• Title/Summary/Keyword: Schiff base

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Liquid Crystalline Properties of Schiff Base Mono- and Dimesogenic Compounds (Schiff Base 단일- 및 이메소제닉화합물의 액정성)

  • Park, Joo-Hoon;Choi, Ok-Byung;Lee, Jin-Seok;Kang, Keun-Myoung;Shin, Joo-Cheol;Kim, Ki-Hwan;Kim, Hak-Jin;Lee, Chang-Joon;So, Bong-Keun;Lee, Soo-Min
    • Korean Chemical Engineering Research
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    • v.43 no.1
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    • pp.176-180
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    • 2005
  • The liquid crystalline properties of a series of main chain liquid crystalline polymers and four series compounds consisting of aromatic type Schiff base mesogenic units and polymethylene flexible spacers were studied. The thermal and liquid crystalline properties were investigated by differential scanning calorimetry and on the hot stage of a polarizing microscope. The nature of the liquid crystalline phase of the polymers and compounds depended greatly on the length of the central polymethylene spacer and on the terminal alkoxy groups. Polymers I and Series III exhibited an even-odd effect in melting and isotropization temperatures but Series II and Series IV exhibited an even-odd effect in isotropization temperatures. They formed nematic and smectic mesophases in melts as judged by their optical textures observed through a polarizing microscope.

Studies on the Molybdenum Complexes with Tridentate Schiff Base Ligand (I) (세자리 Schiff Base 리간드의 몰리브덴 착물에 관하여 (제1보))

  • Ki Hyung Chjo
    • Journal of the Korean Chemical Society
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    • v.17 no.3
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    • pp.169-173
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    • 1973
  • The tridentate schiff base ligand, salicyliden amino-o-hydroxy benzene, has derived from salicylaldehyde and o-amino phenol. This ligand reacts with a series of Mo (VI), Mo (V), Mo (IV), and Mo (III) oxidated states and forms a new complexes; [Mo O$_2(H_2O)\;(C_{13}H_9O_2N)]$, [MoO Cl$(H_2O)\;(C_{13}H_9O_2N)]$, [Mo(SCN)$_2(H_2O)\;(C_{13}H_9O2_N)]$$[Mo(H_2O)_2\;(C_{13}H_9O_2N)]_2O$. The Mo (VI), Mo(V) and Mo(Ⅳ) ions in these complexes are octahedron, hexa coordinate, and the mole ratio of these ions to the ligand are 1 : 1, but Mo (III) Complex is a Mo-O-Mo oxygen bridge bond and polynuclear, and the mole ratio of Mo (III) to the ligand 1 : 1 above facts are identified from the data of Infrared spectra, visible spectra, and elemental analysis.

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Synthesis of Tridentate Schiff base Molybdenum(Ⅴ) Complexes and Their Electrochemical Properties in Aprotic Solvents (세자리 Schiff base 몰리브데늄(Ⅴ) 착물들의 합성과 비수용매에서의 전기화학적 성질)

  • Choi, Young-Kook;Song, Mi-Sook;Rim, Chae-Pyeong;Chjo, Ki-Hyung
    • Journal of the Korean Chemical Society
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    • v.39 no.1
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    • pp.47-56
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    • 1995
  • Tridentate Schiff base molybdenum(V) complexes such as [Mo(Ⅴ)2O(SOHB)4], [Mo(Ⅴ)2O3(SOIP)2(NCS)2] and [Mo(Ⅴ)2O3(SOTB)2(H20)2](SOHB: Salicylidene-o-imino hydroxybenzene, SOIP; Salicylidene-o-imino pyridine, SOTB; Salicylidene-o-imino thiolbenzene) were synthesized and identified by elemental analysis, spectroscopy, and thermogravimetric analysis (TGA). It was found that the mole ratio of Schiff base ligand to the metal in these complexes is 1 : 1 or 1 : 2. The redox processes of the complexes were investigated by cyclic voltammetric and differential pulse polarographic techniques in nonaquous solvent containing 0.1 M tetraethylammonium perchlorate (TEAP) as supporting electrolyte at glassy carbon electrode. It was found that diffusion controlled reduction processes with one electron were Mo(Ⅴ)Mo(Ⅴ)e-→ Mo(Ⅴ)Mo(Ⅳ)e-→Mo(Ⅳ)Mo(Ⅳ)e-→Mo(Ⅳ)Mo(Ⅲ).

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Synthesis of Pentadentate Schiff Base Molybdenum(Ⅴ) Complexes and Their Electrochemical Properties in Aprotic Solvents (다섯자리 Schiff Base Molybdenum(Ⅴ) 착물들의 합성과 비수용매에서의 전기화학적 성질)

  • Kim, Seon Suk;Choe, Ju Hyeong;Choe, Yong Guk;Jeong, Byeong Gu
    • Journal of the Korean Chemical Society
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    • v.38 no.2
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    • pp.160-168
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    • 1994
  • Pentadentate Schiff base molybdenum(Ⅴ) complexes such as [Mo(Ⅴ)O(Sal-DET)(NCS)] and [Mo(Ⅴ)O(Sal-DPT)(NCS)] were synthesized by Sabat method. The structure of these complexes were identified by elemental analysis, spectroscopy, and thermogravimetric analysis(T.G.A.). It was found that the mole ratio of Schiff base ligand to the complexes was found to be 1 : 1. The redox processes of the complexes were investigated by cyclic voltammetric and differential pulse polarographic technique in nonaqueous solvent containing 0. 1 M tetraethyl ammonium perchlorate(TEAP) as supporting electrolyte at glassy carbon electrode. It was found that diffusion controlled reduction processes of four steps with one electron were 2Mo(Ⅴ)$\rightleftarrow^{e-}$ Mo(Ⅴ)Mo(Ⅳ) $\longrightarrow^{e-}$ 2Mo(Ⅳ), Mo(Ⅳ) $\longrightarrow^{e-}$ Mo(Ⅲ) $\longrightarrow^{e-}$ Mo(Ⅱ)

