• Title/Summary/Keyword: photo-isomerization

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Measurement of the displacement current induced by the dynamic behavior of monolayer at the water surface. (수면상 단분자박의 거동에 의한 변위전류 측정)

  • Park, T.G.;Park, K.H.;Kwon, Y.S.;Kang, D.Y.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1993.05a
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    • pp.122-125
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    • 1993
  • We investigated the structural changes of the organic molecules of azobenzene-containing long-chain fatty acids which show the cis-trans photo-isomerization characteristics. The dynamic behavior of these polar molecules on the water surface of the Kuhn type LB deposition apparatus was detected electrically by using the displacement current method.

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A Study on the Light Stimulated Transmit of Organic Monolayers (유기 한분자학의 광자극 전달에 관한 연구)

  • 강용철;권영수;조수영;박석순;이경섭
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1996.11a
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    • pp.156-159
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    • 1996
  • Detection of displacement current across spreading organic Azodyes was investigated using a displacement current measuring technique. It was found that displacement current was generated only when dynamical motion of organic monolayers was initiated on the water surface by photo-isomerization and application of surface pressure. Displacement current was generated only in the range before the initial rise of Surface pressures for azo dyes(8A5H) we are using the Langmuir-Blodgett(LB) films deposition apparatus. We are obtain displacement current by pressure and light

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Electrical Properties of 4th generational Dendrimer Containing Azo-group (아조 기능기를 가진 제4세대 덴드리머의 전기적 특성)

  • Yang, Ki-Sung;Ock, Jin-Young;Jung, Sang-Bum;Kim, Chung-Kyun;Park, Jae-Chul;Kwon, Young-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07b
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    • pp.904-907
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    • 2003
  • We synthesized dendrimers containing light switchable units, azobenzene group. To apply to the molecular level devices or data storage system using Langmuir-Blodgett(LB) film, we firstly investigated the monolayer behavior using the surface pressure-area(${\pi}-A$) isotherms at air-water interface. And then the surface pressure shift of monolayer by light irradiation was also measured to the dendrimer with azobezene group. As a result, the monolayer of dendrimer with azobenzene group showed the reversible photo-switching behavior by the isomerization of azobenzene group in their periphery. This results suggest that the dendrimers with azobenzene group can be applied to high efficient nano-device of molecular level. And we measured the electrical properties by MIM and STM. The dendrimer with azobenzene group compared trans form and cis form at electrical properties.

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Photo Displacement Properties of Nano structure Organic Ultra Thin Films (나노구조 덴드리머의 광변위특성)

  • Song, Jin-Won;Choi, Young-Il;Cho, Su-Young;Kim, Deok-Tae;Lee, Woo-Ki;Lee, Kyung-Sup
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11b
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    • pp.23-26
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    • 2004
  • Monolayers of lipids on a water surface have attracted much interest as models of biological membranes, but also as precursors of multilayer systems promising many technical applications. Until now, many methodologies have been developed in order to gain a better understand. Photoisomerization in monolayers of a novel azobenzene compound, azobenzene dendrimer, was investigated for the first time by means of the absorption spectrum and Maxwell displacement current(MDC) technique. Dendrimers are well-defined macromolecules exhibiting a tree-like structure, first derived by the cascade molecule approach According to the absorption spectrum, trans-to-cis conversion ratio was estimated to the third generation of azobenzene dendrimer deposited onto a glass substrate. Temperature-dependent induced charge with trans-cis isomerization was also measured by means of MDC technique.

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Photo Displacement Properties of Nano structure Organic Ultra Thin Films (나노구조 유기초박막의 광변위특성)

  • Song, Jin-Won;Choi, Young-Il;Cho, Su-Young;Kim, Young-Geun;Lee, Kyung-Sup
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11a
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    • pp.468-471
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    • 2004
  • Monolayers of lipids on a water surface have attracted much interest as models of biological membranes, but also as precursors of multilayer systems premising many technical applications. Until now, many methodologies have been developed in order to gain a better understand. Photoisomerization in monolayers of a novel azobenzene compound, azobenzene dendrimer, was investigated for the first time by means of the absorption spectrum and Maxwell displacement current (MDC) technique. Dendrimers are well-defined macromolecules exhibiting a tree-like structure, first derived by the cascade molecule approach. According to the absorption spectrum, trans-to-cis conversion ratio was estimated to the third generation of azobenzene dendrimer deposited onto a glass substrate. Temperature-dependent induced charge with trans-cis isomerization was also measured by means of MDC technique.

