meso—四—（取代苯基）卟吩衍生物产生单线态氧的ESR研究

随着肿瘤光动力疗法(Photodynamic Therapy,PDT)的不断发展,出现了一系列新光敏剂,其中,meso-四-(取代苯基)卟吩衍生物是一类肿瘤选择性摄入率高、理化性质稳定的光动力敏化剂,近年来,作者设计并合成了一组meso-四-(取代苯基)卟吩衍生物,并初步观察了它们对细胞及小鼠移植瘤的光动力学效应,为了进一步比较不同卟吩衍生物的光敏化     

氯氰菊酯光敏降解中单线态氧机理研究

光敏剂亚甲兰,核黄素及玫瑰红Ｂ可加速氯氰菊酯（ＣＰＭ）的光解作用。这些物质的敏化作用主要通过激发基态氧为单线态氧来实现。光敏剂和氧均是敏化光降解不可缺陷少的条件。１／Ｋｅｘｐｔｌ与「Ａ」的关系证实了单线态氧氧化机理。在亚甲兰、核黄素存在下氯氰菊酯ＫＡ分别为６．４９＊１０＾６ｌ．ｍｏｌ＾－１．ｓ＾－１和２．２７＊１０＾６Ｌ．＾－１。氯氰菊酯的光解速率在一定范围内,随光敏剂浓度的增加而增加,过量的光敏剂将减少体系的透光率而导致氯氰菊酯光解速率降低,单线态氧探针性物质即竞争反应的引入将明显降低氯氰菊酯的光解速率,同时,不同极性溶剂因其对单线态氧猝灭能力的不同也会明显改变氯氰菊酯的光解速率。     

射流式单重态氧发生器研究

单重态氧O2(a1△g)是迄今唯一能用纯化学反应高效产生的具有长寿命的亚稳激发态分子.为了考察提出的用两个O2(1△)能量汇集反应生成氧第二单重激发态O2(b1∑+g)以实现近可见短波长化学激光方案的现实性,设计和实验了一个氯流量为3～10 mmol/s的射流式单重态氧发生器(JSOG).考察了三种具有不同孔径和孔数目的喷头、氯气流量和脱水冷阱温度等对JSOG出口的O2(1△)浓度、O2(1△)分压、氯利用率及水蒸气含量的影响.发现用聚氯乙烯管作冷阱时,最佳冷阱介质温度为-140～-150℃,对此提出了O2(1△)表面脱活与脱水互相竞争的解释.在最佳条件下,可将O2(1△)气中水分压降低至4 Pa,这一结果是首次报导.     

Kinetics Study on Reaction between Dihydroartemisinic Acid and Singlet Oxygen: An Essential Step to Photochemical Synthesis of Artemisinin

Artemisinin is an excellent antimalarial drug widely used in clinical medicine. However, due to the limitation of natural source of artemisinin, the chemical synthesis of artemisinin has achieved substantial attention. Dihydroartemisinic acid is a key precursor for the synthesis of artemisinin. The reaction of dihydroartemisinic acid with singlet oxygen to form peroxide is a pivotal step in the photochemical preparation of artemisinin. Nevertheless, the reaction kinetics of dihydroartemisinic acid with singlet oxygen has not been investigated previously. Herein, we report the rate constants of the reaction between dihydroartemisinic acid and singlet oxygen. By directly detecting the luminescence decay kinetics of singlet oxygen at 1270 nm at room temperature, the reaction rate constants of singlet oxygen and dihydroartemisinic acid in different solvents are obtained to be 1.81\begin{document}$\times$\end{document}10\begin{document}$^5$\end{document} (mol/L)^-1·s^-1 in CCl\begin{document}$_4$\end{document}, 5.69\begin{document}$\times$\end{document}10\begin{document}$^5$\end{document} (mol/L)^-1·s^-1 in CH\begin{document}$_3$\end{document}CN, and 3.27\begin{document}$\times$\end{document}10\begin{document}$^6$\end{document} (mol/L)^-1·s^-1 in DMSO, respectively. It is found that the reaction rate constants of dihydroartemisinic acid with singlet oxygen increase as polarity of the solvent increases among the three solvents. These results provide fundamental knowledge to optimize experiment conditions of photochemical synthesis of artemisinin for improving the yields of artemisinin.     

