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ABSTRACT: An alternating stack (SG/GN) consisting of SnO2 -functionalized graphene oxide (SG) and amine-functionalized GO (GN) is prepared in solution. The thermally reduced SG/GN (r(SG/GN)) with decreased micro-mesopores and completely eliminated macropores, when compared to a composite without GN, results in a high reversible capacity and excellent capacity retention (872 mA h g(-1) after 200 cycles at 100 mA g(-1) ).
Advanced Materials 05/2013; · 13.88 Impact Factor
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ABSTRACT: Isostructural 3D metal-organic frameworks (MOFs) [Zn2(BTC)(NO3)S3] [where BTC = 1,3,5-benzenetricarboxylate; S = EtOH (1), DMF (2), DMA (3), or DEF (4)] of a 3-connected srs net topology have been prepared in the presence of serine as a template. The MOFs show different framework stabilities depending on the sizes of the ligated solvent molecules and undergo a crystal-to-crystal transformation at ambient conditions into a 1D chain structure either directly or via different types of intermediates depending on the ligated solvent molecules and the sample handling conditions. A single crystal of the MOF with the ligated DMF molecules, [Zn2(BTC)(NO3)(DMF)3] (2), is stable in MgII- and CoII-DMF solutions; however, it transforms into a single particle-like microcrystalline aggregate of Cu-HKUST-1 in a CuII-DMF solution.
Inorganic Chemistry 03/2013; · 4.60 Impact Factor
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ABSTRACT: Three novel soft porous coordination polymer (PCP) or metal?organic framework (MOF) compounds have been synthesized with a new rigid ligand N-(4-pyridyl)-1,4,5,8-naphathalenetetracarboxymonoimide (PNMI) by partial hydrolysis of N,N?-di-(4-pyridyl)-1,4,5,8-naphthalenete-tracarboxydiimide (DPNI) during solvothermal reactions with Zn(II), Cd(II), and Mn(II) salts, and they are [Zn(PNMI)]·2DMA (1·2DMA, 1a), [Cd(PNMI)]·0.5DMA·5H2O (2·0.5DMA·5H2O), and [Mn(PNMI)]·0.75DMF (3·0.75DMF). The structure of 1 is based on paddle-wheel secondary building unit (SBU) with a 3,6-connected rtl net topology, whereas 2 and 3 are isotypical but the M(O2C?C)2 fragments aggregate in one-dimension and the overall connectivity is the same rtl net topology. All these three MOFs have one-dimensional rhombic channels filled with guest molecules. The guest molecules in 1a can be exchanged with EtOH in a single-crystal to single-crystal (SCSC) manner to 1·1.25EtOH·0.375H2O (1b). Further, the guest molecules in 1b can be re
Inorganic Chemistry 03/2013; · 4.60 Impact Factor
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Vaishali Vajpayee,
Sunmi Lee,
Seol-Hee Kim,
Se Chan Kang,
Timothy R Cook,
Hyunuk Kim,
Dong Wook Kim,
Shashi Verma, Myoung Soo Lah,
In Su Kim,
Ming Wang,
Peter J Stang,
Ki-Whan Chi
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ABSTRACT: Sixteen arene-Ru based molecular-rectangles were self-assembled in high yields by the equimolar mixing of arene-Ru acceptors () with various azopyridyl ligands (1,2-di(pyridyl-4yl)diazene (), 1,2-bis(pyridin-4-ylmethylene)hydrazine (), 1,2-bis(1-(pyridin-4-yl)ethylidene)hydrazine (), 1,2-bis(pyridin-4-ylmethylene)hydrazine ()) in nitromethane-methanol solutions. These new molecular-rectangles were fully characterized by a host of analytical techniques including elemental analysis, (1)H and (13)C NMR and HR-ESI-MS. The solid-state structures of two molecular-rectangles ( and ) were determined by single crystal X-ray diffraction data. UV-visible and fluorescence studies were also carried out for the entire suite of rectangles. As with recent studies of similar arene-Ru complexes, the anti-proliferative activities of these complexes were evaluated against SK-hep-1 (liver cancer) and A-549 (lung cancer) human cancer lines. Additionally, the cellular pharmacology and intracellular localizations in AGS (gastric cancer) human cancer cells were determined for selected complexes (, and ) by apoptosis and fluorescence microscopy studies. These studies confirm that arene-Ru molecular-rectangles inhibit cell cycle progression to the G0 phase, in contrast to that of cisplatin which arrests cell growth in the G2 phase.
