• Title/Summary/Keyword: Bridging complex.

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New Types of Constrained Geometry Catalysts Containing Silacycloalkyl Bridging Unit: Synthesis, Structure, and Polymerization Activity

  • Ok, Myung-Ahn;Hahn, Jong-Sok;Jung, Jae-Ho;Kang, Sang-Ook
    • Proceedings of the Polymer Society of Korea Conference
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    • 2006.10a
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    • pp.222-222
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    • 2006
  • New types of constrained geometry complexes comprising rigid silacycloalkyl group incorporated into the bridging position between cyclopentadienyl and amido functionalities were prepared. The catalytic activities of olefin polymerization were influenced by the change of exo-cyclic ring size on bridge-head silacycloalkyl unit. It has been noted that the activities of this unique series increase with increasing size of the silacycloalkyl bridge and reach the maximum in six-membered silacyclohexyl-bridged CGC complex. It is noteworthy that conformation of silacycloalkanes gives rise to enhanced catalytic activity of the titanium center although the cyclic ring and titanium center are far remoted from each other.

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Korean Pharmacogenomic Database: Pharmacogenomic Haplotype Analysis of the Korean Population and Ethnic Comparisons

  • Kang, Tae-Sun;Woo, Sun-Wook;Park, Hyun-Joo;Roh, Jae-Sook
    • Biomolecules & Therapeutics
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    • v.16 no.2
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    • pp.77-81
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    • 2008
  • The major aim of the Korean Pharmacogenomic Database (KPD) is to offer to users a "bridging" function, making the search for useful information easier. This database has also been established to collect unique Korean genotype data from other databases and to directly link these data to other major databases that offer more informative data. In this way, searches for information about new drug developments and easier and faster evaluation of the more complex and larger databases are possible. The KPD is located at the National Institute of Toxicological Research homepage (http://www.nitr.go.kr/nitr/contents/m134700/view.do), and offers Korean single-nucleotide polymorphism (SNP) information for 154 genes and haplotype information. It also compares the Korean SNP and haplotype frequencies with those of the other ethnic groups registered in the International HapMap. Through the Pharmacogenomic Information and Education facility, we also provide evaluators and the public with information about the concept of pharmacogenomic information, research trends, and the drug regulations of other countries. Because the drug responses of Koreans are not necessarily the same as those of Chinese or Japanese people, it is expected that the systematic operation of the KPD will allow the definition of racial differences and various genomic biomarkers (haplotypes or SNPs) for use in bridging studies and in the approval of new drugs.

Synthesis and Reactivity of Dinuclear Ni(II) Azido Complexes Containing Bithienylene or Terthienylene Bridging Ligands

  • Kim, Yong-Joo;Lee, Hyuck-Hee;Zheng, Zhen Nu;Lee, Soon-W.
    • Bulletin of the Korean Chemical Society
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    • v.32 no.9
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    • pp.3239-3244
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    • 2011
  • Dinuclear Ni(II)-thiophene halides, which contain linear bridging thienylenes, trans,trans-[$(PR_3)_2$(X)Ni-Y-Ni(X)$(PR_3)_2$] {X = Cl, Br; $H_2Y$ = 5,5'-dichloro-2,2'-bithiophene ($H_2bth$); $H_2tth$ = 5,5"-dichloro-2,2':5',2''-terthiophene ($H_2tth$)} were prepared by the oxidative addition of dihalobithiophene ($H_2bth$) or dihaloterthiophene ($H_2tth$) to [$Ni(COD)_2$] in the presence of tertiary phosphines. Subsequent reactions of $NaN_3$ with the dinuclear Ni(II)-thiophene chlorides gave the corresponding Ni(II)-azido complexes, trans,trans-[$(PR_3)_2(N_3)$Ni-Y-Ni$(N_3)(PR_3)_2$], whose reactivity toward trimethylsilyl pseudohalides such as trimethylsilyl isothiocyanates and cyanides was investigated. In addition, the reaction of trans-[$BrNi(PEt_3)_2-C_4H_2S-C_4H_2S$-CHO], a thienyl Ni(II) complex containing a terminal aldehyde group, with phosphonium ylide was examined.

Solution Dynamics and Crystal Structure of $CpMoOs_{3}(CO)_{10}(\mu-H)_{2}[\mu_{3}-\eta^{2}-C(O)CH_{2}Tol]$

  • Joon T. Park;Jeong-Ju Cho;Kang-Moon Chun;Sock-Sung Yun;Kim SangSoo
    • Bulletin of the Korean Chemical Society
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    • v.14 no.1
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    • pp.137-143
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    • 1993
  • The tetranuclear heterometallic complex CpMo$Os_3(CO)_{10}({\mu]-H)2[{\mu}3-{\eta}^2-C(O)CH_2Tol]\;(1,\;Cp={\eta}^5-C_5H_5,\;Tol=p-C_6H_4Me)$ has been examined by variable-temperature $^{13}$C-NMR spectroscopy and by a full three-dimensional X-ray structual analysis. Complex 1 crystallizes in the orthorhombic space group Pna2$_1$ with a = 12.960(1) ${\AA}$, b = 11.255(l) ${\AA}$, c = 38.569(10)${\AA}$, V = 5626(2) ${\AA}^3$ and ${\rho}$(calcd) = 2.71 gcm$^{-3}$ for Z = 8 and molecular weight 1146.9. Diffraction data were collectedon a CAD4 diffractometer, and the structure was refined to $R_F$ = 9.7% and $R_{W^F}$ = 9.9% for 2530 data (MoK${\alpha}$ radiation). There are two essentially equivalent molecules in the crystallographic asymmetric unit. The tetranuclear molecule contains a triangulated rhomboidal arrangement of metal atoms with Os(2) and Mo at the two bridgehead positions. The metal framework is planar; the dihedral angle between Os(l)-Os(2)-Mo and Os(3)-Os(2)-Mo planes is 180$^{\circ}$. A triply bridging (${\mu}_3,\;{\eta}^2$) acyl ligand lies above the Os(l)-Os(2)-Mo plane; the oxygen atom spans the two bridgehead positions, while the carbon atom spans one bridgehead position and an acute apical position. The molecular architecture is completed by an ${\eta}^5$-cyclopentadienyl ligand and a semi-triply bridging carbonyl ligand on the molybdenum atom, and nine terminal carbonyl ligands-four on Os(3), three on Os(l), and two on Os(2). The two hydride ligands are inferred to occupy the Os(l)-Os(2) and Mo-Os(3) edges from structural and NMR data.

