Biomedical subjects

Kwang-Hwa Lii

Publications and source records attributed to Kwang-Hwa Lii.

At least 19 recordsLinked to original sources

PubMed2006

Hydrothermal synthesis of a three-dimensional organic-inorganic hybrid network formed by poly(oxomolybdophosphate) anions and nickel coordination cations.

A novel organic-inorganic hybrid nickel molybdenum(V) phosphate has been synthesized hydrothermally and characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and magnetic susceptibility. The structure consists of poly(oxomolybdophosphate) anions linked by both Ni(II) cations and 4,4-bipyridine bridging ligands to form a three-dimensional open-framework structure with large cavities where the uncoordinated 4,4'-bipyridinium cations and lattice water molecules are located. This is the first example of an extended framework solid containing poly(oxomolybdophosphate) anions interconnected by both transition-metal complexes and organic moieties. Crystal data: (4,4'-H2bpy)[Ni(4,4'-bpy)(H2O)2Ni(0.5)Mo6(OH)3O12(HPO4)4].2H2O, orthorhombic, space group Pccn (No. 56), a = 27.745(2) A, b = 16.158(1) A, c = 22.819(2) A, V =10230.3(1) A(3), and Z = 8.

Journal Article↗

PubMed2006

Ionothermal synthesis of metal oxalatophosphonates with a three-dimensional framework structure: Na2M3(C2O4)3(CH3PO3H)2 (M = FeII and MnII).

Two isostructural transition-metal oxalatophosphonates, Na2M3(C2O4)3(CH3PO3H)2 (M = Fe(II) and Mn(II)), have been synthesized by using a low-melting-point eutectic mixture of choline chloride and malonic acid as a solvent and characterized by single-crystal X-ray diffraction and 57Fe Mössbauer spectroscopy. The 3D framework structure consists of a corner-sharing octahedral trimer that is linked with other trimers through two distinct oxalate ligands with unusual linkage types, phosphonate tetrahedra, and H bonds to form infinite channels along the [101] direction where the Na+ cations are located. They are the first examples for the use of an ionic liquid as a solvent in the synthesis of metal oxalatophosphonates. Crystal data for the Fe compound follow: monoclinic, P2(1)/n (No. 14), a = 5.8063(1) A, b = 10.3867(3) A, c = 14.8094(4) A, beta = 96.926(1) degrees , and Z = 2. Crystal data for the Mn compound are the same as those for the Fe compound except a = 5.8734(9) A, b = 10.557(2) A, c = 14.863(2) A, and beta = 96.691(2) degrees .

Journal Article↗

PubMed2006

Ionic liquid of choline chloride/malonic acid as a solvent in the synthesis of open-framework iron oxalatophosphates.

Two new iron(III) oxalatophosphates, Cs2Fe(C2O4)(0.5)(HPO4)2 (1) and CsFe(C2O4)(0.5)(H2PO4)(HPO4) (2), have been synthesized by using a low melting point eutectic mixture of choline chloride and malonic acid as a solvent and characterized by single-crystal X-ray diffraction and magnetic susceptibility. Crystal data are as follows: compound 1, monoclinic, P2(1)/c (No. 14), a = 8.5085(4) A, b = 12.7251(6) A, c = 9.8961(4) A, beta = 107.117(1) degrees , V = 1024.01(8) A(3), Z = 4, and R(1) = 0.0264; compound 2, monoclinic, P2(1)/n (No. 14), a = 8.0038(3) A, b = 10.2923(3) A, c = 11.4755(4) A, beta = 100.507(1) degrees , V = 929.47(5) A(3), Z = 4, and R(1) = 0.0311. The structure of 1 comprises FeO6 octahedra connected by HPO4(2-) tetrahedra and bisbidentate oxalate anions to form a 3D framework containing intersecting 12-ring channels, with the charge-compensating Cs+ cations being located at the intersections of these channels. The structure of 2 consists of 2D layers of octahedral FeO6, tetrahedral H2PO4- and HPO4(2-) moieties, and bisbidentate oxalate ligands with the Cs+ cations between the layers. They are the first examples for the use of ionic liquid as a solvent in the synthesis of metal oxalatophosphates.

Journal Article↗

PubMed2006

Rb6(InCo)2(Si9O26): a mixed-metal silicate containing 20-membered-ring silicate single layers with a very low Si:O ratio.