Dalton Transactions 10/2012; · 3.84 Impact Factor
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ABSTRACT: A series of synthetic molecules bearing the same hydrogen bonding mode observed in StClC were prepared and their transport ability of chloride ion across a lipid membrane was systematically optimized.
Chemical Communications 09/2012; 48(83):10346-8. · 6.17 Impact Factor
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Vaishali Vajpayee,
Young Ho Song,
Yoon Jung Yang,
Se Chan Kang,
Timothy R Cook,
Dong Wook Kim, Myoung Soo Lah,
In Su Kim,
Ming Wang,
Peter J Stang,
Ki-Whan Chi
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ABSTRACT: A series of supramolecular rectangles, including two mixed-metal Ru/Pt complexes, have been formed by the coordination-driven self-assembly of a range of arene-Ru "molecular clip" acceptors (1a-1d) with rigid dipyridyl-based ligands (2a-2d) over the course of 10 hours in solution. The isolated products were characterized by multinuclear NMR ((1)H and (13)C or (31)P), HR-ESI-MS and an X-ray diffraction study to support the ascribed two-component rectangular structures. The rectangles were further characterized by UV-Vis and fluorescence studies. The redox behaviors of rectangles 3ca and 3da were also determined using cyclic voltammetry. Additionally, the antitumor activities of the suite of rectangles were determined against various human cancer cell lines and significant activity was shown by complexes 3ca, 3da, 3cb, 3cc and 3cd, with IC(50) values as low as 2.65 μM.
Organometallics 12/2011; 30(23):6482-6489. · 3.96 Impact Factor
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ABSTRACT: Solvothermal reactions of manganese(II) chloride tetrahydrate with a bis-tetrazole ligand, 2,6-di(1H-tetrazol-5-yl)naphthalene (H(2)NDT), in N,N'-dimethylformamide (DMF)/MeOH mixed solvent at two slightly different temperatures, 75 and 100 °C, led to two different metal-organic frameworks (MOFs), [Mn(II)(3)O(HNDT)(2)(NDT)(DMF)(3)] (1) and [Mn(II)(5)O(2)(HNDT)(2)(NDT)(2)(DMF)(8)] (2), with different net topologies. Single-crystal X-ray diffraction studies reveal that 1 is constructed from an unprecedented trinuclear building block, [Mn(II)(3)O(CN(4))(6)], as a 6-connected trigonal prismatic secondary building unit (SBU) of topological D(3h) site symmetry, and that the ligand in the HNDT(-1)/NDT(2-) deprotonation states is a linker, where two tetrazole (CN(4)) groups of the ligand are connected via a rigid naphthyl group. The tetrazole groups in 1 adopt a 1,2-μ-bridging mode with the manganese(II) ions to form a μ(3)-oxo trinuclear SBU. The trigonalprismatic SBU in 1 is connected to six neighboring SBUs to form a three-dimensional MOF of acs net topology. 2 is constructed from an unprecedented pentanuclear building block, [Mn(II)(5)O(2)(CN(4))(8)], as an 8-connected tetragonal prismatic SBU of topological D(4h) site symmetry. The tetrazole groups in 2 adopt monodentate, 1,2-μ- and 2,3-μ-bridging bidentate and 1,2,3-μ-bridging tridentate binding modes with the manganese(II) centers to form a bis-μ(3)-oxo pentanuclear SBU of local C(2) site symmetry. The tetragonal prismatic SBU in 2 is connected to eight neighboring SBUs to form a 3-D MOF of bcu net topology.
