• Analytical Science and Technology
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• v.19 no.4
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• pp.309-315
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• 2006

Two piperazine-templated metal sulfate complexes, $(C_4N_2H_{12})[Ni(H_2O)_6](SO_4)_2$, I and ($C_4N_2H_{12}$) $[Co(H_2O)_6](SO_4)_2$, II, have been synthesized by hydro/solvothermal reactions and their crystal structures analyzed by single crystal X-ray diffraction methods. Complex I crystallizes in the monoclinic system, $P2_1/n$ space group, a=12.920(3), b=10.616(2), $c=13.303(2){\AA}$, ${\beta}=114.09(1)^{\circ}$, Z=4, $R_1=0.030$ for 3683 reflections; II: monoclinic $P2_1/n$, a=12.906(3), b=10.711(2), $c=13.303(2){\AA}$, ${\beta}=114.10(2)^{\circ}$, Z=4, $R_1=0.032$ for 4010 reflections. The crystal structures of the piperazine-templated metal(II) sulfates demonstrate zero-dimensional compound constituted by diprotonated piperazine cations, metal(II) cations and sulfate anions. The structures of complex I and II are substantially isostructural to that of the previously reported our piperazine-templated copper(II) sulfate complex $(C_4N_2H_{12})[Cu(H_2O)_6](SO_4)_2$. The central metal(II) atoms are coordinated by six water molecules in the octahedral geometry. The crystal structures are stabilized by three-dimensional networks of the $O_{water}-H{\cdots}O_{sulfate}$ and $N_{pip}-H{\cdots}O_{sulfate}$ hydrogen bonds between the water molecules and sulfate anions and protonated piperazine cations. Based on the results of thermal analysis, the thermal decomposition reactions of the complex I was analyzed to have three distinctive stages whereas the complex II proceed through several stages.

• Bulletin of the Korean Chemical Society
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• v.18 no.10
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• pp.1061-1066
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• 1997

The complexes M(CO)4-1,2-(PPh2)2-1,2-C2B10H10 (M=Cr 2a, Mo 2b, W 2c) have been prepared in good yields from readily available bis-diphenylphosphino-o-carboranyl ligand, closo-1,2-(PPh2)2-1,2-C2B10H10 (1), by direct reaction with Group Ⅵ metal carbonyls. The infrared spectra of the complexes indicate that there is an octahedral disposition of chelate bis-diphenylphosphino-o-carboranyl ligand around the metal atom. The crystal structure of 2a was determined by X-ray diffraction. Complex 2a crystallizes in the monoclinic space group P21/n with cell parameters a = 12.2360(7), b = 17.156(1), c = 16.2040(6) Å, V = 3354.1(3) Å3, and Z =4. Of the reflections measured a total of 2514 unique reflections with F2 > 3σ(F2) was used during subsequent structure refinement. Refinement converged to R1 = 0.066 and R2 = 0.071. Structural studies showed that the chromium atom had a slightly distorted pseudo-octahedral configuration about the metal center with two phosphine groups of o-carborane occupying the equatorial plane cis-orientation to each other. These metal carbonyl complexes are rapidly converted to the corresponding metal carbene complexes, [(CO)3M=C(OCH3)(CH3)]-1,2-(PPh2)2-1,2-C2B10H10 (M= Cr 3a, Mo 3b, W 3c), via alkylation with methyllithium followed by O-methylation with CF3SO3CH3.

• Journal of the Korean Chemical Society
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• v.20 no.1
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• pp.35-42
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• 1976

Amine salts of five tetrahedral and three octahedral oxalatoferrate(Ⅲ) complexes have been prepared including pyridinium salts of unreported oxalate complex ions $[FeC_2O_4Br_2]^-,$ $[FeC_2O_4(NCS)_4]^{3-}$ and $[Fe_2(C_2O_4)_3Cl_4]^{4-},$ the latter being most photoreactive. The structural aspects of these new complex ions as well as of other oxalatoferrates(III) have been discussed based on their analytical data and infrared spectra. The results of molar conductivity and magnetic susceptibility measurements of all these oxalatoferrate(III) complexes were also presented.

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.37-52
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• 2013

무어의 법칙에 따르면, 반도체의 집적도 2년마다 2배씩 증가한다고 한다. 무어의 법칙은 지금까지는 집적회로 기술의 발전을 잘 예측했다. 하지만 트랜지스터의 사이즈를 줄일수록 누수전류와 회로의 저항을 조절하기 어렵기 때문에 트랜지스터의 소형화에는 한계가 있다. 우리는 곧 무어의 법칙의 한계를 맞이할 것이다. 그래서 트랜지스터를 더욱 소형화시키기 위해서는 bottom-up analysis가 필요한 시점이다. Top-down analysis가 초기의 커다란 트랜지스터에서 점점 소형화를 시켜 작은 트랜지스터를 만든다는 개념인 반면, Bottom-up analysis는 처음부터 작은 분자를 조작하여 트랜지스터와 같은 성질을 띄도록 만드는 개념이다. 분자가 기억소자로서 이용되려면 저항이 다른 2가지 안정한 상태가 필요하다. 이번 연구에서 나는 기억소자를 디자인 하기 위하여 high spin state와 low spin state 두 가지 안정한 상태를 가지는 spin crossover complex를 이용하기로 했다. 이전의 연구에서 spin crossover 는 전기장을 이용해서도 유도될 수 있다고 확신하였고, 이를 이용해서 기억소자를 디자인하기로 하였다. 이번 연구를 위해서 symmetry를 가지는 octahedral spin crossover complex를 디자인하였고 이를 '기억 분자'라고 명명했다. 그리고 이 분자의 high spin state와 low spin state가 전기장을 이용하여 서로 바뀔 수 있는지 가능성을 DFT with B3LYP functional을 이용해서 비교했다. 그 결과로 전기장을 이용하여 기억분자의 spin crossover을 일으킬 수는 있지만 abnormally strong electric field를 써야 한다는 사실을 알아냈다. 이번 연구를 토대로 추후의 연구를 위해, 기억소자가 되기 위하여 분자가 어떤 특징을 만족시켜야 하는지를 분석했다.

