IMAGING SCIENCE AND PHOTOCHEMISTRY

FLUORESCENCE AND PHOTODIMERIZATION OF A CALIX[4] ARENE-BASED 2-NAPHTHOATE

JI Haifeng, TONG Zhenhe(TUNG Chenho)

1996, 14(4): 289-292. DOI: 10.7517/j.issn.1674-0475.1996.04.289

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Calix[4] arenes are cyclic oligomers made up of phenol units bridges. They have found wide use as building blocks for constructing linked by methylene novel host molecules in supramolecular chemistry owing to their cavity-shaped structure^[1,2].

THE SUPER SENSITIZATION OF HYDROXY-TETRAAZAINDENE IN SILVER CHLORIDE EMULSION

ZHENG Junping, CHEN Ping, ZHANG Li, ZHENG Deshui

1996, 14(4): 293-297. DOI: 10.7517/j.issn.1674-0475.1996.04.293

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The sensitization of AgCl emulsion by hydroxy-tetraazaindene and the relationship between photographic properties of the emulsion and its spectral absorbance have been investigated. The results indicated that sensitivity of spectral-sensitized emulsion could be increased by hydroxy-tetraazaindene, namely, supersensitization take place, and at the same time,fog of emulsion also be inhibited. It is also found that the adding order of dye and hydroxytetraazaindene has exceedingly effect on the photographic property. By the reflection spectra and the ESR experiment, it is suggested that there is relationship between sensitivity of emulsion and the formation of aggregate of dye on the emulsion grains and the amount of light induced dye positive hole.

STUDY ON THE CHARACTERS OF PHOTOLYSIS OF DIMETHYL SULFIDE

YANG Wenxiang, ZHONG Jinxian, MU Yijing, WANG Suxing, CHEN Dazhou

1996, 14(4): 298-305. DOI: 10.7517/j.issn.1674-0475.1996.04.298

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The dimethyl sulfide(DMS) was irradiated by UV in the absence or presence of O₂ and H₂O₂.The products of photolysis were detected by a Fourier Transform Infrared Spectroscopy equipped with a 20m long path cell. The results indicate that the C─S bond of DMS could be broken in the absence of O₂. As a result, CH₃SSCH₃ and CH₃CH₃ compounds were formed. In the case of presence of O₂ in the system,CH2O and CH₃SO_H could be formed. If H₂O₂ presents in the system, the products of photolysis of DMS would be CH₃SO₃H and CH₃SSCH₃. The mechanism of photolysis of DMS has been discussed. According to this mechanism, the formation of products can be explained.

THE INFLUENCE OF CYCLODEXTRIN ON THE PHOTOPHYSICAL PROPERTIES OF α,ω-BISCOUMARIN LONG-CHAIN COMPOUNDS

LIU Tianjun, WU Shikang

1996, 14(4): 306-313. DOI: 10.7517/j.issn.1674-0475.1996.04.306

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With the aids of different spectra and the single photon counting technique,the effect of concentration,temperature, and environment on the excimer formation of α,ω-biscoumarin long chain compound in the presence of CD have been investigated in this work.Results indicate that the influence of cyclodextrin on the photophysical properties of title compounds is different,i.e.,β-CD only enhances the fluorescence intensity of the coumarin monomer, whereas γ-CD could decrease the activation energy for the excimer formation as well as extend its life time.

STUDY ON THE MECHANISM OF PHOTOOXIDATION OF NEAR-INFRARED ABSORBING CYANINE DYES

LIJun CHEN Ping, ZHAO Jiang, ZHENG Deshui, TSUNEKI Okazaki, MASAAKI Hayami

1996, 14(4): 314-319. DOI: 10.7517/j.issn.1674-0475.1996.04.314

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In this paper,spectrum characteristic and stability of three near-infrared cyanine dyes against photooxidation have been studied. Results showed that the stability of dyes with three kinds typical structure of heterocyclic stem against photooxidation was in such order:benzoxazole>benzothiazole>benselenazole. It was indicated through the quenching experiments that both of singlet oxygen mechanism and superoxide anion mechanism might be present in the auto-sensitized photooxidation of cyanine dyes, and photooxidation merely occurred in single oxygen mechanism.