Inorganic Chemistry 11/2011; 50(23):12133-40. · 4.60 Impact Factor
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ABSTRACT: Chiral indolocarbazole dimers fold into a helical conformation by virtue of intramolecular hydrogen bonds, as demonstrated by (1)H NMR and CD spectra and optical rotations. In particular, the optical properties of the dimers were found to be extremely sensitive to the nature of the solvent, depending on whether they are folded or not. The helical sense of the dimers can be reversibly switched by binding sulfate ion, which gives rise to complete inversion of the CD spectra. The binding mode and absolute stereochemistry of the sulfate complexes was unequivocally determined by single-crystal X-ray structures, which are all consistent with the CD and (1)H NMR spectra in solution.
Journal of the American Chemical Society 08/2011; 133(35):13938-41. · 9.91 Impact Factor
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Young Joo Song,
Sun Hwa Lee,
Hyun Min Park,
Soo Hyun Kim,
Hyo Geun Goo,
Geun Hee Eom,
Ju Hoon Lee, Myoung Soo Lah,
Youngmee Kim,
Sung-Jin Kim,
Ju Eun Lee,
Hong-In Lee,
Cheal Kim
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ABSTRACT: Two new mononuclear nonheme manganese(III) complexes of tetradentate ligands containing two deprotonated amide moieties, [Mn(bpc)Cl(H(2)O)] (1) and [Mn(Me(2)bpb)Cl(H(2)O)]⋅CH(3)OH (2), were prepared and characterized. Complex 2 has also been characterized by X-ray crystallography. Magnetic measurements revealed that the complexes are high spin (S = 5/2) Mn(III) species with typical magnetic moments of 4.76 and 4.95 μ(B), respectively. These nonheme Mn(III) complexes efficiently catalyzed olefin epoxidation and alcohol oxidation upon treatment with MCPBA under mild experimental conditions. Olefin epoxidation by these catalysts is proposed to involve the multiple active oxidants Mn(V)=O, Mn(IV)=O, and Mn(III)-OO(O)CR. Evidence for this approach was derived from reactivity and Hammett studies, KIE (k(H)/k(D)) values, H(2)(18)O-exchange experiments, and the use of peroxyphenylacetic acid as a mechanistic probe. In addition, it has been proposed that the participation of Mn(V)=O, Mn(IV)=O, and Mn(III)-OOR could be controlled by changing the substrate concentration, and that partitioning between heterolysis and homolysis of the O-O bond of a Mn-acylperoxo intermediate (Mn-OOC(O)R) might be significantly affected by the nature of solvent, and that the O-O bond of the Mn-OOC(O)R might proceed predominantly by heterolytic cleavage in protic solvent. Therefore, a discrete Mn(V)=O intermediate appeared to be the dominant reactive species in protic solvents. Furthermore, we have observed close similarities between these nonheme Mn(III) complex systems and Mn(saloph) catalysts previously reported, suggesting that this simultaneous operation of the three active oxidants might prevail in all the manganese-catalyzed olefin epoxidations, including Mn(salen), Mn(nonheme), and even Mn(porphyrin) complexes. This mechanism provides the greatest congruity with related oxidation reactions by using certain Mn complexes as catalysts.