A High Sensitivity Detection Method of Singlet Oxygen and Superoxide Anion

This paper, for the first time, reports a method that can be used as a highly sensitive probe for singlet oxygen (^1O2) and superoxide anion (O2^-) in vitro or in vivo. FCLA(3,7-dihydro-6-{4-[2-(N‘-(5-fluoresceinyl)thioureido)ethoxy]phenyl}-2-methylimidazo{1,2-a}pyrazin-3-one sodium salt), a chemiluminescence (CL) analysis reagent, has been reported to sensitively react with ^1O2 and O2^- to emit photons with a spectral peak of 525nm. In this work,when human serum albumin (HSA) was added into FCLA solution to enhance the CL intensity,approximately 20 times, compared to that without HSA. The enhanced CL had the same 525 nm spectral peak, identical to that without HSA. By gradually reducing the molecular oxygen content in the solution, we find that the auto-oxidation of oxygen molecules dissolved in the solution plays an important role in the CL process. Based on these experimental evidences, we propose a novel and highly sensitive detection method of ^1O2 and O2^- which may have a great potential in chemical and medical applications.     

咪唑与单线态氧(1O2)1,2-环加成反应的理论研究

采用较新的半经验分子轨道方法Austin Model 1(简称AM1方法), 辅以Berny梯度优化方法, 对单线态氧(~1O_2)与咪唑的1,2-环加成反应,进行了理论研究。计算获得实验尚未检测到的4,5-二氧环丁烷(4,5-dioxetane)的结构, 并在反应势能面上找到单重态双自由基中间体及通过该中间体的两步反应的过渡态。通过对过渡态的结构特征、虚振动方向以及对反应过程的电荷分布情况、轨道相互作用等的分析, 说明该反应是经由单重态双自由基中间体的分步反应。两步反应的活化势垒分别为39.2 kJ·mol~(-1)和150.5 kJ·mol~(-1)。     

Electrochemical Monitoring of Singlet Oxygen Production

The exploitation of singlet oxygen generating compounds as a means of targeted therapies drives the need to develop methods for assessing the efficacy of such compounds and their capacity for generating the reactive oxygen species. Degradation of diphenylisobenzofuran by singlet oxygen is widely used as a spectroscopic probe but its application can be problematic. An alternative detection strategy exploiting the electrochemical monitoring of the quencher concentration, by square wave voltammetry, has been shown to provide a more sensitive and flexible option that could be used to address the increasing interest in photosensitizing materials.     

Generation of Singlet Oxygen from Ozone Catalysed by Phosphinoferrocenes

Summary. A novel chemical source of singlet oxygen based on the conversion of ozone by 1,1-bis(triphenylphosphino)ferrocene as catalyst was developed into a feasible method for a preperative scale. This is, to our best knowledge, the first application of substituted ferrocenes as oxidation catalysts.     

Synthesis,Characterization, and Singlet Oxygen Sensitization by Antimony (III/V) Corrole Complexes

The synthesis, structural, spectroscopic characterization, and DFT/TD-DFT calculations of antimony corroles are reported herein. The studied complexes can be described as [(Corr)Sb^III] and [(Corr)(oxo)Sb^V]₂, where Corr is the trianion of corrole. All these complexes are diamagnetic in nature as is evident from sharp peaks with normal chemical shifts in the ¹H NMR spectra. Single crystal XRD analysis reveals that the antimony(V) corrole complex is the bis-μ-oxo-bridged dinuclear antimony(V). Both the tetra and hexa-coordinated [(Corr)Sb^III] and [(Corr)(oxo)Sb^V]₂ antimony complexes adopt domed-structure with weak d-π electron coupling. The Sb−O bond distances in the co-facial dimer of [(Corr)(oxo)Sb^V]₂ are 1.9802(16) Å (DFT: 2.0141 Å ) (for Sb1−O1), and 1.9639(17) Å (DFT: 1.9957 Å ) (for Sb2−O2) respectively. We observed that even though iodosobenzene is frequently used to oxidize [(Corr)Sb^III] species, the oxidation of [(Corr)Sb^III] is indeed very facile in nature and it even occurred in the air-equilibrated CHCl₃ solution while storing for few days. Excitation of these antimony (III/V) corrole complexes in DCM/MeOH (1 : 1) at 77 K results in red emission with maxima at 640–720 nm. The singlet oxygen production of [(Corr)(oxo)Sb^V]₂ has a quantum yield of 69 % and is two times higher than the analogous [(Corr)Sb^III] derivatives.     