A COMPARISON BETWEEN THE BEHAVIOR OF THE LIGHT INDUCED ELECTRON AND REDUCING AGENT ELECTRON IN THE SILVER HALIDE GRAINS

XIA Yunyong, ZHUANG Siyong, LIU Fengshan

1996, 14(4): 320-324. DOI: 10.7517/j.issn.1674-0475.1996.04.320

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The behavior of the light induced electron and the reducing agent electron in direct positive emulsions was studied. The locations of the fog centers preferably formed in the grain introduced by light are different from those introduced by reducing agents. When photofogged the fog centers are formed in the interior of the grain first indicating that the light induced electrons can enter the conduction band directly. Wherease, when fogged by reducting agents, the internal fog centers are formed only when the quantity of reducing agent is sufficient and after the formation of surface centers. In above two cases the ways in which electrons enter the conduction band of silver halide are different.

THE EFFECTS OF GOLD IN THE PRE-FOGGING PROCESS OF DIRECT POSITIVE EMULSIONS

XIA Yunyong, ZHUANG Siyong, LIU Fengshan

1996, 14(4): 325-330. DOI: 10.7517/j.issn.1674-0475.1996.04.325

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Gold plays a very important rule in the pre-fogging process of the direct positive emulsion. In this paper the effects of gold on the formation of fog centers were studied by adding silver halide solvents after the emulsions were fogged by thiourea dioxide and thiourea dioxide plus gold, respectively. The interaction between the gold and the fog centers was studied by alternatively immersing in the gold bath and sodium cyanide bath. The results indicate that the presence of gold when fogged can make the fog center size distribution narrow. It is also shown that the deposition of gold is the main reaction when there are plenty of reduction agent in the emulsion layer and the replacement of silve atomes by gold may become important when there is short of reduction agent.When the direct positve emulsion is pre-fogged,the reduction of gold ions and the deposiotion of gold onto the fog centers is the main reaction, because there is plenty of reduction agent.

SYNTHESIS OF SEMICONDUCTOR NANOPARTICLES IN REVERSE MICELLES AND MICROHETEROGENEOUS ELECTRON-TRANSFER FROM PYRENE TO THESE PARTICLES

ZANG Ling, LIU Chunyan, ZHAO Jincai, REN Xinmin, SHEN Tao, HISAO Hidaka

1996, 14(4): 331-340. DOI: 10.7517/j.issn.1674-0475.1996.04.331

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Semiconductor nanoparticles of CdS and ZnS have been synthesized in AOT-isooctane reverse micelles. It was found that the fluorescence quantum efficiency of the semiconductor particle decreases with increasing water content. This is attributed to the dilution of Cd²⁺ or Zn²⁺ ions at the interface of semiconductor particles. These cations favor the formation of sulfur vacancy, where the radiation recombination of the electron-hole pair occurs. The fluorescences of CdS and ZnS particles are effectively quenched by the addition of Ag⁺ ions.Such a process can be described by the Poisson statistics for the distribution of AG+ ions in reverse micelles. An efficient microheterogeneous electron-transfer was observed from pyrene to the CdS particles formed in AOT-isooctane reverse micelles,whereas no electrontransfer can be observed at ZnS particles. This is explained with considering the relative positions of the conduction bands of CdS and ZnS particles with respect to the oxidation potential of the excited singlet of pyrene. Adsorption of Cu²⁺ and Ag⁺ ions on the ZnS particle leads to the formation of mixed semiconductor particles, Cu_x-Zn_1-xS and Ag_2xZn_1-xS, the conduction bands of which are adjusted between those of ZnS and CuS or Ag₂S. Electrons can be injected from pyrene to these mixed particles. The efficiency of the electron-transfer is determined by the probability of the contact of pyrene with the semiconductor particles.

