Wayne Ouellette

Cytotoxicity of mesoporous silica nanomaterials.

We here measure the toxicity of MCM-41, a mesoporous silica nanomaterial, two of its functionalized analogs, AP-T, which has grafted aminopropyl groups and MP-T, which has grafted mercaptopropyl groups, and spherical silica nanoparticles (SiO(2)), toward human neuroblastoma (SK-N-SH) cells. Since the particles studied are not soluble in aqueous media, the metric used to report the cytotoxicity of these materials is a new quantity, Q(50), which is the number of particles required to inhibit normal cell growth by 50%. Determining the number of particles per gram of material applied to the cells required both the calculated and experimentally determined surface areas of these nanomaterials. This study shows that Q(50) increases in the order, MCM-41<MP-T<AP-T approximately SiO(2), showing that on a per particle basis, MCM-41 is the most cytotoxic material studied. For the three mesoporous silica materials in this study, cytotoxicity appears related to the adsorptive surface area of the particle, although the nature of the functional group cannot be ruled out. Silica nanospheres have the lowest surface area of the particles studied but since they exhibit a Q(50) value similar to that of AP-T, shape may also be important in the cytotoxicity of these materials.

A Thermally and Hydrolytically Stable Microporous Framework Exhibiting Single‐Chain Magnetism: Structure and Properties of [Co2(H0.67bdt)3]⋅20 H2O

Fixing a hole: Hydrothermal chemistry has been exploited in the preparation of a 3D framework material exhibiting 48% accessible void volume and 1.5% hydrogen uptake by weight at 120 kPa (see picture). The title compound also exhibits single-chain magnetic behavior and reversible changes in magnetic properties upon solvation and desolvation.

Solid state coordination chemistry of metal-1,2,4-triazolates and the related metal-4-pyridyltetrazolates

This short review focuses on the structural chemistry of the coordination polymers of 1,2,4-triazole (Htrz) and the 1,2,4-triazolate ligand (trz) and of 4-pyridyltetrazolate (pt) which can be considered as an expanded analogue of 1,2,4-triazolate. The structures are discussed in terms of some common building blocks and the sorptive and magnetic properties of these materials.

Solid-state coordination chemistry of copper(II) tetrazolates: anion control of frameworks constructed from trinuclear copper(II) building blocks.

The products of the reactions of copper(II) starting materials with 4-pyridyltetrazole (4-Hpt) in N,N-dimethylformamide (DMF)/methanol solutions are determined by the anion identity and concentration. In the absence of chloride, the 3-D open-framework material [Cu(3)(OH)(3)(4-pt)(3)(DMF)(4)].5DMF.3MeOH (1.5DMF.3MeOH) is isolated, while variations in the chloride concentration yield the 2-D and 3-D materials, 2 and 3, respectively. All three structures exhibit trinuclear copper(II) building blocks: the triangular {Cu(3)(mu(3)-OH)}(5+) core in 1 and {Cu(3)Cl(4)(4-pt)(4)(4-Hpt)(2)}(2-) and {Cu(3)Cl(2)(4-pt)(8)}(4-) chains in 2 and 3, respectively. All three materials display microporosity, which is highly dependent on the method of sample preparation.

Construction of metal-organic oxides from molybdophosphonate clusters and copper-bipyrimidine building blocks.