• Journal of the korean Society of Automotive Engineers
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• v.8 no.1
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• pp.40-51
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• 1986

A study has been made of the corrosion fatigue of high strength low alloy steel in 3.5% NaCl solution under tension stress for solution temperature being 25.deg. C, 55.deg. C and 85 .deg. C. The main results obtained are as follows; 1) The corrosion fatigue crack growth rate curve could be divided into the First Region, the Second Region and the Third Region. 2) The corrosion fatigue crack growth rates in the First Region and the Second Region were Arrhenius temperature-dependent in this test range. The apparent activation energies for the corrosion fatigue cack growth rate were found to be 2000cal/mol in the First Region and 3700 cal/mol in the Second Region. 3) Hematite (Fe$_{2}$O$_{3}$) as the hexahedral crystal and magnetite (Fe$_{3}$O$_{4}$) as the octahedral crystal were observed in the corrosion products on the corrosion fatigue fracture surface at 85.deg. C and the anode fusion seem to be generated in the crack tip region at high temperature. 4) The complex environment effect ratio which was defined by the ratio of fatigue crack growth rate in corrosion environment to that in air might be considered not only a criterion estimating the effect of environment quantitatively but also an important parameter in the selection of the design stress for the fail safe design. The complex environment effect was not greater than ten in this test.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.4
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• pp.318-324
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• 1983

Electrochemical properties of Georgia kaolinite in aqueous suspension were studied by ion adsorption, potentiometric titration, and electrophoretic mobility measurements. Kaolinite in 0.001 M and 0.1 M NaCl solution showed qualitatively both pH independent and pH depender negative and positive charges through pH range 2.5-11.0 when dissolved aluminum ions from kaolinite were considered as well as $Na^+$ and $Cl^-$ as index ions. Electrophoretic mobilities (EM) of 0.02 wt. % kaolinite suspension in distilled water and 0.001 M NaCl solution were approximately constant against mobility measuring time consumed in the electrophoresis cell at different pH values, and isoelectric points(IEP) were around pH 4.7. EM values in 0.1 M NaCl solution were positive and constant against mobility measuring time below pH 4; but above pH 4, EM values were negative for the first 10 seconds followed by positive values which became approximately constant through stepped changes after 10 minutes. Hydrated cations may bind to the six- member oxygen ring sites having multiple partial negative charges on the exterior tetrahedral layer surface by both electrostatic and hydrogen bonding force while hydrated anions bind to the partially positively charged hydrogen atoms on the exterior octahedral layer surface. Parts of the aluminol groups on the exterior octahedral layer surface as well as edge faces may be involved in complex reactions and have both anion and cation exchange capacities in the electrolyte solution above pH 4.

• Journal of the Korean Chemical Society
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• v.24 no.5
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• pp.356-360
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• 1980

Octahedral Co(Ⅲ) complexes of the glycine methyl ester have been prepared and characterized by elemental analysis, infrared, and NMR spectrum. Co(Ⅲ) glycine methyl ester complex has been isolated from the reaction of glycine and glycine methyl ester in aqueous solution by cation exchange resin, Dowex 50W-X8 (hydrogen form). It has been observed that the complexes have $C_1-cis(0-0), C_2-cis(0-0), trans(0-0)$ geometry.

• 한국지구물리탐사학회:학술대회논문집
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• 2009.10a
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• pp.107-109
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• 2009

Micromagnetism explores magnetic configurations in nano-scales to visualize the details of magnetic domain structures, and also can produce snapshots of complex remanence or other magnetic states. The particle shape has a profound effect on the magnetic hysteresis. For instance, octahedral magnetite showed higher coercivity and squareness than cubic magnetite.

• Journal of the Korean Ceramic Society
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• v.26 no.2
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• pp.276-288
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• 1989

Interpretation of high-resolution transmission electron microscopy images of defects and complex structures such as found in ceramics generally requires matching of the images with compound image simulations for reliable interpretation. A transmission electron microscopy study of the aluminum oxide was carried out at high-resolution, so that the crystal structure of the aluminum oxide could be modelled on an atomic level. In conjunction with computer simulation comparisons, the images reveal directly the atomic structure of the oxide. Results show that comparison between experimental high-resolution electron microscopy images and simulated images leads to a one to one correspondence of the image to the atomic model of the aluminum oxide. The aluminum atoms are disordered in the octahedral sites and the tetrahedral sites in the spinel aluminum oxide.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.1004-1013
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• 2010

Three-dimensional superstructures of unique self-assemblies generated by exploring the conformational flexibility of various dipyrromethenes through creation of hydrogen-bonds with metal-halide anions are reported and the conformational diversity is thoroughly described in the solid and solution states by X-ray diffraction analysis and variable temperature NMR spectroscopy. The tetrahedral or octahedral structures of their precursors, various metal-dipyrromethene complexes, are also reported, based on the crystallographic data. STM images of the self-assemblies observed on graphite surfaces present interesting arrangements and appear as tubular bunches.