Tetrameric Self-Assembly of a Cu(II) Complex Containing Schiff-Base Ligand and Its Unusually High Catecholase-like Activity

  • Sarkar, Shuranjan;Lee, Woo Ram;Hong, Chang Seop;Lee, Hong-In
    • Bulletin of the Korean Chemical Society
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    • v.34 no.9
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    • pp.2731-2736
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    • 2013
  • We report a new tetrameric supramolecular Cu(II) complex ($Cu_4L_4$ = tetrakis(N,N'-bis(salicylidene)-2,2'-ethylenedianiline)Copper(II)) with a Schiff-base ligand ($H_2L$ = N,N'-bis (salicylaldimine)-1,2-ethylenediamine) containing two N,O-bidentate chelate groups. Though the copper sites of $Cu_4L_4$ are non-coupled, the complex exhibits a unsually high catecholase-like activity ($k_{cat}=935h^{-1}$) when the $Cu_4L_4$ solution is treated with 3,5-di-tert-butylcatechol (3,5-DTBC) at basic condition in the presence of air. Combined information obtained from UV-VIS and EPR measurements could lead the suggestion of the reaction pathway in which the substrate may bind to Cu(II) ions by anti-anti didentate bridging mode.

A Study on Complex Program of the Mixed-Use building - Focusing on Intermediary Space between Public and Private - (주상복합 실내공간의 복합 프로그램에 관한 연구 - 공(公), 사(私) 경계영역을 중심으로 -)

  • Yoon, Se-Eun;Kim, Jong-Jin
    • Proceedings of the Korean Institute of Interior Design Conference
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    • 2006.11a
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    • pp.58-61
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    • 2006
  • The mixed-use building is certainly one of the significant alternatives for urban dwelling based on the over-crowded urban condition as well as the ever-changing contemporary life patterns. It is clear that residential and other programs somehow are becoming more separated in most high quality mixed-use buildings in Seoul. Thus making the space between residential and other programs where diverse multi activities can be inserted is extremely important in terms of bridging the different urban programs. This research aims to briefly analyze the mixed-use programs in contemporary cities and case projects to see how they respond to unique characteristics of each projects by creating different mixed zones and spaces.

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Synthesis and Characterization of the Mixed-valence $[Fe^{II}Fe^{III}BPLNP(OAc)_2](BPh_4)_2$ Complex As a Model for the Reduced Form of the Purple Acid Phosphatase

  • Lee, Jae Seung;Jung, Dong J.;Lee, Ho Jin;Lee, Gang Bong;Heo, Nam Hoe;Jang, Ho G.
    • Bulletin of the Korean Chemical Society
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    • v.21 no.10
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    • pp.969-972
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    • 2000
  • [Fe II Fe III $BPLNP(OAc)_2](BPh_4)_2$ (1), a new model for the reduced form of the purple acid phosphatases, has been synthesized by using a dinucleating ligand, 2,6-bis[((2-pyridylmethyl)(6-methyl-2-pyridylmethyl)ami-no)methyl]-4-nitrophenol (HBPLNP) . Complex 1 has been studied by electronic spectral, NMR, EPR, SQUID, and electrochemical methods. Complex 1 exhibits two strong bands at 498 nm $(\varepsilon=$ 2.6 ${\times}10^3M-^1cm-^1)$ and 1363 nm $(\varepsilon=$ 5.7 ${\times}10^2M-^1cm-^1)$ in $CH_3CN.$ These are assigned to phenolate-to-FeIII and intervalence charge-transfer transitions, respectively. NMR spectrum of complex 1 exhibits sharp isotropically shifted resonances, which number is half of those expected for a valence-trapped species, indicating that electron transfer between FeⅡ and FeⅢ centers is faster than NMR time scale at room temperature. Complex 1 undergoes quasireversible one-electron redox processes. The $FeIII_2/FeIIFeIII$ and $FeIIFeIII/FeII_2$ redox couples are at 0.807 and 0.167 V ver-sus SCE, respectively. It has Kcomp = 5.9 ${\times}$10 1s(acetato) ligand combination sta-bilizes a mixed-valence FeIIFeIII complex in the air. Interestingly, complex 1 exhibits intense EPR signals at g = 8.56, 5.45, 4.30 corresponding to mononuclear high-spin FeⅢ species, which suggest a very weak magnetic coupling between the iron centers. Magnetic susceptibility study shows that there is a very weak antiferromag-netic coupling (J = $-0.78cm-^1$, H = $-2JS_1${\times}$S_2)$ between FeII and FeIII centers. Thus, we can suggest that complex 1 has a very weak antiferromagnetic coupling between the iron centers due to the electronic effect of the nitro group in the bridging phenolate ligand.