Ionothermal synthesis and crystal structure of a new organic–inorganic hybrid compound: catena‐poly[bis(1‐ethyl‐3‐methylimidazolium) [hepta‐μ‐bromido‐pentacuprate(I)]]

A new organic–inorganic hybrid compound, catena‐poly[bis(1‐ethyl‐3‐methylimidazolium) [μ₅‐bromido‐tri‐μ₃‐bromido‐tri‐μ₂‐bromido‐pentacuprate(I)]], {(C₆H₁₁N₂)₂[Cu₅Br₇]}_n, has been obtained under ionothermal conditions from a reaction mixture containing Ba(OH)₂·8H₂O, Cu(OH)₂·2H₂O, As₂O₅, 1‐ethyl‐3‐methylimidazolium bromide and distilled water. The crystal structure consists of complex [Cu₅Br₇]²⁻ anions arranged in sinusoidal {[Cu₅Br₇]²⁻}_n chains running along the a axis, which are surrounded by 1‐ethyl‐3‐methylimidazolium cations. Three of the five unique Br atoms and one of the three Cu^I atoms occupy special positions with half‐occupancy (a mirror plane perpendicular to the b axis, site symmetry m). The Cu^I ions are in a distorted tetrahedral coordination environment, with four Br atoms at distances ranging from 2.3667 (10) to 2.6197 (13) Å, and an outlier at 3.0283 (12) Å, exceptionally elongated and with a small contribution to the bond‐valence sum of only 6.7%. Short C—H...Br contacts build up a three‐dimensional network. The Cu...Cu distances within the chain range from 2.8390 (12) to 3.0805 (17) Å, indicating the existence of weak Cu^I...Cu^I cuprophilic interactions.     

The formation of an active component in V-Mo-Nb-O catalysts of ethane oxidation and ammoxidation

Summary Genesis of an active component in V-Mo-Nb-O catalysts for the oxidation and ammoxidation of ethane was studied. It was shown that the mixing of aqueous solutions of initial reactants leads to the formation of MoV complexes in the solution and to sedimentation of a binary Nb-Mo compound. The latter serves as the basis for the formation of the catalyst active component phase (a triple V-Mo-Nb compound with a variable composition of Mo₅O₁₄-like structure) during the subsequent treatment in air at 400°C.     

Noetherian varieties in definably complete structures

We prove that the zero-set of a C ^∞ function belonging to a noetherian differential ring M can be written as a finite union of C ^∞ manifolds which are definable by functions from the same ring. These manifolds can be taken to be connected under the additional assumption that every zero-dimensional regular zero-set of functions in M consists of finitely many points. These results hold not only for C ^∞ functions over the reals, but more generally for definable C ^∞ functions in a definably complete expansion of an ordered field. The class of definably complete expansions of ordered fields, whose basic properties are discussed in this paper, expands the class of real closed fields and includes o-minimal expansions of ordered fields. Finally, we provide examples of noetherian differential rings of C ^∞ functions over the reals, containing non-analytic functions.     

Tautomerism of 3‐nitro‐1,2,4‐triazole‐5‐one radical anions

The non‐degenerate tautomers of 3‐nitro‐1,2,4‐triazole‐5‐one (NTO) radical anions were investigated for the first time by an ESR method during electrochemical reduction of NTO in an aprotic medium. Copyright © 2009 John Wiley & Sons, Ltd.     

Classical equations for non-abelian gauge theories in the large-N limit

The classical equations that dominate the large-N limit of non-abelian gauge theories are derived, and it is shown that they satisfy boundary conditions that follow from the quantization of time-independent gauge transformations.     

Stop flow lithography synthesis of non-spherical metal oxide particles

Non-spherical micron and nano-sized particles and their composites have become essential in select application areas of optics,wear resistance,personnel protection,chemical mechanical polishing,and biomedicine.In this paper,the synthesis of composite and ceramic non-spherical particles using stop flow lithography is reported.Precursor suspensions of poly(ethylene glycol) diacrylate,2-hydroxy-2-methylpropiophenone and SiO_2 or Al_2O_3 are prepared.The precursor suspension flows through a microfluidic device mounted on an upright microscope and is polymerized in an automated process.A photomask patterned with transparent geometric features,which define the cross-sectional shapes of the particles,masks the UV light to synthesize micron sized particles.Particles with axial dimensions ranging from 35 to 167 μm were synthesized.Control of device channel depth and objective lens magnification enables the manipulation of the particle size.Composite particles in triangular,square,pentagonal,hexagonal,and circular cross sections were synthesized.Subsequently,the transformation of the composite particles into the corresponding metal oxide particles was achieved through polymer burn-off and sintering.     

Photooxidation of Tetrahydrobiopterin under UV Irradiation: Possible Pathways and Mechanisms

Tetrahydrobiopterin (H₄Bip) is a cofactor for several key enzymes, including NO synthases and aromatic amino acid hydroxylases (AAHs). Normal functioning of the H₄Bip regeneration cycle is extremely important for the work of AAHs. Oxidized pterins may accumulate if the H₄Bip regeneration cycle is disrupted or if H₄Bip autoxidation occurs. These oxidized pterins can photosensitize the production of singlet molecular oxygen ¹O₂ and thus cause oxidative stress. In this context, we studied the photooxidation of H₄Bip in phosphate buffer at pH 7.2. We found that UV irradiation of H₄Bip affected its oxidation rate (quantum yield Φ₃₀₀ = (2.7 ± 0.4) × 10^?3). The effect of UV irradiation at λ = 350 nm on H₄Bip oxidation was stronger, especially in the presence of biopterin (Bip) (Φ₃₅₀ = (9.7 ± 1.5) × 10^?3). We showed that the rate of H₄Bip oxidation linearly depends on Bip concentration. Experiments with KI, a selective quencher of triplet pterins at micromolar concentrations, demonstrated that the oxidation is sensitized by the triplet state biopterin ³Bip. Apparently, electron transfer sensitization (Type‐I mechanism) is dominant. Energy transfer (Type‐II mechanism) and singlet oxygen generation play only a secondary role. The mechanisms of H₄Bip photooxidation and their biological meaning are discussed.