STUDY ON AXIAL COORDINATION REACTION FOR COBALT TETRASULFONATE PHTHALOCYANINE

YUAN Shihai, WU Xing, YAO Rong, Zheng Gang

1996, 14(4): 341-346. DOI: 10.7517/j.issn.1674-0475.1996.04.341

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The coordination reaction for formation of a complex CoTSPc(L)₂ which was formed by cobalt tetrasulfonate phthalocyanine(CoTSPc) plus ligand L(L=NH₃、CN^-、en) was studied by spectrophotometric method. The reaction kinetics of CoTSPc(L)₂ formation has been discussed and the stability constant K of CoTSPc(L)₂ was also calculated from absorbance measurement. The results show that the kinetic equations of CoTSPc(L)₂ formed by COTSPc and L are as follows: -dC_M/dt=kC_MC_Lⁿ where n=1 for en and n=2 for NH₃ or CN,CM and C_L are concentration of CoTSPc and ligand respectively. The stability constant of CoTSPc(L)₂ is lgK=4. 630 for L=en, lgK=5. 328 for L=NH₃, and lgK=9. 116for L=CN^-, respectively.

STUDY ON CHARGE TRANSFER SPECTRA AND OXIDIZATION OF 10,10’-DIALKYL-9,9’-BIACRIDENS

SONG Huacan, PAN Wenlong, Ying Baining, SU Jingyu

1996, 14(4): 347-350. DOI: 10.7517/j.issn.1674-0475.1996.04.347

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Acridine derivatives,e. g. amsacrine^[1] and antimicrobial^[2,3] drugs,are known as anticancer drugs from the point of view of biology and 10,10’-dialkyl-9,9’-biacridinium nitrates are called lucigenin which were used as reagent in chemical analysis^[4,5] The solutions of 10. 10’-dialkyl-9,9’-bialkylacridens have strong fluorescence and it is found that the bialkylacridens can be oxidized easily by the air,so they may be used der to investigate the charge donation ability of the biacridens,ten 10,10'-dialkyl-9,9'-biacridens were synthesized by the reduction of corresponding N-alkylacridones with Zn powder and hydrogen chloride and ethyl alcohol.

STUDIES ON PHOTOOXIDATION Ⅸ.PHOTOOXIDATION OF N-BENZYLIDINE-N-TERT-BUTYLIMINE

WU Shuping, JIANG Zhiqin, JIA Farei

1996, 14(4): 351-354. DOI: 10.7517/j.issn.1674-0475.1996.04.351

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The self and sensitized photooxidation of imines,N-benzylidine-N-tert-butylimine(BBI) and N^- phenyl-N-diphenylmethyleneimine(PDPMI), were investigated. It was found that BBI underwent a facile photooxidation. The reaction product distribution of BBI was determined, indicating oxidation-clevage mechanism may be involved. In contrast,PDPMI showed low reactivity to photooxidation.

THE FLUORESCENCE SPECTRA AND LIFETIME OF NOVEL BICHROMOPHORIC DYES

TIAN He, SU Jianhua, CHEN Kongchang, ZHANG Zhenpin, GUO Mengxin

1996, 14(4): 355-359. DOI: 10.7517/j.issn.1674-0475.1996.04.355

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Novel bichromophoric rhodamine dyes,in which carbazole chromophore was connected with rhodamine 6G or rhodamine DR-21 by -CH₂CH₂-,have been synthesized.The absorption and fluorescence spectra of these bichromophoric dyes have been measured. The absorption of the bichromophoric dyes is the sum of that of two chromophores alone.A lot of fluorescence emission of carbazole in the bichromophoric dyes was quenched. The fluorescence lifetimes of the dyes have been measured by single-photon counting technique. The fluorescence lifetime of carbazole is shortened obviously in the bichromophoric dyes(from 15.4 ns reduced to about 7.8ns). The intramolecular energy transfer and charge transfer between two chromophores have been discussed.

1996, 14(4): 360-364. DOI: 10.7517/j.issn.1674-0475.1996.04.360

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1996, 14(4): 365-373. DOI: 10.7517/j.issn.1674-0475.1996.04.365

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1996, 14(4): 374-374. DOI: 10.7517/j.issn.1674-0475.1996.04.374

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