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Photogeneration of the free radicals and singlet oxygen by chrysophanol from rheum

Science china chemistry 2004年第5期47卷 381-387页

作者： RAO Jing1,2. XIE Jie1, ZHAO Jingquan1 & ZHU Teng2.1. key laboratory of Photo{2., Center for molecular Science, Institute of {2., The Chinese Academy of Sciences, beijing 100080, china 2. University of Science and Technology beijing, beijing 10083, china 1. key laboratory of Photo{2. Center for Molecular Science Institute of Chemistry The Chinese Academy of Sciences 100080 Beijing China 2. University of Science and Technology beijing 10083 Beijing China

In the current work, chryosphanol (MHAQ) was isolated and purified from rheum, and the photosensitization activities were studied. In nitrogen-saturated DMSO solution, irradia- tion of chryosphanol (MHAQ) with visible light (>430 nm) produced the semiquinone radical anions (MHAQ??), which was intensified significantly by an electron donor NADH, suggesting electron transfer between the excited and ground state photosensitizer molecules. In an air-saturated DMSO solution, superoxide radical anions (O2.), trapped by DMPO, were detected. ?? It was proved that O2.was not originated from the singlet oxygen (1O2. but dependent on DMPO, ?? chrysophanol, oxygen and the irradiation time. The singlet oxygen and OH could also be pro- ? duced by the photosensitization of the photosensitizer. These suggest that chrysophanol pos- sesses the photosensitization activity via Type I mechanism and Type II mechanism. To evaluate the photosensitization activities of MHAQ, emodin and mixed anthraquinone derivatives ex- tracted from rheum, the relative productivities of O2.were estimated to be 1.8, 1.1 and 1.0 re- ?? spectively and the quantum yields for singlet oxygen to be 0.36, 0.53 and 0.14 respectively. Therefore, these low-cost pigments may be potentially used as phototherapeutic medicine for some kind of vascular diseases or photo-activated pesticides.

关键词： chrysophanol, ESR, semiquinone radical anions, superoxide radical anions, hydroxyl radical, singlet oxygen.

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STUDY ON PYROLYSIS OF POLYPHENYLSILSESQUIOXANE

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Chinese Journal of Polymer Science 2002年第6期20卷 573-577页

作者： Jun Ma Liang-he Shi Jian-min Zhang Bai-yu Li De-yan Shen Jian Xu state key {2. of Polymer Physics & chemistry Center for molecular Science, Institute of chemistry,Chinese Academy of Sciences, beijing 100080 china Chinese Acad Sci Inst Chem State Key Lab Polymer Phys & Chem Ctr Mol Sci Beijing 100080 Peoples R China

X-ray photoelectron spectroscopy and Raman spectroscopy were' used to determine the chemical change of polyphenylsilsesquioxane (PPSQ) during pyrolysis in flowing nitrogen. Two temperature ranges were found for pyrolysed PPSQ below and above 600degreesC, respectively. The former is related to the rearrangement of PPSQ backbone and the latter reflects that most of backbone structure of PPSQ might be broken down and unorganized. Carbon formed in carbonization of PPSQ sample pyrolysed at 900degreesC should be sp(3) bonded carbon with crystallite size effects or defects.

关键词： pyrolysis polyphenylsilsesquioxane

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FORMATION OF MESOPHASE MONO-DOMAINS AND MICRO-STRUCTURES IN THIN FILMS OF A SERIES OF COPOLYETHERS CONTAINING BOTH ODD-NUMBERED METHYLENE UNITS

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Chinese Journal of Polymer Science 2001年第4期19卷 391-397页

作者： Feng-chao Xie Jie-ping Liu Dong-hang Yan Tian-bai He Ru-qing Zheng Er-qiang Chen state key {2. of Polymer Physics and chemistry, Changchun Institute of Applied chemistry, Chinese Academy of Sciences, Changchun 13002., china Department of Polymer Science and engineering college of chemistry peking University beijing 100871, china Chinese Acad Sci Changchun Inst Appl Chem State Key Lab Polymer Phys & Chem Changchun 130022 Peoples R China peking Univ Coll Chem Dept Polymer Sci & Engn Beijing 100871 Peoples R China

The structural and morphological evolution of mono-domains in thin films has been investigated for a series of liquid crystalline (LC) copolyethers. The copolyethers studied were synthesized by the reaction of 1-(4-hydroxy-4 ' -biphenylyl)-2.(4-hydroxyl-phenyl)propane (TPP) with 1,7-dibromoheptane and 1,11-undecane at different compositions (coTPPs-7/11). In contrast to the solution-cast thin films without annealing, which exhibit the isotropic homogeneous molecular orientation, mono-domains with a homeotropic alignment were found in coTPP-7/11(5/5) after the thin films were annealed in the high-temperature columnar phase (Phi '). Similar to the nucleation process in polymer crystallization, transmission electron microscopic observations show that small mono-domains appear in the initial stage of annealing, where molecules form a uniaxial in-plane chain orientation. With increasing annealing time, the molecular orientation gradually became tilted with respect to the substrate surface, and finally, a uniaxial homeotropic molecular orientation was achieved after a prolonged annealing time. The lateral size of mono-domains was found to increase continuously with annealing time and grew into a circular shape, indicating an isotropic lateral growth scheme which implies a hexagonal molecular packing proved by the electron diffraction experiments.

