Publications by authors named "Chee Hun Kwak"

In the title mol-ecular salt, CHNS·I, prepared by the reaction of 1,3-di-phenyl-thio-urea and benzyl iodide, the C-S-C thio-ether bond angle is 101.66 (9)° and electrons are delocalized over the N= C-N skeleton. The dihedral angle between the aromatic rings attached to the N atoms is 40.

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The square-planar nickel(II) title complex, [Ni(CHFN)](ClO) or [Ni](ClO) ( = 3,10-bis-(4-fluoro-pheneth-yl)-1,3,5,8,10,12-hexa-aza-cyclo-tetra-deca-ne) was synthesized by a one-pot reaction of template condensation and its X-ray crystal structure was determined. The nickel(II) ion lies close by a twofold axis and the complex displays whole-mol-ecule disorder. Ligand , a hexa-aza-cyclo-tetra-decane ring having 4-fluoro-phenethyl side chains attached to uncoordinated nitro-gen atoms, adopts a III (, configuration.

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Complexes 1 and 2 were obtained by the reaction of [Cu(L1)](ClO4)2 (1) or [Cu(L2)](ClO4)2 (2) (L1 = 8-acetyl-1,3,6,8,10,13,15-heptaazatricyclo[13.1.1.

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Platinum complexes [Pt(bpy)Cl2](bpy: 2,2'-bipyridine) and [Pt(PT)Cl2](PT: 1,10-phenantroline) were reacted with 5,5"-(9,9-dioctyl-9H-fluorene-2,7-diyl)bis(2,2'-bipyrine), bpy-spiro-bpy, to afford mono and diplatinium complexes: [(bpy)Pt(bpy-spiro-bpy)][PF6]2, [(bpy)Pt(bpy-spiro-bpy)Pt(bpy)])[PF6]4, and [(PT)Pt(bpy-spiro-bpy)])][PF6]2, which were characterized by NMR, UV/VIS, mass spectrum, and PL spectroscopy. They showed very high internal quantum yields (0.35-0.

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In the title compound, C(17)H(25)N(3)O(3), there are intra-molecular hydrogen bonds between an amine H atom and the ep-oxy O atom, and between a dihydro-pyridine ring H atom and the ketone O atom. In the crystal, mol-ecules are linked into a zigzag chain running parallel to the c axis by hydrogen bonds between the hy-droxy group and the ketone O atom. There are also weak C-H⋯O and C-H⋯π inter-actions which link the mol-ecules into sheets lying in the bc plane.

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The diruthenium complexes, [(bpy)2Ru(II)-(bpy-DPDA)-Ru(II)(bpy)2][PF6]4 3, (bpy: 2,2'-bipyridiyl; bpy-DPDA: Bis(2,2'-dipyridylketenylidene)-N,N-1,4-phenylenediamine}, and [(bpy)2Ru(II)-(Dbpy-DPDA)-Ru(II)(bpy)2][PF6]4 4 {Dbpy-DPDA: Bis(2,2'-dipyridyl ketenylidene)-N,N-1,1'-(4,4'-diphenylene)diamine}, were prepared by the reaction of (bpy)2Ru(II)Cl2 with diimine-linked polypyridine bridges. These complexes were characterized by NMR, IR, UV/VIS, PL and cyclic voltammetry. In the 13C-NMR spectra of 3 and 4, the carbon peaks of the Schiff Bases (>C=N-) were shifted to lower fields, and emissions were observed at 689 and 693 nm with quantum yields of 0.

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In the title compound, C(22)H(28)O(3), the dihedral angle between the benzene rings is 3.47 (13)° and the five-membered furan ring is essentially planar with a largest deviation of 0.0052 (14) Å.