A series of organic-inorganic hybrid materials of the copper(II)-molybdophosphonate family have been prepared using conventional hydrothermal conditions. The reactions of MoO(3), copper(II) acetate, bipyrimidine (bpyr), a phosphonic acid, and water at temperatures below 160 degrees C and in the presence of a mineralizer such as acetic acid or HF provided crystalline samples of materials of the general class {Cu(2)(bpyr)}(4+)/Mo(x)O(y)-phosphonate. The recurrent themes of the structures are the presence of the binuclear {Cu(2)(bpyr)}(4+) and pentanuclear {Mo(5)O(15)(O(3)PR)(2)}(4-) building blocks. For the alkylphosphonate-containing materials, [{Cu(2)(bpyr)(2)}Mo(5)O(15)(O(3)PCH(3))(2)].2.5H(2)O (1.2.5H(2)O) is two-dimensional and exhibits {Cu(bpyr)}(n)(2n+) chains, while [{Cu(2)(bpyr)(H(2)O)}Mo(5)O(15)(O(3)PCH(2)CH(3))(2)] (2) is three-dimensional. The diphosphonate series of materials {{Cu(2)(bpyr)}(4+)[Mo(5)O(15){O(3)P(CH(2))(n)PO(3)}](4-) with n = 2-6 (4, 5, 7-9) in all cases contain the characteristic [Mo(5)O(15){O(3)P(CH(2))(n)PO(3)}](n)(2n+) chains, linked through {Cu(2)(bpyr)}(4+) rods into three-dimensional frameworks. When n = 1, the three-dimensional phase [{Cu(2)(bpyr)}MoO(2)(HO(3)PCH(2)PO(3))(2)].2H(2)O (3.2H(2)O) is obtained, the exclusive example of a structure constructed from isolated {MoO(6)} polyhedra rather than pentamolybdate clusters. The Ni(II)-containing phase [{Ni(2)(bpyr)(H(2)O)(4)}Mo(5)O(15){O(3)P(CH(2))(3)PO(3)}].9H(2)O (6.9H(2)O) was also prepared and compared to the structure of the Cu(II) analogue, [{Cu(2)(bpyr)(H(2)O)(4)}Mo(5)O(15){O(3)P(CH(2))(3)PO(3)}].3H(2)O (5.3H(2)O). Magnetic susceptibility studies of the compounds revealed that the magnetic behavior was consistent in all cases with antiferromagnetically coupled dimers. However, the magnitude of the exchange coupling was clearly dependent on the orientation of the M(II) mean equatorial or basal planes relative to the bipyrimidine plane. Thus, when the metal and bipyrimidine planes are nearly coplanar, the J values are in the -77 to -87 cm(-1) range, while J values of -2 to -5 cm(-1) are observed for the compounds with out-of-plane orientations.

Solid state coordination chemistry of microporous metal–organic frameworks of the cadmium(II)–4-pyridyltetrazolate family: the structural influences of chloride incorporation

While the metal-organic framework [Cd(4)(OH)(2)(4-pt)(6)(DMF)(4)].12DMF (.12DMF) (4-pt = 4-pyridyltetrazolate) is constructed from binuclear metal subunits, linked into porous {Cd(2)(OH)(DMF)(2)(4-pt)(3)}(6) cages, introduction of increasing concentrations of chloride yields the 3-D framework materials, [Cd(4)Cl(3)(4-pt)(4)(OH)(DMF)(3)].8DMF.14MeOH (.8DMF.14MeOH) and [Cd(5)Cl(6)(4-pt)(DMF)(2)(H(2)O)(2)].10DMF (.10DMF), constructed from tetranuclear and chain building blocks, respectively.

Cryogenic Terahertz Spectrum of (+)-Methamphetamine Hydrochloride and Assignment Using Solid-State Density Functional Theory

The cryogenic terahertz spectrum of (+)-methamphetamine hydrochloride from 10.0 to 100.0 cm(-1) is presented, as is the complete structural analysis and vibrational assignment of the compound using solid-state density functional theory. This cryogenic investigation reveals multiple spectral features that were not previously reported in room-temperature terahertz studies of the title compound. Modeling of the compound employed eight density functionals utilizing both solid-state and isolated-molecule methods. The results clearly indicate the necessity of solid-state simulations for the accurate assignment of solid-state THz spectra. Assignment of the observed spectral features to specific atomic motions is based on the BP density functional, which provided the best-fit solid-state simulation of the experimental spectrum. The seven experimental spectral features are the result of thirteen infrared-active vibrational modes predicted at a BP/DNP level of theory with more than 90% of the total spectral intensity associated with external crystal vibrations.

Hydrothermal chemistry of vanadium oxides with aromatic di- and tri-phosphonates in the presence of secondary metal copper(II) cationic complex subunits