Chemistry 06/2011; 17(26):7336-44. · 5.93 Impact Factor
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ABSTRACT: The self-assembly of a polyprotic pentadentate ligand, N-cyclopentanoylaminobenzoylhydrazide (H(4)L(4)), and an In(III) nitrate hydrate in methanol led to a strained hexanuclear indium metal-organic macrocycle (In-MOM), [In(III)(6)(H(2)L(4))(6)(NO(3))(x)(solvent)(6-x)](NO(3))(6-x) (where, the solvent is either methanol or a water molecule and x is the number of the nitrate anions ligated). The ligand in the doubly deprotonated state serves as an unsymmetric linear ditopic donor and the alternating indium ions in two different chelation modes serve as two different bent ditopic metal acceptors, which led to a D(3)-symmetric hexanuclear In-MOM. Although the hexanuclear In-MOM is enthalpically unfavorable because of the ring strain, the combination of the soft coordination characteristic of the indium ion and the slight ligand deformation from the conjugated planar conformation allows the formation of the entropically favored hexanuclear In-MOM rather than the enthalpically favored octanuclear In-MOM. While the hexanuclear In-MOM is stable in acetonitrile, it partially dissociates into its components in dimethylsulfoxide, and then slowly reaches a new equilibrium state with several different indium species yet to be identified in addition to the free ligand.
Dalton Transactions 06/2011; 40(21):5720-7. · 3.84 Impact Factor
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ABSTRACT: Two isostructural metal-organic frameworks (MOFs) having micropores of the same "static aperture size" but different "effective aperture size" have been prepared using 5-(pyridin-3-ylethynyl)isophthalic acid as a ligand having two different types of functional units, an isophthalate (iph) unit and a pyridyl unit, simultaneously in a single ligand. The combination of iph unit and Cu (or Zn) ion led to two-dimensional layers of Kagomé (kgm) net topology, the layers being further pillared by the internal auxiliary pyridyl unit to form a three-dimensional microporous framework having two different types of cage-like pores, cage A and cage B, with different aperture sizes and shapes. (1) The MOFs can distinguish the adsorbates (N(2)/Ar) not based on the widely used kinetic diameters of the adsorbates but based on the minimum diameters of the adsorbates, which are more shape dependent. While cage A with a sufficiently large aperture size compared with the size of the adsorbates does not show any size selectivity, cage B with an approximate size match between the adsorbates and the pore apertures shows shape selectivity for the adsorbates. The smaller but spherically shaped Ar atom is not allowed into the pore with the oval-shaped aperture; however, the larger linear N(2) molecule is allowed into the pore with the oval-shaped aperture. (2) Even though the two isostructural MOFs have the same static aperture size of cage B, they show different size selectivity for the adsorbates based on the effective aperture size, which reflects the different extents of the framework flexibility.
Inorganic Chemistry 06/2011; 50(11):5044-53. · 4.60 Impact Factor
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ABSTRACT: A metal-organic macrocycle (MOM), [(Cu(2))(3)L(6)(DMF)(2)(H(2)O)(4)], was prepared using a long and "pseudo-rigid" dicarboxylic acid, 1,4-bis(3-carboxylphenylethynyl)benzene (H(2)L), with some rotational flexibility, where the MOM has a double-walled triangular geometry with three Cu paddle-wheel secondary building units (SBUs) doubly connected by the ligands in a cis-conformation.
Dalton Transactions 07/2010; 39(27):6178-80. · 3.84 Impact Factor
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ABSTRACT: A microporous metal−organic framework (MOF), [Zn2L2(dabco)], was prepared using a long and rigid dicarboxylic acid, 1,4-bis(3-carboxylphenylethynyl)benzene (H2L), with some rotational flexibility, and an auxiliary bridging diamine linker, 1,4-diazabicyclo[2.2.2]octane (dabco). The MOF, based on a Zn paddle-wheel secondary building unit, has [2 + 2] parallel and inclined interpenetrating 2D sheets interconnected by dabco to form a 3D network with 1D helical channels.
05/2010;
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ABSTRACT: A general strategy was developed for edge-directed self-assembly of tetragonal metal-organic polyhedra (MOPs) having a C(4) symmetry Cu(II)(2)(COO)(4) paddle-wheel as a secondary building unit, using C(2) symmetric dicarboxylic ligands as pincer-type primary building units.
Chemical Communications 03/2010; 46(12):2049-51. · 6.17 Impact Factor
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ABSTRACT: Hydrogen bonding to anions drives the helical folding of an indolocarbazole oligomer, thus resulting in an internal cavity with six NHs and two OHs for binding sulfate with high selectivity.