关键词： main-chain liquid crystalline polymer structure morphology

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A density functional study on magnetic exchange interaction between Mn(II) ion and nitronyl nitroxide radical in trans- and cis-metal-radical complexes

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Science china chemistry 2005年第5期 20-32页

作者： WEI Haiyan, WANG Fan & CHEN Zhida state key {2. of Rare Earth Materials chemistry and Applications, college of chemistry and molecular engineering, peking University, beijing 100871, china

The magneto-structural correlation between a Mn(II) ion, coordinated in an octahe-dral environment, and two nitronyl nitroxide radical ligands in trans- and cis-metal-radical com-plexes is investigated by the broken symmetry (BS) approach within density functional theory (DFT). The dependences of coupling constants J on three structural parameters: (i) bond angle θ (Mn-O-N (nitroxide)); (ii) rotating angle ψ, defined by the nitronyl nitroxide radical plane rotating around the axial Mn-O (nitroxide); (iii) bond distance R (Mn-O (nitroxide)) are directly calculated. Our calculations showed that both trans- and cis-Mn(II)-radical complexes behave a stronger antiferromagnetic interaction, consistent with experiments. In view of {2. orbital theory, the direct exchanges, including σ-type and π-type exchanges, are responsible for the magnetic ex-change pathways. There is a preferable linear correlation between the calculated coupling con-stants J and the overlap integral squares Sa2. between the local magnetic orbitals at the various rotating angle ψ at the fixed bond angle θ and bond distance R, in both trans- and cis-Mn(II)- radical complexes.

关键词： density functional theory broken-symmetry approach magnetic exchange molecular magnetism Mn(II)-NITR complex.

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Comparison of photovoltaic devices based on MEH-PPV with various molecular weights

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Chinese Science Bulletin 2004年第21期49卷 2259-2261页

作者： KANG Bonan1,2. WANG Liduo1, YANG Yong1 & QIU Yong1 1. key laboratory of Organic Optoelectronics & {2. engineering of Ministry of Education, Department of chemistry, Tsinghua Univer- sity, beijing 100084, china 2. state key laboratory on Integrated optoelectronics, Jilin University Region, Changchun 13002., china key laboratory of Organic Optoelectronics & {2. engineering of Ministry of Education Department of Chemistry Tsinghua University Beijing 100084 China

Polymer photovoltaic devices based on poly (2. methoxy-5-(2. -ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH- PPV) with three weight-average molecular weights (Mw) have been fabricated with the device structure of ITO/PEDOT/ MEH-PPV/Ca/Ag, and the effect of the molecular weight on photovoltaic properties has been investigated. The experi- mental results show that the high molecular weight of MEH- PPV leads to low series resistance (Rs) and high short-circuit current. The low molecular weight of MEH-PPV leads to high shunt resistance (Rsh) and high open-circuit voltage. When the molecular weight is 6×105, the highest power con- version efficiency was observed.

关键词： MEHPPV 分子量光电器件载流子迁移率串联电阻并联电阻聚(2.甲氧基-5-(2.-乙基-乙氧基)-1,4-亚苯基乙烯撑)

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Application of Genetic Algorithm to the QSAR Research of Pyrrolobenzothiazepinones and Pyrrolobenzoxazepinones-Novel and Specific Non-Nucleoside HIV-1 Reverse Transcription Inhibitors

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Chinese Chemical Letters 1998年第7期9卷 651-654页

作者： Ting Jun HOU Jun Mei WANG You Yong LI Xiao Jie XU(chemistry department, Beida-Jiuyuan molecular Design {2., peking University,beijing 100871) peking Univ Dept Chem Beida Jiuyuan Mol Design Lab Beijing 100871 Peoples R China

Genetic Algorithm (GA) was used to study the quantitative structural parameters and activity relationship of pyrrolobenzothizepinones and pyrrolobenzoxazepinones's inhibitory activities with non-nucleoside HIV-1 reverse transcriptase (RT). A group of linear polynomial models with good relationship have been built to get some useful information that other methods can not offer.

关键词： QSAR GA(genetic algorithm) HIV

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Crystal Structure of Triethyl 6-benzoyl-3a-(4-fluorophenyl)-2.3,3a,4,5,6-hexahydro-5-methyl-1H-pyro〔1,2.a〕〔1,5〕benzodiazepine-1,2.3-tricarboxylate

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Chinese Journal of structural chemistry 1999年第4期 18-22页

作者： WANG HongZhong\ XU JiaXi\ MI BaoYu\ JIN Sheng* (college of chemistry and {2. engineering, peking University, beijing 100871)

