光子吸收,反应生成{CCl4－Cl}σ电荷转移复合物、(CCl3＋…Cl－)离子对、CCl3O2过氧自由基等瞬态物种,它们的衰减过程是表观一级反应. {CCl4－Cl}σ电荷转移复合物在有氧/无氧条件下的拟合衰减速率常数分别是3.38×106 s－1和3.65×106 s－1,它的形成不受氧气含量影响. (CCl3＋…Cl－)离子对在有氧/无氧条件下的拟合衰减速率分别为3.73×107 s－1和3.02×107 s－1,它的形成也不受氧气含量影响, CCl3O2过氧自由基需在有氧条件下形成,拟合衰减速率是2.32×104 s－1.     

N-羟乙基-1,8-萘二酰亚胺探针与核苷间电子转移的激光闪光光解研究

核酸与核酸前体参与的电子转移(ET)作用能够直接或间接导致核酸主链和碱基侧链的断裂,因此对核酸碱基光动态损害机理的深入研究具有重要的理论和实际意义．其中,核酸荧光探针逐渐成为研究生物分子的主要技术之一,借助于时间分辨的瞬态吸收光谱技术,检测荧光探针激发态物种及其与核酸之间发生电子转移作用而产生的活性中间体,能够深入了解光断裂反应的最初步骤,揭示核酸断裂电子转移反应的微观机理．     

靶标性酞菁类光敏剂的光动力疗法研究进展

光动力治疗（Photodynamic therapy,PDT）作为一种有别于传统癌症治疗方式的新型疗法,近些年来受到了科学家们越来越多的关注.它凭借着自身创伤性小,毒性低微,适用性好,可协同手术治疗以及可重复治疗等独特优势,在许多肿瘤的治疗方面有着广泛的应用.本文简要概述了光动力疗法的原理以及光敏剂的发展历程,并对理想光敏剂的特点作了总结.目前,以酞菁类化合物为主的第三代光敏剂已经成为光动力疗法的研究热点,然而如何提高光敏剂分子的靶向性达到精准的光动力治疗仍然是亟待解决的问题.因此,主要综述了近年来靶向性酞菁类光敏剂的研究进展,并对未来光敏剂的重点研究方向做出了展望.从目前来看,如何克服癌症低氧微环境的限制,发展Type I型不依赖氧的体系以及光穿透力强的靶向光敏剂在光动力治疗方面存在着巨大的潜质,有望成为新一代十分优良的光动力疗法用光敏剂.