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Optical Behavior and Electrical Properties of Functional Dendrimer Thin Films (기능성 덴드리머 박막의 광학적 거동 및 전기적 특성)

  • 박재철;정상범;권영수
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.52 no.5
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    • pp.201-205
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    • 2003
  • We synthesized dendrimers containing light switchable units, azobenzene group. And the dendrimer containing 48 pyridinepropanol functional end group, which could form a complex structure with metal ions was synthesized. To apply to the molecular level devices or data storage system using Langmuir-Blodgett(LB) film, we firstly investigated the monolayer behavior using the surface pressure-area($\pi$-A) isotherms at air-water interface. And then the surface pressure shift of monolayer by light irradiation was also measured to the dendrimer with azobezene group. As a result, the monolayer of dendrimer with azobenzene group showed the reversible photo-switching behavior by the isomerization of azobenzene group in their periphery. The samples for electrical measurement were fabricated to two types which were pure dendrimer with pyridinepropanol group and its complexes with $Pt^4+$ ions by LB method. We have studied the electrical properties of the ultra thin dendrimer LB films investigated by the current-voltage(I-V) characteristics of Metal/Dendrimer LB films/Metal(MIM) structure. And we have investigated different results in the surface activity at the air-water interface as well as the electrical properties for the monolayers of pure dendrimer with pyridinevopanol group and its complex with $Pt^4+$ ions. In conclusion, it is demonstrated that the metal ion around dendrimer with pyri야nepropanol group can contribute to make formation of network structure among dendrimers and it result from the change of electrical properties. This results suggest that the dendrimers with azobenzene group and pvridinedropanol group can be applied to high efficient nano-device of molecular level.

Optical Behavior and Electrical Properties of Functional Dendrimer Thin Films (기능성 덴드리머 박막의 광학적 거동 및 전기적 특성)

  • 박재철;정상범;권영수
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.52 no.5
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    • pp.201-201
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    • 2003
  • We synthesized dendrimers containing light switchable units, azobenzene group. And the dendrimer containing 48 pyridinepropanol functional end group, which could form a complex structure with metal ions was synthesized. To apply to the molecular level devices or data storage system using Langmuir-Blodgett(LB) film, we firstly investigated the monolayer behavior using the surface pressure-area($\pi$-A) isotherms at air-water interface. And then the surface pressure shift of monolayer by light irradiation was also measured to the dendrimer with azobezene group. As a result, the monolayer of dendrimer with azobenzene group showed the reversible photo-switching behavior by the isomerization of azobenzene group in their periphery. The samples for electrical measurement were fabricated to two types which were pure dendrimer with pyridinepropanol group and its complexes with $Pt^4+$ ions by LB method. We have studied the electrical properties of the ultra thin dendrimer LB films investigated by the current-voltage(I-V) characteristics of Metal/Dendrimer LB films/Metal(MIM) structure. And we have investigated different results in the surface activity at the air-water interface as well as the electrical properties for the monolayers of pure dendrimer with pyridinevopanol group and its complex with $Pt^4+$ ions. In conclusion, it is demonstrated that the metal ion around dendrimer with pyri야nepropanol group can contribute to make formation of network structure among dendrimers and it result from the change of electrical properties. This results suggest that the dendrimers with azobenzene group and pvridinedropanol group can be applied to high efficient nano-device of molecular level.

The Identification of Stilbene Compounds and the Change of Their Contents in UV-irradiated Grapevine Leaves (자외선 조사 포도 잎에서 Stilbene 화합물의 동정과 함량의 변화)

  • Choi, Seong-Jin
    • Horticultural Science & Technology
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    • v.29 no.4
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    • pp.374-381
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    • 2011
  • Stilbenes are polyphenolic natural products, which have antioxidative and antifungal activities. In some plants, including grapevine, the stilbene compounds, as resveratrol derivatives, exist in very diverse forms. Experiments to identify the individual stilbene compounds were carried out first to quantify them in UV-irradiated grapevine leaves. For this, stilbene glycosides were extracted from grapevine leaves which irradiated intensively with UV light. The glycoside samples were hydrolyzed by ${\beta}$-glucosidase, before analyzed by HPLC-mass spectrometer at each m/z corresponding to the mass of specific stilbenes. As results, in chromatograms, the enzymatic hydrolysis resulted in decrease and increase of the peaks expected for glycosides and aglycones, respectively. The samples were also exposed to sunlight in order to photo-isomerize the stilbene compounds. The light exposure resulted in disappearance and appearance of peaks expected for trans- and cis-isomers of stilbenes, respectively. Such a change of the peaks in chromatograms provided information needed for the inference to peak components. In this way, it was possible to identify 16 kinds of stilbene compounds from grapevine leaves. The identified stilbenes were quantified from grapevine leaves irradiated mildly by UV light. The UV-irradiation increased markedly in the content of stilbene compounds, especially trans-resveratrol by several hundredfold. In addition, piceatannol, which is a mere minor component of stilbenes in control leaves and a more active radical scavenger than resveratrol, was also increased by several tenfold by the treatment. The increase in stilbene contents as influenced by UV irradiation seems to be one of the stress coping responses of grapevine as a hormesis phenomenon.