A new cobalt-indium silicate, Rb6(InCo)2(Si9O26), has been synthesized via a high-temperature, high-pressure hydrothermal method and characterized by single-crystal X-ray diffraction. It crystallizes in the noncentrosymmetric orthorhombic space group Aba2 (No. 41) with a = 20.779(1) A, b = 12.0944(6) A, c = 10.7761(5) A, V =2708.1(2) A(3), and Z = 4. The structure consists of 20-membered-ring silicate single layers of corner-sharing SiO4 tetrahedra interconnected by dimers of edge-sharing CoO4 tetrahedra and InO6 octahedra into a 3D framework. The Si:O ratio for the title compound is the lowest among the known single-layer silicates. Magnetic susceptibility confirms the divalent state of the cobalt ion. The powder sample has a second-harmonic-generation signal, confirming the absence of a center of symmetry in the structure.

Journal Article↗

PubMed2006

UF3(H2O)(C2O4)0.5: a fluorooxalate of tetravalent uranium with a three-dimensional framework structure.

A new uranium(IV) fluorooxalate, UF3(H2O)(C2O4)0.5, has been synthesized by a hydrothermal method and structurally characterized by single-crystal X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. The structure consists of two-dimensional layers of corner- and edge-sharing tricapped trigonal prisms with the composition UF(4/2)F(2/2)O3 linked by bisbidentate oxalate ligands to form a three-dimensional framework. Magnetic susceptibilities were measured to confirm the tetravalent state of uranium. Crystal data: monoclinic, space group C2/c, a = 17.246(3) Angstroms, b = 6.088(1) Angstroms, c = 8.589(2) Angstroms, beta = 95.43(3) degrees, and Z = 8.

Journal Article↗

PubMed2005

Synthesis, crystal structure, and solid-state NMR spectroscopy of a salt-inclusion stannosilicate: [Na3F][SnSi3O9].

A salt-inclusion stannosilicate, [Na3F][SnSi3O9], has been synthesized using a flux-growth method and characterized by single-crystal X-ray diffraction. The structure consists of six-membered silicate rings linked via corner sharing by SnIVO6 octahedra to form a 3-D framework that delimits two types of channels. The F atoms and Na atoms are located in the structural channels and form a dimer with the anti-Al2Cl6(g) structure. This stannosilicate adopts a new structure and is the first metal silicate that contains both Na+ and F- ions in the channels. The 19F and 29Si MAS NMR and 23Na MQMAS NMR spectra are consistent with the crystallographic results.

Journal Article↗

PubMed2005

K(UO)Si2O6: a pentavalent-uranium silicate.

We report the first example of pentavalent-uranium silicate synthesized by a high-temperature, high-pressure hydrothermal method. The 3-D framework consists of four-membered single rings of corner-sharing SiO4 tetrahedra and 1-D UO4/1O2/2 chains. Magnetic susceptibility and XPS were measured to identify the valence state of uranium.

Journal Article↗

PubMed2005

Hydrothermal synthesis and characterization of [(UO2)2F8(H2O)2Zn2(4,4'-bpy)2].(4,4'-bpy), a mixed-metal uranyl aquofluoride with a pillared layer structure.

A mixed-metal uranyl aquofluoride, [(UO2)2F8(H2O)2Zn2(4,4'-bpy)2].(4,4'-bpy), has been synthesized under hydrothermal conditions and has been structurally characterized by single-crystal X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, emission spectroscopy, and solid-state NMR spectroscopy. It is one of the few uranium fluoride-organic framework solids in which an organic molecule is directly incorporated into the extended structure of the metal fluoride and is the first example of mixed-metal uranium oxyfluoride incorporating an organic ligand. The structure consists of neutral layers of edge- and corner-sharing uranium-centered pentagonal bipyramids and zinc-centered octahedra, which are linked through 4,4'-bpy ligands into a 3-D framework. The 1H MAS NMR spectrum is in support of the conclusion that the occluded 4,4'-bpy molecules in the structural channels are not protonated. Crystal data: monoclinic, space group P2(1)/c, a = 9.4630(5) A, b = 22.384(1) A, c = 16.7534(8) A, beta = 91.899(2) degrees , V = 3546.7(4) A(3) and Z = 4.