１ＩＮＴＲＯＤＵＣＴＩＯＮＳｉｎｃｅｂｉｏｌｏｇｉｃａｌａｎｄｐｈａｍａｃｏｌｏｇｉｃａｌａｃｔｉｖｉｔｉｅｓｈａｖｅｂｅｅｎｗｅｌｋｎｏｗｎｆｏｒｎｕｍｅｒｏｕｓｈｅｔｅｒｏｃｙｃｌｉｃａｒｏｍａｔｉｃｔｒｉｃｙ... 详细信息

１ＩＮＴＲＯＤＵＣＴＩＯＮＳｉｎｃｅｂｉｏｌｏｇｉｃａｌａｎｄｐｈａｍａｃｏｌｏｇｉｃａｌａｃｔｉｖｉｔｉｅｓｈａｖｅｂｅｅｎｗｅｌｋｎｏｗｎｆｏｒｎｕｍｅｒｏｕｓｈｅｔｅｒｏｃｙｃｌｉｃａｒｏｍａｔｉｃｔｒｉｃｙｃｌｅｓｉｎｒｅｃｅｎｔｙｅａｒｓ...

关键词： crystal structure pyrro1 2.1 5benzodiazepine 1

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MORPHOLOGICAL STUDY ON THE ORIENTED CHITOSAN FILM OBTAINED FROM PRE-SHEARED LIQUID CRYSTALLINE SOLUTION IN DICHLOROACETIC ACID

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Chinese Journal of Polymer Science 2001年第4期19卷 385-390页

作者： Zhong-ming Hu Li-heng Wu Da-cheng Wu Shou-xi Chen state key {2. of Polymer Physics and chemistry, Center for molecular Science, Institute of chemistry Chinese Academy of Sciences, beijing 100080, china china Textile Academy beijing 10002., china Textile college, Sichuan University Chengdu 610065, china china Text Acad Beijing 100025 Peoples R China Chinese Acad Sci Inst Chem Ctr Mol Sci State Key Lab Polymer Phys & Chem Beijing 100080 Peoples R China Sichuan Univ Coll Text Chengdu 610065 Peoples R China

The oriented chitosan films obtained from pre-sheared liquid crystalline chitosan/dichloroacetic acid (DCA) solutions were studied by means of polarized optical microscopy (POM), scanning electron microscopy (SEM), infra-red dichroism technique and wide angle X-ray diffraction (WAXD). The sheer induced band texture in the film was found to correspond to the sinusoidal fibrillar microstructure along the shearing direction on the basis of POM and SEM observations. The sinusoidal fibril was found to be lying within the film plane. The model of chitosan molecular orientation in the pre-sheared film with band texture can be established assuming that the main chain orients in the shearing direction and the side group is perpendicular to the shearing direction. The WAXD azimuthal scanning at 2.theta = 2. degrees indicates that the (002. plane orients perpendicular to the shearing direction.

关键词： chitosan morphology orientation shear induced band texture liquid crystalline solution

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CRYSTALLIZATION KINETICS OF HOMOGENEOUS AND HETEROGENEOUS LLDPE

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Chinese Journal of Polymer Science 2002年第4期20卷 339-345页

作者： Hong-xiang Teng Wen-hong Tang Yi Shi Xi-gao Jin state key {2. of Polymer Physics and chemistry Center for molecular Science, Institute of chemistry Chinese Academy of Sciences beijing 100080 china Department of chemistry Jilin University Changchun 13002., china Chinese Acad Sci Ctr Mol Sci Inst Chem State Key Lab Polymer Phys & Chem Beijing 100080 Peoples R China Jilin Univ Dept Chem Changchun 130023 Peoples R China

Based on thermal analysis, the isothermal and nonisothemal crystallization kinetics of Ziegler-Natta catalyzed linear low density polyethylene (Z-N LLDPE) and metallocene catalyzed LLDPE (m-LLDPE) were studied. Treating the results with the Avrami equation and the Ozawa equation, the crystallization constant Igk and the Avrami exponent n were obtained. Some other crystallization parameters were also discussed. According to the different characteristics of the chain structures of Z-N LLDPE and metallocene LLDPE, their crystallization behaviors were analyzed. It is indicated that the homogeneity and heterogeneity of the two polymers act in different way during the crystallization process of polymers, including the nucleation and the growth of crystals under various conditions.

关键词： crystallization kinetics homogeneity heterogeneity LLDPE

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Maximum Entropy Method for Analyses of Fluorescence Correlation Spectra of Oligonucleotide Intra-chain Collision

Maximum Entropy Method for Analyses of Fluorescence Correlat...

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第一届全国生物物理化学会议暨生物物理化学发展战略研讨会

作者： YIN Yan-Dong,ZHOU Xiao-Xue,ZHAO Xin-Sheng~* beijing National laboratory for {2. Sciences,state key laboratory for structural chemistry of unstable and stable species,and Department of Chemical Biology,college of chemistry and {2. engineering,peking University,beijing 100871,P.R.china

＜正＞It has been a challenge to accurately extract dynamic information from experimental fluorescence correlation spectroscopy（FCS） *** Maximum Entropy Method （MEMExp） which is model-free to fit the exponential f... 详细信息

关键词： Maximum entropy method Fluorescence correlation spectroscopy Oligonucleotides

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