IMAGING SCIENCE AND PHOTOCHEMISTRY

SYNTHESIS AND OXIDATION OF N-ALKYLACRIDANS

SONG Huacan, YING Baining, SU Jingyu, GUO Weimin, ZHANG Hongzhong, ZHANG Shaoheng

1997, 15(2): 97-100. DOI: 10.7517/j.issn.1674-0475.1997.02.97

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DISTRIBUTION OF IODIDE AND SULPHUR ATSILVER HALIDE MICROCRYSTAL SURFACE

LI Jinpei, WANG Su’e

1997, 15(2): 101-103. DOI: 10.7517/j.issn.1674-0475.1997.02.101

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Distribution of iodide and sulphur at the surface of cubic silver bromide microcrystal was studied. The observation and determination of which by the methods of STEM and EDS found that the conversion of AgBr to AgI may form high iodide content island at the crystal surface and sulphur sensitization specks prefer to form at this high iodide region. The principle of hard and soft acid and base is applied to analysis this phenomenon.

PHOTOCHEMISTRY OF ARYLMETHYL ESTERS ADSORBED ON ZSM-5 ZEOLITESIZE/SHAPE SELECTIVITY

TONG Zhenhe(TUNG Chenho), YING Yunming, YUAN Longhua

1997, 15(2): 104-108. DOI: 10.7517/j.issn.1674-0475.1997.02.104

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Selectivity in organic photo chemical reactions continues to be one of the main topics of current interest^[1].For the various approaches,the use of constrained and ordered media has shown considerable promise ^[2].Here we illustrate that one can include organic molecules into ZSM-5 zeolite to control the pathways of their photochemical reactions.

INVESTIGATION ON PHOTOINDUCED COLORATION AND MECHANISM OF FLUORANE DYE

ZHOU Wenhui, LIU Jianmin, LI Miaozhen, WANG Erjian

1997, 15(2): 109-113. DOI: 10.7517/j.issn.1674-0475.1997.02.109

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Photoinduced coloration system consisting of fluorane dye(FR) and iodonium salt(DPIOB) was investigated. Upon irradiation, the excited fluorane dye and iodonium salt may undergo electron transfer reaction to form FR_·⁺ and IPh₂^· radical pair, the latter rapidly decomposes to phenyl radical (Ph^·) and iodobenze, and the color form of ring opening ester (FRPh) subsequently is formed by radical coupling between FR_·⁺ and Ph^·. The structure of FRPh possesses good stability, and thus it demonstrates electron transfer reaction is one of effective pathway to improve the color stability of fluoranedye.

INFLUENCE OF ANTIOXIDANT FUNCTIONS OF DRUGS ON KINETICS OF DNA CHEMILUMINESCENCE

ZHANG Jian, CAO Enhua, MA Wenjian, QIN Jingfen, ZHANG Zhonglun, ZHENG Yanzhen

1997, 15(2): 114-119. DOI: 10.7517/j.issn.1674-0475.1997.02.114

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The influence of drugs on chemiluminescence kinetics was observed in CuSO₄ Phen V_C-H₂O₂-DNA chemiluminescent system. Nine natural drugs were studied for their protection against DNA damage and the relationship of drug structure with antioxidant activity was discussed. Three types of antioxidant functions were observed, which indicated that drugs have different functions in different reactions in vivo. In this system, the antioxidant activity of the drugs which depress DNA damage chemiluninescence decreases in the order of ferulic acid、salvianic acid A、rutin、green tea polyphenols、SOD、tans hinone Ⅱ-A、paeonol、γ-schisandrin. The antioxidant activity of the drugs which delay DNA damage chemiluminescence decreases in the order of ferulic acid、rutin、green tea polyphenols、Trolox、salvianic acid A、paeonol. The drugs containing big π conjugated system、hydroxyl group、carboxyl group have relatively great efficiency in depressing DNA damage. This is probably relative to their redox potentials.

DUAL PHOSPHORESCENCE OF BENZOYL S-PHENYL THIOBENZOATES

JIANG Xiaodong, YANG Guoqiang, WU Shikang

1997, 15(2): 120-125. DOI: 10.7517/j.issn.1674-0475.1997.02.120

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The photophysical behavior of S-phenyl thiobenzoates with different substituents has been studied at 77 K and different results were observed. It was found that the only 2-benzoyl derivative can emit dual phosphorescence. This phenomenon was caused by solvent effect. There are at least two conformational isomers existed in polar solution for 2-benzoyl derivative. The peak wavelength in phosphorescence spectrum depends evidently on the excited wavelength used.