Journal Article↗

PubMed2005

High-temperature, high-pressure hydrothermal synthesis, crystal structure, and solid-state NMR spectroscopy of Cs2(UO2)(Si2O6) and variable-temperature powder X-ray diffraction study of the hydrate phase Cs2(UO2)(Si2O6) x 0.5H2O.

A new uranium(VI) silicate, Cs2(UO2)(Si2O6), has been synthesized by a high-temperature, high-pressure hydrothermal method and characterized by single-crystal X-ray diffraction and solid-state NMR spectroscopy. It crystallizes in the orthorhombic space group Ibca (No. 73) with a = 15.137(1) A, b = 15.295(1) A, c = 16.401(1) A, and Z = 16. Its structure consists of corrugated achter single chains of silicate tetrahedra extending along the c axis linked together via corner-sharing by UO6 tetragonal bipyramids to form a 3-D framework which delimits 8- and 6-ring channels. The Cs+ cations are located in the channels or at sites between channels. The 29Si and 133Cs MAS NMR spectra are consistent with the crystal structure as determined from X-ray diffraction, and the resonances in the spectra are assigned. Variable-temperature in situ powder X-ray diffraction study of the hydrate Cs2(UO2)(Si2O6) x 0.5H2O indicates that the framework structure is stable up to 800 degrees C and transforms to the structure of the title compound at 900 degrees C. A comparison of related uranyl silicate structures is made.

Journal Article↗

PubMed2005

Rb3In(H2O)Si5O13: a novel indium silicate with a CdSO4-topological-type structure.

A novel indium silicate, Rb3In(H2O)Si5O13, has been synthesized using a high-temperature, high-pressure hydrothermal method and characterized by single-crystal X-ray diffraction. The structure consists of five-membered rings of corner-sharing SiO4 tetrahedra connected via corner sharing to four adjacent five-membered rings to form a 3D silicate framework that belongs to the CdSO4 topological type. The InO6 octahedron shares five of its corners with five different SiO4 tetrahedra to form a 3D frame-work that delimits two types of channels to accommodate the rubidium cations. The sixth corner of InO6 is coordinated H2O. The structure is related to that of the titanium silicate ETS-10, and these are the only two metal silicates that have the CdSO4-topological-type structure. In addition, the crystal of Rb3In(H2O)Si5O13 shows an intense second harmonic generation signal. Crystal data: H2Rb3InSi5O14, monoclinic, space group Cc (No. 9), a = 9.0697(5) A, b = 11.5456(6) A, c = 13.9266(8) A, beta = 102.300(1) degrees, V = 1424.8(1) A3, and Z = 4.

Journal Article↗

PubMed2005

K5(UO2)2[Si4O12(OH)]: a uranyl silicate containing chains of four silicate tetrahedra linked by SiO...HOSi hydrogen bonds.

A new uranium(VI) silicate, K5(UO2)2[Si4O12(OH)], has been synthesized by a high-temperature, high-pressure hydrothermal method. It crystallizes in the orthorhombic space group Pbcm (No. 57) with a = 13.1274(7) A, b = 12.2635(7) A, c = 22.233(1) A, and Z= 8. Its structure consists of unbranched chains of four silicate tetrahedra extending along the b axis linked together via corner-sharing by UO6 tetragonal bipyramids to form a 3-D framework, which delimits intersecting channels along the c and b axes to accommodate K+ cations. A hydrogen atom is bonded to a terminal oxygen of a terminal silicate in the oligosilicate anion. Adjacent chains are linked along the b axis by hydrogen bonds. The sample shows a resonance at 14.7 ppm the 1H MAS NMR spectrum, which is assigned to the SiO...HOSi hydrogen bond. A comparison of uranyl silicate structures is made.

Journal Article↗

PubMed2005

First example of a 2:1 cocrystal of mixed Cu(I)/Cu(II) complexes and a novel ferromagnetic bis(mu-hydroxo)dicopper(II) complex with a bis(pyrazol-1-yl)methane bidentate ligand.