The hydrothermal chemistry of the copper-organonitrogen ligand/vanadium oxide/aromatic phosphonate system has been studied. Not only was HF required to induce crystallization, but product composition was highly dependent on the HF/V ratio of the reactions. At relatively low concentrations of HF/V of 6:1, materials of the Cu(II)-ligand/VxOy/organophosphonate type were observed, namely, [{Cu(phen)}2V2O5(O3PC6H4PO3)] (1), [Cu(phen)VO2(HO3PC6H4PO3)] (2), [{Cu(terpy)}2V2O5(O3PC6H4PO3)] (3), [{Cu(phen)(H2O)}VO2(HO3PC6H4PO3)] (6), [{Cu(phen)}VO2(HO3PC6H4PO3)] (7a and 7b), [Cu(C5H4NCO2)2V2O4(HO3PC6H4POH3)] (8), [Cu(bpy)VO2 {(HO3P)3C6H3}]·1.5H2O (12·1.5H2O), [{Cu(bpy)}2V3O7{(O3P)2C6H3PO3H}] (13) and [Cu(phen)V3O6(H2O){(O3P)2C6H3(PO3H)}] (14). When the HF concentration was raised, materials incorporating fluoride anion were observed; that is, compounds of the Cu(II)-ligand/VxOyFz/organophosphonate type: [{Cu(bpa)}2VO2F(H2O)(O3PC6H4PO3)]·H2O (4), [{Cu(bpa)}2V2O4F2(O3PC6H4PO3)] (5), [{Cu(bpy)}2V2O4F2(O3PC6H4PO3)] (9), [{Cu(terpy)}2V3O6F(HO3PC6H4PO3)2] (10), [{Cu(bpa)}2V2O4F2(O3PC6H4PO3)] (11). At HF/V concentrations of 25:1 or greater, vanadium free products, Cu(II) ligand/organophosphonate, were obtained: [Cu(C5H4NCO2)2(H2O3PC6H4PO3H2)]·H2O (15·H2O), [Cu(C5H4NCO2)2(H2O3PC6H4PO3H2)] (16), [Cu(bpy)(H2O){(HO3P)2C6H3(PO3H2)}] (17), [Cu(bpy){(HO3P)2C6H3(PO3H2)}]·H2O (18·H2O), [Cu(phen){(H2O3P)C6H3(PO3H)2}]·2H2O (19·2H2O) and [Cu(bpa){H2O3PC6H3(PO3H)2}]·H2O (20·H2O). The structural chemistry is unusually diverse with the Cu(II) ligand/VxOy/organophosphonate series exhibiting one-, two- and three-dimensional structures with a variety of copper-vanadate and vanadophosphonate substructures. The structural chemistry is discussed in relation to other examples of materials of the Cu(II) ligand/VxOy/organophosphonate and Cu(II) ligand/VxOyFz/organophosphonate families.

Noncovalent interactions in paired DNA nucleobases investigated by terahertz spectroscopy and solid-state density functional theory.

Cocrystallized adenine and thymine derivatives, along with the pure monomeric crystals, were investigated by terahertz spectroscopy and solid-state density functional theory (DFT). The methylated nucleobase derivatives crystallize in planar hydrogen-bonded adenine-thymine pairs similar to the manner found in DNA. The spectra obtained for 1-methylthymine, 9-methyladenine, and the 1:1 cocrystal in the range of 10-100 cm(-1) clearly demonstrate that absorptions in this spectral range originate from the uniquely ordered assembly and the intermolecular interactions found in each individual crystal system. The quality of spectral reproduction for the DFT simulations of each system was clearly improved by the inclusion of an empirical correction term for London-type dispersion forces to the calculations. Notably, it was found that these weak dispersion forces in the adenine-thymine cocrystal were necessary to produce a properly converged crystal structure and meaningful simulation of the terahertz vibrational spectrum.

Redetermination of cyclo-trimethyl­ene­trinitramine

The redetermined structure of 1,3,5-trinitro-1,3,5-triazacyclohexane, C3H6N6O6, at 90 (2) K has orthorhombic (Pbca) symmetry. It is of interest with respect to energetic compounds. The structure was originally investigated through X-ray diffraction by Hultgren [(1936). J. Chem. Phys. 4, 84]. Later X-ray investigations were completed by McCrone [(1950). Anal. Chem. 22, 954–955] and Harris, Reed & Gluyas [(1959). AFOSR-TR-59-165 Ohio State University Research Foundation, Columbus, Ohio, USA]. A single-crystal neutron diffraction study was performed by Choi & Prince [(1972). Acta Cryst. B28, 2857–2862] to ascertain the H-atom positions, which had not been defined by the earlier X-ray diffraction studies. All previous studies were performed at or near room temperature. The structure provided is the α polymorph of the title compound. The ring atoms are arranged in the chair conformation with two nitro groups occupying pseudo-equatorial positions and the remaining nitro group is axial. The crystal packing is stabilized by close intramolecular interactions from one H atom in each methylene group to O atoms of adjacent nitro groups, ranging from 2.251 to 2.593 Å.