• 제목/요약/키워드: Dendrimers

검색결과 109건 처리시간 0.024초

나노구조 단분자막의 전기적 특성 연구 (A Study of Electrical Characteristics of Nano-Structural Monolayers)

  • 송진원;신훈규;이경섭;최용성
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제55권12호
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    • pp.586-590
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    • 2006
  • Dendrimers represent a new class of synthetic macromoleculcs characterized by a regularly branched treelike structure. Multiple branching yields a large number of chain ends that distinguish dendrimers from conventional star-like polymers and microgels. The azobenzene dendrimer is one of the dendrimeric macromolecules that include the azo-group exhibiting a photochromic character. Due to the presence of the charge transfer element of the azo-group and its rod-shaped structure, these compounds are expected to have potential interest in electronics and photoelectronics, especially in nonlinear optics. In the present paper, we give pressure stimulation to organic thin films and detect the induced displacement current. Functional photoisometrization organic molecular the photo-stimulus to organic monomolecular L films and LB films of dendrimer and 8A5H were performed. The 8A5H organic monolayer in case of pressure stimulus occurred that positive course but in case of the photo-stimulus compared positive and negative. It is assumed that generation forms of displacement current were measured when photo-stimulus for impression.

Biosensing interfaces based on the dendrimer-underlying layer on gold

  • 윤현철;김학성
    • 한국생물공학회:학술대회논문집
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    • 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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    • pp.52-55
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    • 2000
  • Structually organized mono- and multilayers were developed on gold for the catalytic and affinity biosensing using hyper-branched dendrimers. For the catalytic biosensing interface, a new approach to construct a multilayered enzyme film on the electrode surface was developed. The film was prepared by layer-by-layer depositions of dendrimers and periodate-oxidized glucose oxidase. The voltammograms obtained from the GOx/dendrimer multilayered electrodes revealed that bioelectrocatalytic response is directly correlated to the number of deposited bilayers. From the analysis of voltammetric and ellipsometric signals, the coverage of active enzyme per layer during the layering steps was estimated, demonstrating the spatially-ordered multilayer formation. As an extension of the study, dendrimers having various degrees of ferrocenyl modification were prepared and used. The resulting electrodes were electrochemically characterized, and the density of ferrocenyl groups, active enzyme coverage, and sensitivity were estimated. For the affinity-sensing surrface, a biosensor system based on avidin-biotin interaction was developed. As the building block of affinity monolayer, G4 dendrimer having partial ferrocenyl-tethered surface groups was prepared and used. And the biotinylated and electroactive dendritic monolayer was used for the affinity-sensing surface interacting with avidin. Electrochemical characterization of the resulting biosensor was conducted using free enzyme in electrolyte in terms of degree of surface coverage with avidin and subsequent surface shielding.

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다중 모드 SPM을 이용한 덴드리머의 모폴로지 특성에 대한 연구 (Study on Morphological Properties of Dendrimer Using Multi-Mode SPM)

  • 정경한;신훈규;김정균;권영수
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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    • pp.192-195
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    • 2003
  • There has been increasing interest in the applications of synthesized molecules of nanometer scale in recent years due to their potential utilization in various fields such as biology, optoelectronics and molecular electronics. In this study, the terpyridine-platinum (II) complex on the periphery of the dendritic carbosilane has been prepared from the reaction of Pt(COD)Cl2 and the 4'-functionalized-(2,2':6',2"-terpyridine) on dendrimers. The self-assembly process was carried out to obtain indivially dispersed dendrimer on Au (111) substrate. It was found that STM was unsuitable to obtain a obvious image of dendrimers. Tapping-mode atomic force microscopy(AFM) has been used to investigate the shape and size of dendrimers individually dispersed on Au (111)substrate. As a result, the imaged single dendrimer show that dendrimer is dome shaped and its size can be measured by tapping-mode AFM.