PREPARATION AND CHARACTERIZATION OF LB FILMS OF DIAZA-CROWN ETHER CARRYINGTWO CHOLESTERIC UNITS

LI Tiankai, XU Jingmei, ZHAO Wei, JIANG Qing, XIE M ing gui

1997, 15(2): 126-131. DOI: 10.7517/j.issn.1674-0475.1997.02.126

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Monolayer of diaza-crown ether double-armed with cholesteric units was prepared and the surface pressure area curve showed its good and stable film characterization. The case is altogether diffrent from the experimental results of its monoarm liquid crystalline crown ether. UV absorption spectra and low-angle diffraction pattern of multilayer suggested that monolayer could be easily transferred onto substrates to form well organized layered structure with each layer having the same uniform thickness of 2.6 nm. Relating to CPK atomic model, the molecular configuration in LB films was speculated.

STERIC EFFECTS ON THE PROPERTIES OF SENSITIZER

HOU Yuanjun, ZHANG Baowen, CAO Yi, XIAO Xurui, YANG Rong

1997, 15(2): 132-137. DOI: 10.7517/j.issn.1674-0475.1997.02.132

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A new sensitizer named as cis-(NCS)₂-bis(2,2′-bipyridy 1 3,3′-dicarboxylate) ruthenium(Ⅱ) has been prepared, spectroscopically characterized, and anchored to high surface area TiO₂ nanocrystalline electrodes for measuring efficiency of energy conversion. In addition, cis-(NCS)₂-bis(2,2′-bipyridy 1-4,4′-or 5,5′-dicarboxylate) ruthenium(Ⅱ) were prepared by literature methods, and their photophysical and photoelectrochemical properties were measured. From these data, steric effect on the properties of Ru polypyridyl complexes and energy conversion efficiencies has been investigated.

SYNTHESIS OF POLY(ETHYLENE GLYCOL)LINKEDDONOR-ACCEPTOR SYSTEMS AND INVESTIGATION OF INTRAMOLECULAR ELECTRON TRANSFER

LI Shunlai, TIAN Hongjian, ZHOU Qingfu, XU Huijun

1997, 15(2): 138-144. DOI: 10.7517/j.issn.1674-0475.1997.02.138

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A series of electron donor-acceptor system linked by polyethylene glycol have been synthesized. The electron transfer fluorescence quenching of 9-aminoacridin was investigated, efficiencies and rate constants of electron transfer fluorescence quenching have been calculated.

STUDY ON THE BLEACHING OF MONOMERS AND SUBUNITS OF R-PHYCOERYTHRIN BY TRANSITION METALS(Cu²⁺, Cd²⁺)

ZHAO Jiquan, ZHAO Jingquan, ZHANG Jianping, YANG Zixuan, JIANG Lijin

1997, 15(2): 146-150. DOI: 10.7517/j.issn.1674-0475.1997.02.146

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The bleaching of the monomers and the separated α and β subnits of R-phycoery-thrin from Polysiphonia urceolata by Cu²⁺, Cd²⁺, has been investigated. Upon the addition of Cu²⁺ and Cd²⁺, the visible absorption bands of the monomers at 496, 538 and 564 nm of R-phycoerythrin was bleached. The change in absorption induced by Cu²⁺ or Cd²⁺ was accompanied by a decreased fluorescence emission intensity. The bleaching capacity of Cu²⁺ is greater than that of Cd²⁺. When monomers and α subunit are bleached by Cu²⁺, there is no appearance of the characteristic absorption of chromophore complex at 648 nm. But this absorption appeares obviously in the case of β subunit. From above results, we conclude the mechanism is that the bleachng of monomers and α subunit is caused by the interaction of Cu²⁺ or Cd²⁺ with the residues of polypeptides, but β subunit is bleached by both of the interaction of Cu²⁺ or Cd²⁺ with residues of polypeptides and the coordination of Cu²⁺ or Cd²⁺ with chromophores.

THE PHOTODIMERIZATION OF α, ω-BIS(4-METHYLCOUMARIN)TETRAETHYLENEGLYCOL

ZHU Aiping, WU Shikang

1997, 15(2): 152-154. DOI: 10.7517/j.issn.1674-0475.1997.02.152

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The title compound(Ⅰ)containing two coumarin chromophores linked by polyethyleneglycol was synthesized. Its photodimerization process was also studied. The 1HNMR data of compound(Ⅰ)and its dimer(Ⅱ)indicates that the syn head-to-tail dimer is the only regioisomer. The kinetics of dimerization of compound(Ⅰ) was reported.

STUDY OF NUCLEATION OF MONODISPERSE TABULAR GRAIN OF SILVER HALIDE

HU Yongjun, WANG Rongqin, PENG Bixian

1997, 15(2): 155-160. DOI: 10.7517/j.issn.1674-0475.1997.02.155

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he formation of monodispersed hexagonal T grain of silver bromide has been observed and investigated by means of analytical electron microscopy. The morphological observation of the grains shows clearly that: the formation of tabular grain is a gradual evolution process. At the early nucleation stage the grains are spherical, after definite time the spherical grains become tabular. The size distribution indicates that at the nucleation stage two district populations (grain size distribution peaks) appear on the size distribution curve. Between these two peaks there is a critical size. Grains of size being larger than that critical size tend to grow and become tabular, while the others smaller than critical size is apt to desappears or become small. The values of n of silver halide cluster at the early nucleation stage has been estimated and discussed.