亚磷酸三苯酯臭氧化合物分解产生单重态氧的研究

This letter reports a study on producing gas-phase O2（a1Δ）by decomposition of triphenyl phosphite ozonide（（C6H5O）3 PO3,TPPO3）under a number of reaction conditions. For the first time,the cooperative emission at wavelengths 634 and 703 nm of O2（a1Δ）generated by TPPO3 decomposition are observed. Specifically,under the condition of catalyzed decomposition by pyridine of TPPO3 solution in CFCl3 at low temperature,the emission spectrum is the same as that from the basic hydrogen peroxide plus chlorine reaction. This shows the feasibility of developing a new source for singlet delta oxygen. However,in the experiments of spontaneous decomposition of solid TPPO3 and thermal decomposition of TPPO3 solution on a high temperature surface,the spectra have a wide emission background around the 634 and 703 nm peaks,which indicates the production of some excited species than O2（a1Δ）. Besides,there are about 2%-3% CO and 1. 5%-2% CO2 in the gaseous products together with a small amount of insoluble in acetone solid product,which imply that other than the formation of O2（a1Δ）and TPPO by unimolecular decomposition of TPPO3,more complicated reactions may take place. The study of the reaction mechanism,the optimization of the expertise of O2（a1Δ）generation by TPPO3 decomposition as well as measurement of absolute concentration of O2（a1Δ）are under way.     

Kinetics Study on Reaction of Atenolol with Singlet Oxygen by Directly Monitoring the 1O2 Phosphorescence

The pharmaceutically active compound atenolol, a kind of $\beta$-blockers, may result in adverse effects both for human health and ecosystems if it is excreted to the surface water resources. To effectively remove atenolol in the environment, both direct and indirect photodegradation, driven by sunlight play an important role. Among indirect photodegradation, singlet oxygen (¹O₂), as a pivotal reactive species, is likely to determine the fates of atenolol. Nevertheless, the kinetic information on the reaction of atenolol with singlet oxygen has not been well investigated and the reaction rate constant is still ambiguous. Herein, the reaction rate constant of atenolol with singlet oxygen is investigated directly through observing the decay of the ¹O₂ phosphorescence at 1270 nm. It is determined that the reaction rate constant between atenolol and ¹O₂ is 7.0×10⁵ (mol/L)$^{-1}\cdot$s^-1 in D₂O, 8.0×10⁶ (mol/L)$^{-1}\cdot$s^-1 in acetonitrile, and 8.4×10⁵ (mol/L)$^{-1}\cdot$s^-1 in EtOH, respectively. Furthermore, the solvent effects on the title reaction were also investigated. It is revealed that the solvents with strong polarity and weak hydrogen donating ability are suitable to achieve high rate constant values. These kinetics information on the reaction of atenolol with singlet oxygen may provide fundamental knowledge to the indirect photodegradation of $\beta$-blockers.     

1,4—双（苯基乙炔基）苯及其双取代苯基衍生物的研究

合成了1,4-双(苯基乙炔基)苯及其双取代苯基衍生物。测定了它们的荧光量子产率、激光转换效率、红外光谱、拉曼光谱,指派了主要官能团的特征频率,讨论了化合物结构和取代基效应。     

Study on the Total Synthesis of Hainanolide(V)-Oxidation of the Tricyclic Alkenes with Singlet Oxygen

Inthepreviouspapers'wereportedthatfromthemotherliquidofrecrystalizingex0cy-cIoadditivelfromintramolecularDiels-Alderreaction(IMDA)'0nexposuret0airforalongperiod,ahydroperoxide2wasisoIated.ThiswasexplainedastoberesuItedfromoxidati0nofthealkeneby'O,withsubsequentrearrangement.Perceivingthehydroperoxidemightserveasavaluableintermediateinthetotalsynthesisofhainan0Iide,ph0tochemicalsinglet0xygenoxidati0n,usingmeso-tetraPhenylporPhyrin(TPP)assensitizingagent',ofsixunsaturatedtricycIicc0mpounds…     

非水溶性meso-四-(4-乙酰氧基苯)卟啉的合成及其与铅显色反应的研究

目前在用水溶性卟啉衍生物作显色剂方面已有文献总结^[1]。但对非水溶性卟啉则研究得较少。就测定痕量铅而言,皆用水溶性卟啉衍生物,而用非水溶性卟啉测定铅,则尚未见报导^[2-6]。     

荧光探针法研究铜离子-姜黄素体系中1O2的反应机理及在O2·-存在下1O2的测定

以1,3-二苯基异苯并呋喃(1,3-Diphenylisobenzofuran, DPBF)为荧光探针, 研究了姜黄素(Curcumin, CUR)在铜离子催化下产生的单线态氧(1O2), 其反应机理为姜黄素与溶液中的氧分子快速作用产生O2·-和H2O2等活性氧物种, 同时Cu2+与姜黄素形成复合物, 再与H2O2形成过氧化物过渡态, 过氧化物进一步与H2O2发生类Haber-Weiss反应生成1O2, 且只有Cu2+和Cu+离子可催化姜黄素并产生1O2. 1O2在1.37×10-8～3.66×10-7 mol/L浓度范围内与荧光强度下降值ΔIF有良好的线性关系, 检出限为4.12×10-9 mol/L.     