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클릭 화학에 의한 폴리(벤질에테르)덴드리머의 효율적인 합성 (Synthesis of Poly(benzyl ether) Dendrimers by Click Chemistry)

  • 이재욱;이언엽;한승철;김지현;진성호
    • 폴리머
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    • 제33권1호
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    • pp.67-71
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    • 2009
  • 프레체형태 덴드리머의 합성을 위한 연결 방법이 알카인기와 아지드기 사이의 클릭 화학을 이용하여 개발되었다. 덴드리머의 핵으로 작용할 수 있는 단위체인 4,4'-(3,5-비스(아지도프로필옥시)벤질옥시)비스페닐이 알카인덴드론과 클릭 반응을 통해 덴드리머의 구축을 위해 사용되었다. 즉, 구리촉매 존재하에서 다중(아지드)화합물과 말단 알킨기를 가지는 폴리(벤질에테르)덴드론 사이치 클릭 반응을 통해 덴드리머의 합성 전략이 완성되었다.

Solvent effect on the excited state of stilbene dendrimers bearing phenylacetylene groups

  • Nishimura, Yoshinobu;Arai, Tatsuo
    • Rapid Communication in Photoscience
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    • 제3권4호
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    • pp.85-87
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    • 2014
  • We studied the characteristics of emissive state of the first (p-G1) and second (p-G2) generation of phenylacetylene dendrimers bearing stilbene as a core by using time-resolved fluorescence spectroscopy in cyclohexane (c-Hex) and N, N-dimethylformide (DMF), which are nonpolar and polar solvents, respectively. Time-dependent red-shift of emission spectra p-G2 both in c-Hex and DMF was observed in comparison with p-G1. Besides, the time constant of red-shift of spectra was found to be larger in DMF than in c-Hex. This indicates that the emissive state of p-G2 has a polar character in DMF as a result of charge delocalization from core to peripheral dendrons followed by stabilization of emissive state.

Theoretically-Guided Optimization of the Electro-Optic Activity of Organic Materials: 300 pm/V and Beyond

  • Sullivan, Phillip;Yiao, Li;Dalton, Larry
    • 한국고분자학회:학술대회논문집
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    • 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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    • pp.11-12
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    • 2006
  • Incorporation of chromophores into multi-chromophore-containing dendrimers is shown to lead to a significant enhancement in electro-optic activity. These results are reasonably well simulated by pseudo-atomistic Monte Carlo calculations that permit dendrimers to interpenetrate (entangle). Calculations also lead to the correct prediction of material densities. An even greater enhancement in electro-optic activity is observed when such dendrimer materials are doped with a second chromophore. This latter effect may reflect an Ising-lattice-type phenomenon where one chromophore impacts the ordering of the other and vice versa.

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Facile Synthesis of Aldehyde-focal Fréchet Type Dendrons and Dendrimers via Staudinger/Aza-Wittig Reactions

  • Han, Seung-Choul;Jin, Sung-Ho;Lee, Jae-Wook
    • Bulletin of the Korean Chemical Society
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    • 제32권10호
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    • pp.3624-3628
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    • 2011
  • Fr$\acute{e}$chet-type dendritic benzaldehydes were efficiently synthesized using 3,5-dihydroxybenzaldehyde as an aldehyde focal point functionalized unit by adding a generation to the existing dendron or direct oxidation of Fr$\acute{e}$chet-type dendritic benzyl alcohols. These dendritic benzaldehydes were applied for the construction of dendrimers containing secondary amines as connectors via Staudinger/aza-Wittig Reactions with ${\alpha}$,${\alpha}'$,-diazidop-xylene core.

Spectrophotometric Determination of Maximum Loading Capacity of a Dendrimer

  • Youngjin Jeon
    • 대한화학회지
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    • 제67권4호
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    • pp.217-221
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    • 2023
  • A series of hydrophobic dodecyl-terminated 6th-generation poly(amidoamine) dendrimer (H)-encapsulated cadmium sulfide ((CdS)n@H) nanoparticles in a co-solvent (toluene: methanol = 6.8: 3.2 v/v) are synthesized. The diameters of CdS nanoparticles within the dendrimer were estimated by analyzing the positions of the first excitonic absorption peaks of CdS in UV-vis spectra. The size of the CdS nanoparticle within the dendrimer shows a saturation value as the CdS/H ratio (n) increases, which is believed to be due to the limited physical size of the void cavity within the dendrimer. This simple and convenient method of estimating the saturation of the size of CdS in dendrimers may be useful in determining the maximum void space within other dendrimers under various solvent conditions.