Chemical Communications 02/2010; 46(5):764-6. · 6.17 Impact Factor
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ABSTRACT: New complex [Mn(II)H1.5L]2[Mn(II)H3L]2(ClO4)5·3H2O (1), where H3L is tris{2-(4-imidazolyl)methyliminoethyl}amine (imtren), has been prepared by reacting manganese(II) perchlorate hexahydrate with the imtren ligand in
methanol. X-ray crystallographic study revealed that the imtren ligand hexadentately binds to Mn(II) ion through the three Schiff-base imine N atoms and three imidazole N atoms with a distorted octahedral geometry, and the apical tertiary amine N atom of the ligand pseudo-coordinates to Mn(II), forming overall a pseudo-seven coordination environment. The hydrogen-bonds between imidazole and imidazolate of [Mn(II)H1.5L]0.5+ complex ions are extended to build a 2D puckered network with trigonal voids. [Mn(II)H3L]2+ complex ions constitutes another extended 2D puckered layer without hydrogen bonds. Two layers are wedged each other to constitute overall stack of the crystal. Peroxidase activity of complex 1 was examined by observing the oxidation of 2,2'-azinobis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) with hydrogen peroxide in the presence of complex 1. Generation of ABTS+• was observed by UV-vis and EPR spectroscopies, indicating that the complex 1, a fully-coordinated mononuclear Mn(II) complex with nitrogen-only ligand, has a heme-independent peroxidase activity.
Bull. Korean Chem. Soc. 01/2010; 31:3173-3179.
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ABSTRACT: A twofold interpenetrating polyhedron-based metal-organic framework with high hydrothermal stability was prepared using a rigid and bent C(2)-symmetric ligand containing two 3,5-benzenedicarboxylate units, which have large surface area and high uptake capacities for various gas molecules.
Inorganic Chemistry 11/2009; 48(24):11507-9. · 4.60 Impact Factor
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ABSTRACT: Two metal-organic frameworks (MOFs) based on metal-organic cuboctahedra were prepared using a rigid C3 symmetric ligand, where Zn polyhedron-based MOF (PMOF-2(Zn)) did not show any significant gas sorption behavior, whereas the isostructural Cu polyhedron-based MOF (PMOF-2(Cu)) showed a large surface area of approximately 4180 m2 g(-1), high hydrothermal stability, and very promising H2 sorption properties.
Chemical Communications 10/2009; · 6.17 Impact Factor
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ABSTRACT: Metal-organic macrocycles (MOMs), metal-organic polyhedra (MOPs) and metal-organic frameworks (MOFs) are metal-organic systems (MOSs) developed from appropriately designed ligands and selected metal ions. Metalladiazamacrocycles, a class of MOMs, are finite 2D MOSs formed from tricationic hexacoordinate metal ions and ditopic bridging ligands, N-acylsalicylhydrazide, containing diaza residues, where the size and shape of the systems have been modulated by controlling the steric repulsions between the ligands. The 2D MOM systems could be expanded to 3D MOP systems by self-assembling C(3) symmetric components and C(4) symmetric components to octahedral MOPs. By substituting some replaceable solvent sites of MOMs or MOPs, MOFs based on MOMs or MOPs as SBBs have been constructed, where the properties of the SBBs have been directly transferred to the MOF systems.
Chemical Communications 07/2009; · 6.17 Impact Factor
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ABSTRACT: A new building block containing an imidazolium salt was synthesized and used for the construction of supramolecular networks with metal ions. We discovered the concomitant formation of the N-heterocyclic carbene-copper complex (CN = 2) in the self-assembly of imidazolium dicarboxylates and copper nitrates in N,N-dimethylformamide under heating. The proton in the 2 position of the imidazolium salt was abstracted, and Cu(II) was reduced to Cu(I) during the self-assembly process.
Inorganic Chemistry 07/2009; 48(14):6353-5. · 4.60 Impact Factor