A unique 2:1 cocrystal of mixed Cu(I)/Cu(II) complexes [Cu(I)(H2CPz2)(MeCN)2](ClO4) (1) and [Cu(II)(H2CPz2)2(ClO4)2] (4), a novel ferromagnetic ClO(4-)-bridged bis(mu-hydroxo)dicopper(II) complex, [Cu2(H2CPz2)2(OH)2(ClO4)](ClO4)(CH3CN)(0.5) (5), and a bischelated copper(I) complex, [Cu(H2CPz2)2](ClO4) (2), prepared from a one-pot reaction of [Cu(MeCN)4](ClO4) and H2CPz2, are described. The structures of these complexes have been determined by X-ray crystallographic methods. The Cu(I)-N(acetonitrile) bond distances in complex 1 are nonequivalent (1.907(8) and 2.034(9) A), leading to the dissociation of one MeCN to form a Y-shaped complex, [Cu(I)(H2CPz2)(MeCN)](ClO4) (3), which is oxidized readily in air to form complex 5 with a butterfly Cu2O2 core.

Journal Article↗

PubMed2004

[N(CH2CH2NH3)3][U3O2F13].2H2O: a novel organically templated mixed-valent uranium oxyfluoride with a hybrid network structure.

The synthesis and characterization of a novel mixed-valent uranium oxyfluoride is described; the inorganic network consists of 2-D [U(2)F(10)](2)(-) sheets constructed from corner- and edge-sharing U(IV)F(9) tricapped trigonal prisms and 1-D [UO(2)F(3)](-) chains constructed from edge-sharing U(VI)O(2)F(5) pentagonal bipyramids with the organic cations and water molecules between the sheets. This is the first example with a hybrid network structure in the system of uranium fluoride or oxyfluoride. The variable-temperature magnetic susceptibility confirms the oxidation state of the uranium ions. Crystal data follow: C(6)H(25)N(4)O(4)F(13)U(3), monoclinic, space group P2(1) (No. 4); a = 8.6876(4) A, b = 7.3158(4) A, c = 16.3376(8) A, beta = 93.7285(9) degrees , V = 1036.2(2) A(3), and Z = 2.

Journal Article↗

PubMed2004

Synthesis and characterization of the first organically templated metal oxalatophosphonate: (C3H12N2)0.5[Ga3(C2O4)(CH3PO3)4].0.5H2O.

The first organically templated gallium oxalatophosphonate has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. The structure consists of GaO(6) octahedra and GaO(4) tetrahedra connected by methylphosphonate and bis-bidentate oxalate anions to form anionic sheets in the ab plane with the charge-compensating propylenediammonium cations and water molecules between the sheets. The methyl groups of the phosphonate ligands extend from both sides of the layers into the interlamellar region. Crystal data: monoclinic, space group P2(1)/n (No. 14), a = 8.8514(4) A, b = 16.3030(7) A, c = 15.0816(7) A, beta = 97.539(1) degrees, and Z = 4.

Journal Article↗

PubMed2004

Metamagnetism in cobalt phosphates with pillared layer structures: [Co3(pyz)(HPO4)2F2] and [Co3(4,4'-bpy)(HPO4)2F2].xH2O.

Two new cobalt phosphates, [Co(3)(pyz)(HPO(4))(2)F(2)] (1) and [Co(3)(4,4'-bpy)(HPO(4))(2)F(2)].xH(2)O (x approximately 0.7) (2), have been synthesized by hydrothermal methods in the presence of aromatic amines, and characterized by single-crystal X-ray diffraction and magnetic susceptibility. Their structures consist of neutral sheets of fluorinated cobalt phosphate which are pillared through pyrazine and 4,4'-bipyridine molecules to form 3D frameworks. The structures are related to that of the mineral lazulite. Both compounds show long-range antiferromagnetic ordering below 15 K and metamagnetic behaviors. Compound 1 reveals a two-step magnetic phase transition. Crystal data for 1: monoclinic, space group C2/c (No. 15), a = 21.809(4) A, b = 7.370(1) A, c = 7.395(1) A, beta = 103.753(3) degrees, and Z = 4. Crystal data for 2 are the same as those for 1 except a = 29.940(2) A, b = 7.4421(5) A, c = 7.4170(5) A, and beta = 93.444(1) degrees.

Journal Article↗

PubMed2004

Cs2Pd3(P2O7)2 and Cs2Pd3(As2O7)2: a 3D palladium phosphate with a tunnel structure and a 2D palladium arsenate containing strings of palladium atoms.