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The reaction of the [Pt(bpy-R)Cl2](bpy-R: R=H (2,2'-bipyridine); R=CH3 (4,4'-dimethyl-2,2'-biypridine (DM-bpy), 3,3'-5,5'-tertamethyl-2,2'-bipyridiyl (TM-bpy)) with 1,4-Bis(5'-2',2"-bipyridine)benzene (bpy-Ph-bpy) affords the following mono- and di-platinum complexes of [(bpy)Pt(bpy-Ph-bpy)][PF6]2 (1), [(bpy)Pt(bpy-Ph-bpy)Pt(bpy)])[PF6]4 (2), [(DM-bpy)Pt(bpy-Ph-bpy)])][PF6]2 (3), and [(TM-bpy)Pt(bpy-ph-bpy)[PF6]2 (4), respectively. These complexes were characterized by NMR, IR, UV/VIS, PL and cyclic voltammetry. The internal quantum yields of these platinum(II) complexes are very high (0.

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In the title compound, C(13)H(11)ClN(2)O(3), the nine-membered bicycle includes an oxime group having the C=N group in an E configuration. The isoxazole ring is almost planar [r.m.

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In the title compound, C(18)H(17)N(3), the dihedral angle between the dihydropyridine and phenyl rings is 72.57 (5)° and that between the dihydropyridine ring and malononitrile plane is 5.19 (20)°.

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The reaction of the iridium dimer [Ir(ppy)2(micro-Cl)]2 (ppy = 2-pyridiylphenyl) with bis(2,2'-bipyridin-5-yl) ethyne (bpy-C2-bpy), bis(2,2'-bipyridine)-butadiyne (bpy-C4-bpy), and bis(2,2'-bipyridin-5-yl-(Z)-hexa-3-ene-1,5-diyl) (bpy-C6H2-bpy) affords the following diiridium complexes: [ClO4]2 [(ppy)2Ir(bpy-C2-bpy)Ir(ppy)2] (1), [ClO4]2 [(ppy)2Ir(bpy-C4-bpy)Ir(ppy)2 (2), and [ClO4]2 [(ppy)2Ir(bpy-C6H6-bpy)Ir (ppy)2 (3), respectively. Herein, we describe the synthesis, characterization, and physical and electrochemical properties of the diiridium complexes in which the two iridium units are connected by a pi-conjugated nanowire bridge.

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The reaction of [Ir(ppy)2(micro-Cl)]2 (ppy = 2-pyridiylphenyl) with a substituted bpy ligand (5-bromo-2,2'-bipyridiyl, 5,5'-dibromo-2,2'-bipyridiyl, 5-ethynyl-2,2'-bipyridiyl) affords [Ir(ppy)2R-(bpy)-R'](CIO4) (R = H, R' = Br (1); R = R, R' = Br (2); R = H, R' = ethynyl (3)) in high yield. The structural, physical, and electrochemical properties of the iridium complexes 1, 2, and 3 were characterized by elemental analysis, NMR and optical spectroscopy, cyclic voltammetry, and X-ray structural analysis.

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Compound 2, [(eta5-C5Me5) Fe(dppe)]2(mu-C[triple bond]C-CH==CH-C[triple bond]C), was prepared by the reaction of compound 1, [eta5-C5Me5) Fe(dppe)]2+ (mu2-C==CH-CH=CH-HC=C).(PF6)2-, with KOBu(t). Compound 2 showed two quasi-reversible one-electron oxidations at -0.

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The X-ray structure, porous and magnetic property of a self-assembled network 1 is described in detail. The single crystal X-ray analysis provides 1 as a three-dimensional network, which contains two-dimensional permanent ring forming nanoscale one-dimensional channels. The inter-replacement of perchlorate and hexafluorophosphate anions in solid 1 proves its porous structure.

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Comparisons (25 degrees C) are made of substitution reactions, X replacing H(2)O, at the tetrahedral Ni of the heterometallic sulfido cuboidal cluster [Mo(3)NiS(4)(H(2)O)(10)](4+), I = 2.00 M (LiClO(4)). Stopped-flow formation rate constants (k(f)/M(-)(1) s(-)(1)) for six X reagents, including two water soluble air-stable phosphines, 1,3,5-triaza-7-phosphaadamantane PTA (119) and tris(3-sulfonatophenyl)phosphine TPPTS(3)(-) (58), and CO (0.

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