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Oxidation Reaction of Hydrazobenzene by Activated Catalysts of Oxygen Adducted Tetradentate Schiff Base Cobalt(Ⅱ) Complexes in Methanol Solvent. (Ⅱ) (메탄올 용매에서 산소 첨가된 네자리 Schiff Base Cobalt(II) 착물들의 활성촉매에 의한 Hydrazobenzene의 산화반응 (제 2 보))

  • Ki-Kyung Chjo;Yong-Kook Choi;Sang-Bock Kim;Jong-Ki Park;Dong-Hwa Park
    • Journal of the Korean Chemical Society
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    • v.36 no.6
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    • pp.894-905
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    • 1992
  • Dioxygen binding and homogeneous catalytic oxidation of hydrazobenzene were investigated by employing tetradentate Schiff base Cobalt(II) complexes such as Co(II)(SED)$(Py)_2$, Co(II)(SOPD)$(Py)_2$ and Co(II)(SND)$(Py)_2$ in saturated oxygen methanol solvent. The major product of hydrazobenzene ($H_2$AB) oxidation by catalysts of superoxo type [Co(III)(SED)(Py)$O_2$] and [Co(III)(SOPD)(Py)$O_2$] complexes are trans-azobenzene (t-AB) and rate constants k for oxidation reaction was 7.692 ${\times}$ $10^{-2}$ M/sec for [Co(III)(SED)(Py)$O_2$] and 5.076 ${\times}$ $10^{-2}$ M/sec for [Co(III)(SOPD)(Py)$O_2$]. But cis-azobenzene (c-AB) are obtained as a major product with ${\mu}$-peroxo type [Co(III)(SED)(Py)]$_2O_2$ catalyst, and rate constant k is 1.266 ${\times}$ $10^{-2}$ M/sec. The rate constants of oxidation reaction has been studied spectrophotometrically and the rate law established. A mechanism involving a intermediate activated complexes of catalyst, hydrazobenzene and oxygen has been proposed. $H_2$AB + Co(II)(Schiff base)$(Py)_2$ + $O_2$ ${\rightleftharpoons}_{MeOH}^K$ Co(III)(Schiff base)(Py)$O_2$${\cdot}$$H_2$AB + Py $\longrightarrow^k$ Co(II)(Schiff base)$(Py)_2$ + t-AB + $H_2O_2$(Scchiff base : SED and SOPD). $H_2$AB + 2Co(II)(SND)$(Py)_2$ + $O_2$ ${\rightleftharpoons}_{MeOH}^K$ [Co(III)(SND)(Py)]$_2O_2$${\cdot}$H_2$AB + 2Py ${\longrightarrow}^k$ (Co(II)(SND)$(Py)_2$ + c-AB + $H_2O_2$.

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Hypsochromic Shifts in Retinochrome Absorption Spectra in the Presence of Nitrate

  • Takemori, Nobuaki;Mizukami, Taku;Tsujimoto, Kazuo
    • Journal of Photoscience
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    • v.9 no.2
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    • pp.264-266
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    • 2002
  • The absorption wavelength of the protonated retinal Schiff base can be controlled by the surrounding environment. An external anion is related to fine adjustment of the absorption wavelength. The addition of anion to retinochrome solution caused blue shift in spectra. The increase of the shift was dependent on the ion concentration. The large shift value was obtained as 20 nm at the saturated concentration of nitrate. The shift intensity for the nitrate addition exceeded that of chloride. Seemingly, it depends on the ionic strength or lyotropic character of the anion. However, neither of sulphate nor gluconate ion showed remarkable blue shift. These phenomena were accounted for with (1) delocalization of the positive charge in the conjugated polyene system, (2) ionic bonding strength between the counter ion (glutamate) and the proton, and/or (3) interaction of the added anion with the proton on Schiff base.

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Electrocatalytic Reduction of Dioxygen at Schiff base Co(II) Complexes supported Glassy Carbon Electrode in various pH Solution

  • Park, Kyoung-Hee;Rim, Chae-Pyeong;Chjo, Ki-Hyung;Jeon, Seungwon;Choi, Yong-Kook
    • Analytical Science and Technology
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    • v.8 no.4
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    • pp.617-622
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    • 1995
  • Electrocatalytic reduction of dioxygen has been investigated by cyclic voltammetry at glassy carbon electrode modified with new Co(II)-Schiff base complexes in aqueous solutions of various pH. The reduction potentials of dioxygen at chemically adsorbed electrodes show the dependence of pH between pH 4 and 14. The catalytic effect is large and the reaction occurs via two or four electron transfer in various pH solution.

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Inorganic polymers of metal (Ⅱ) ions with Schiff's Base of quinizarin-ethylenediamine (Quinizarin-ethylenediamine의 Schiff's Base 와 금속 (Ⅱ) 이온이 만드는 Coordination polymer의 합성에 관하여)

  • Joon Suk Oh;Won Suk Kwak
    • Journal of the Korean Chemical Society
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    • v.13 no.1
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    • pp.29-36
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    • 1969
  • lnorganic polymers, which are composed of metal (Ⅱ) ions and Schiff's Base of quinizarin-ethylenediamine, have been prepared. In order to find out proper conditions for the reaction, some investigations have been carried out to test the effect of pH, kind of solvent and the state of reagent. As a result, the highest yield occurred near pH 7 and it was found that there were not great difference in the kind of solvent and the state of reagent we had used. Most of the polymers are seemed not to be those we have attempted to prepare. They are found to be coordination polymers which have rather low molecular weight.

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