Cs(2)Pd(3)(P(2)O(7))(2) (1) and Cs(2)Pd(3)(As(2)O(7))(2) (2) have been synthesized by molten flux reactions and characterized by single-crystal X-ray diffraction. The structure of 1 consists of discrete Pd(II)O(4) squares which are linked by P(2)O(7) groups via corner-sharing to generate a 3D framework containing 12-ring channels in which Cs(+) cations are located. Compound 2 adopts a 2D layer structure with the interlayer space filled with Cs(+) cations. Within a layer there are PdO(4) squares and As(2)O(7) groups fused together via corner-sharing. Adjacent layers are stacked such that strings of Pd atoms are formed. The PdO(4) squares show eclipsed and staggered stacks with alternate short and long Pd...Pd distances. The two compounds adopt considerably different structures although they have the same general formula: Cs(2)Pd(3)(X(2)O(7))(2). Compound 2 is the first palladium arsenate reported. Crystal data for 1: orthorhombic, space group Cmc2(1) (No. 36), a = 7.6061(4) A, b = 14.2820(7) A, c = 14.1840(7) A, and Z = 4. Crystal data for 2: tetragonal, space group P4/n (No. 85), a = 16.251(1) A, c = 5.9681(5) A, and Z = 4.

Journal Article↗

PubMed2003

Novel transition metal oxalatophosphates with a two-dimensional honeycomb structure: (H3TREN)[M2(HPO4)(C2O4)2.5] x 3H2O (M = Mn(II) and Fe(II), TREN = tris(2-aminoethyl)amine).

Two new layered transition metal oxalatophosphates, (H(3)TREN)[M(2)(HPO(4))(C(2)O(4))(2.5)].3H(2)O (M = Mn(II) and Fe(II)), have been synthesized by hydrothermal methods in the presence of a structure-directing organic amine, tris(2-aminoethyl)amine, and characterized by single-crystal X-ray diffraction and magnetic susceptibility. They are the first metal oxalatophosphates which adopt a two-dimensional honeycomb structure with the organic cations and water molecules intercalated in between. Within a layer, there are 12-membered pores made from 6 Mn, 1 phosphate, and 5 oxalate units. Measurements of field dependence of magnetization and variable-temperature susceptibilities under different fields were performed on a polycrystalline sample of the manganese compound. The results indicate a phase transition from a paramagnetic to an antiferromagnetic coupled state at about 12 K. Crystal data for the manganese compound follow: triclinic, space group Ponemacr; (No. 2), a = 8.8385(6) A, b = 9.0586(6) A, c = 16.020(1) A, alpha = 77.616(1) degrees, beta = 83.359(1) degrees, gamma = 68.251(1) degrees, and Z = 2. Crystal data for the iron compound are the same as those for the manganese compound except a = 8.7776(9) A, b = 8.9257(9) A, c = 15.884(2) A, alpha = 78.630(2) degrees, beta = 84.018(2) degrees, and gamma = 67.372(2) degrees.

Journal Article↗

PubMed2003

Hydrothermal synthesis, crystal structure, and solid-state NMR spectroscopy of a new indium silicate: K2In(OH)(Si4O10).

A new indium(III) silicate, K(2)In(OH)(Si(4)O(10)), has been synthesized by a high-temperature, high-pressure hydrothermal method. It crystallizes in the monoclinic space group P2(1)/m (No. 11) with a = 11.410(1) A, b = 8.373(1) A, c = 11.611(1) A, beta = 112.201(2) degrees, and Z = 4. The structure, which is analogous to that of K(2)CuSi(4)O(10), consists of unbranched vierer 4-fold chains of corner-sharing SiO(4) tetrahedra running along the b axis linked together via corner sharing by chains of trans-corner-sharing InO(4)(OH)(2) octahedra to form a 3-D framework which delimits 8-ring and 6-ring channels to accommodate K(+) cations. The presence of hydroxyl groups is confirmed by IR spectroscopy. The (29)Si MAS NMR exhibits four resonances at -88.6, -90.1, -97.4, and -98.2 ppm corresponding to four distinct crystallographic Si sites. A (1)H --> (29)Si CP/MAS NMR experiment was performed to assign the four resonances.

Journal Article↗