Quenching of Singlet Oxygen by Tertiary Aliphatic Amines. Structural Effects on Rates and Products

A kinetic and product study of the reaction of a series of α‐methyl‐substituted N‐methylpiperidines with thermally generated ¹O₂ in MeCN was carried out. It was found that as the number of α‐methyl groups (Me in α‐position relative to the N‐atom) increases, the rate of ¹O₂ quenching (physical plus chemical) slightly decreases. This finding shows that, with respect to the reaction rate, steric effects are much more important than electronic effects as the latter should have produced the opposite result. The opposite outcome was instead found for the chemical quenching that leads to the N‐demethylation products and N‐formyl derivatives. The same trend was observed for the ratio between N‐demethylation and formation of the N‐formyl derivatives (NH/NCHO ratio). All these results are consistent with the mechanism reported in Scheme 1 where an exciplex is first formed that by a H‐atom transfer process produces an α‐amino‐substituted C‐radical. The latter forms the product of N‐demethylation by one electron oxidation, or affords the N‐formyl derivative by radical coupling (Scheme 1). Similar results were obtained with N,N‐dimethylcyclohexanamine. However, this ‘acyclic’ amine exhibited behaviors quite distinct from those of the N‐methylpiperidines series, with respect to reaction rate, extent of chemical quenching, and NH/NCHO ratio.     

辐照交联聚甲基乙烯基硅氧烷的ESR谱研究

本文研究了GY-131医用级聚甲基乙烯基硅氧烷(PMVS)在辐照交联中的自由基产生和衰减的ESR潜,以及SiO₂填料对交联的影响。     

对苯撑乙烯低聚物光氧化降解研究

五种对苯撑乙烯低聚物的光氧化降解反应表明,给电子基团能促进其光氧化降解,而吸电子基团却能提高它们的光稳定性,这为用分子修饰的方法提高对苯撑乙烯类发光材料的稳定性提供了理论基础。在自敏化和染料敏化的光氧化降解反应中,五种低聚物的降解速率顺序完全一致,意味着单线态氧（1O2）是其光氧化降解反应过程中的主要中间体,ESR自旋捕获实验进一步证实了上述诊断。     

Photosensitized Generation of Singlet Oxygen from (Substituted Bipyridine)ruthenium(II) Complexes

Photophysical properties in dilute MeCN solution are reported for seven Ru^II complexes containing two 2,2′‐bipyridine (bpy) ligands and different third ligands, six of which contain a variety of 4,4′‐carboxamide‐disubstituted 2,2′‐bipyridines, for one complex containing no 2,2′‐bipyridine, but 2 of these different ligands, for three multinuclear Ru^II complexes containing 2 or 4 [Ru(bpy)₂] moieties and also coordinated via 4,4′‐carboxamide‐disubstituted 2,2′‐bipyridine ligands, and for the complex [(Ru(bpy)₂(L)]²⁺ where L is N,N′‐([2,2′‐bipyridine]‐4,4′‐diyl)bis[3‐methoxypropanamide]. Absorption maxima are red‐shifted with respect to [Ru(bpy)₃]²⁺, as are phosphorescence maxima which vary from 622 to 656 nm. The lifetimes of the lowest excited triplet metal‐to‐ligand charge transfer states ³MLCT in de‐aerated MeCN are equal to or longer than for [Ru(bpy)₃]²⁺ and vary considerably, i.e., from 0.86 to 1.71 μs. Rate constants k_q for quenching by O₂ of the ³MLCT states were measured and found to be well below diffusion‐controlled, ranging from 1.2 to 2.0⋅10⁹ dm³ mol⁻¹ s⁻¹. The efficiencies f of singlet‐oxygen formation during oxygen quenching of these ³MLCT states are relatively high, namely 0.53 – 0.89. The product of k_q and f gives the net rate constant k for quenching due to energy transfer to produce singlet oxygen, and k_q−k equals k, the net rate constant for quenching due to energy dissipation of the excited ³MLCT states without energy transfer. The quenching rate constants were both found to correlate with ΔG^CT, the free‐energy change for charge transfer from the excited Ru complex to oxygen, and the relative and absolute values of these rate constants are discussed.     

Capacity of Tea Scavenging Singlet Oxygen Studied by Means of 1,3-Diphenylisobenzofuran as Fluorescence Probe

1 Introduction In recent years, the effects of reactive oxygen species(ROS) generated in the course of biological metabolism, such as superoxide(O_2~(-.)), hydrogen peroxide(H_2O_2), hydroxyl radical(HO~.) and singlet oxygen(~1O_2) on the human health have received more attention due to their vital roles in physiological functions. Normally, antioxidant molecules, superoxide dismutase and catalase in biological organism can scavenge excessive free radicals by a series of chemical reactions to keep the cells in a state of redox homeostasis[1].