PREPARATION, MICROSTRUCTURE, AND PHOTO-ELECTROCHEMICAL PROPERTIES OF POROUS TiO₂ THIN FILM ELECTRODES

WANG Weibo, LI Xueping, XIAO Xurui

1997, 15(2): 161-164. DOI: 10.7517/j.issn.1674-0475.1997.02.161

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Four kinds of different porous TiO₂ thin film electrodes were prepared by spreading and dip-coating methods. Surface morphology and microstructure were characterized by the SEM observations and structural parameters (porosity and surface roughness) determinations. Photocurrent action spectra with front and back side illuminations were used to study the photocurrent behaviours. The results indicate that the spreading TiO₂ thin film electrodes possess porous structure and different photocurrent behaviours compared with that of dip-coating TiO₂ thin film electrodes. The photoelectrochemical properties of spreading TiO₂ thin film electrodes can be improved by optimizing the film thickness and sintering temperature.

SYNTHESIS OF STARBURST HYPERBRANCHEDPOLYESTERS AND THEIR PHOTOCURING

SHI Wenfang

1997, 15(2): 165-168. DOI: 10.7517/j.issn.1674-0475.1997.02.165

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The divergent synthesis of a series of polydisperse hyperbranched polyesters based upon pentaerythritol and 1,2,4 benzenetricarboxylic anhydride, modified by glycidyl methacrylate and methacrylic anhydride, are described, proceeding in a stepwise growth manner starting from an “initiator core”, building starburst branched arms. The photocuring characteristics of these hyperbranched polyesters and thermal mechanical properties of the UV cured films, such as glass transition temperatures and pendulum hardness etc., have been studied.

STUDY ON MULTISTRUCTURE SILVER BROMOIODILE EMULSION GRAINS

WANG Wei, PENG Yanbin, YU Qing, MA Fengyun, ZHOU Benmao, SHEN Shouyao, LIU Qize, CHENG Haichang

1997, 15(2): 169-173. DOI: 10.7517/j.issn.1674-0475.1997.02.169

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Cubic multistructure silver bromoiodide emulsion grains with iodide-rich layer between core and cover were studied with TEM, XRD and XPS. TEM, XRD analysis showed: the iodide-rich layers were composed of AgBr_0.83I_0.17 and AgBr_0.71I_0.29 when precipitated at pAg_5.7 and 8.7 respectively. Iodide rich layer did not cover the whole core, instead, they precipitated only near the comers of the cubic core grains. XPS analysis showed that the surface of the multistructure grain contained iodide though we added only Ag + and Br. To make the cover, the iodide concentration of the surface elevated with increased qnantity of iodide-rich phase.

POLYION COMPLEXES BASED ON DIASO-RESIN

CAO Weixiao, YE Shujian, CAO Shuguang, ZHAO Chao

1997, 15(2): 174-177. DOI: 10.7517/j.issn.1674-0475.1997.02.174

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Polyion complexes based on diazo-resin were prepared from the reaction between diazo-resin as polycation and poly(sodium 4-styrene sulfonate) as polyanion in aqueous solution. The polyion complexes containing diazonium groups exhibit high photosensitive behaviors. Under irradiation of UV light, the complex, which dissolves in the shielding solvent composed of DMF-H₂O LiCl, will become indissoluble because the complex changes its crosslinking structure from ionic link to covalent bond. This character should be very important to develop a new photoimaging system.

SPECTRAL AND PHOTOCHEMICAL PROPERTIES OF XANTHENE DYE-BIS(DIPHENYL IODONIUM)SALTS IN POLYMER FILM

ZHOU Wenhui, LI Miaozhen, ZHOU Hua’e, WANG Erjian

1997, 15(2): 178-182. DOI: 10.7517/j.issn.1674-0475.1997.02.178

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The spectral and photochemical properties of eosin bis(diphenyl iodonium)salt and rose bengle bis(diphenyl iodonium) salt in polymer film have been studied. Their absorption spectra show a red-shift compared with those in solution and the peaks of dimers at long wavelength appear in the high XT(IPh₂)₂ concentration in the film. Upon irradiation with visible light, XT(IPh₂)₂ salts undergo electron transfer to generate leuco of dye, active phenyl radicals and iodobenzene. Owing to restriction of molecular movement in solid film, the photobleaching rates of xanthene dye anions bonded to iodonium cations(XT(IPh₂)₂) are much higher than those of two components system (XT(NEt₄₄)₂/IPh₂BF₄).

1997, 15(2): 183-187. DOI: 10.7517/j.issn.1674-0475.1997.02.183

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1997, 15(2): 188-192. DOI: 10.7517/j.issn.1674-0475.1997.02.188

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