CH3COO Research Articles

Anisotropy in Conformation and Dynamics of a Glycolate Ion Near the Surface of a TiO2 Rutile Crystal Between Its {001} and {110} Planes: A Molecular Dynamics Study

A molecular dynamics simulation was conducted to elucidate the conformation and dynamics of a glycolate ion (CH2(OH)COO–) at the surface of a TiO2 rutile crystal. The simulation was performed for the {001} and {110} planes of the crystal. The results indicate that, for both planes, the conformation and dynamics of the ion are strongly dominated by a layered structure of water on the surface. The simulation suggests that the ion binds to the surface more stably on the {110} plane than on the {001} plane, and that the stable conformation of the ion at the surface differs between the planes: on the {110} plane the carboxyl group of the ion is preferentially oriented toward the surface, whereas on the {001} plane it is oriented toward liquid water. These simulation results are compared with the growth shapes of rutile crystals synthesized in the presence of glycolic acid, and the role of glycolate ions in controlling the morphology of rutile crystals is discussed.

Comparative Investigation of the Ionicity of Aprotic and Protic Ionic Liquids in Molecular Solvents by using Conductometry and NMR Spectroscopy.

Electrical conductivity (σ), viscosity (η), and self-diffusion coefficient (D) measurements of binary mixtures of aprotic and protic imidazolium-based ionic liquids with water, dimethyl sulfoxide, and ethylene glycol were measured from 293.15 to 323.15 K. The temperature dependence study reveals typical Arrhenius behavior. The ionicities of aprotic ionic liquids were observed to be higher than those of protic ionic liquids in these solvents. The aprotic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, [bmIm][BF4 ], displays 100 % ionicity in both water and ethylene glycol. The protic ionic liquids in both water and ethylene glycol are classed as good ionic candidates, whereas in DMSO they are classed as having a poor ionic nature. The solvation dynamics of the ionic species of the ionic liquids are illustrated on the basis of the (1) H NMR chemical shifts of the ionic liquids. The self-diffusion coefficients D of the cation and anion of [HmIm][CH3 COO] in D2 O and in [D6 ]DMSO are determined by using (1) H nuclei with pulsed field gradient spin-echo NMR spectroscopy.

Clinical Characteristics of Patients with Intradialytic Hypertension.

Intradialytic hypertension with a prevalence of 15% among hemodialysis patients is with unknown pathophysiology, demographic, laboratoiy and clinical characteristic of patients, and it's influence on longtenn clinical effects (cardiovascular morbidity and mortality, rate of hospitalization). The aim of the study is to present the clinical, laboratoiy and demographic characteristics of patients with intradialytic hypertension in our dialysis center. Out of 110 hemodialysis patients, 17 patients (15,45%) had intradialytic hypertension - started at a systolic pressure greater than 140 nun Hg or had an increase in systolic pressure more than 10 mm Hg during the session, and 17 patients were nonnotensive or had a drop in blood pressure dining the dialysis. HD were performed 3 times per week with a duration of 4-5 hours, on machines with controlled ultrafiltration and high flux syntetic membrane (polyetersulfon) sterilized with gamma rays. A dialysate with standard electrolytes content was used (Na(+) 138 mmol/L, K(+) 2,0 mmol/L, Ca(++) 1,5 mmol/L, Mg (+)1,0 mmol/L, CH(3)COO(-) 3,0 mmol/L, Cl -110 mmol/1, HCO(3)(-) 35 mmol/L). We analysed the following demographic and clinical characteristics: gender, age, BMI, dialysis vintage, vascular acces, cardiovascular comorbidity (cardiomyopathy, ischemic cardiac disease, peripheral artery disease, heart valve disease), number and type of antihypertensive drugs, weekly dose of erythropoesis - stimulating agent, standard monthly, three and six months laboratoiy analyzes, and sp Kt/V and PCR. Statistical analysis was performed using the statistical software SPSS 17.0. hi both groups men were predominant (IDH group 88.23%, control group 64.07%). The IDH group was older (59.00 ± 7.64 versus 49.00 ± 13.91, p = 0.314) and with lower BMI (p = 0.246) compared to the control group. The DDH patients had significantly lower serum sodium and higher sodium gradient (135.75 ± 2.03 versus 137.33 ± 1.97, p = 0.042; 2.25 ± 1.98 versus 0.66 ± 1.44, p = 0.0267, respestively). All other laboratoiy findings showed no statistically significant differences between the two groups. The IDH group had significantly higher interdialysis weight gain and less effective ultrafiltration individually at each dialysis session compared to the control group (2.23 ± 0.866 versus 2.37 ± 0.69, p = 0.011; 3.87 ± 1,26 versus 3.56 ± 1.18, p = 0.025, respectively). The systolic and mean arterial pressure after the HD were statistically higher in the IDH group. Older age, lower BMI, borderline hyponatremia, higher sodium gradient and smaller ultrafiltration rate are the clinical characteristics of patients with intradialytic hypertension.

Two novel polytitanium precursors containing linear Ti–(OH)2–Ti chains applied for the preparation of titanium dioxide fibers

Two novel precursors, polyacetylacetonatotitanium (PAT) and polyacetictitanium (PET), which can be applied for the preparation of TiO2 fibers, were synthesized by metathetical polycondensations. The fibers of PAT and PET were prepared by sol–gel dry-spinning method. The high-quality and plentiful precursor fibers were easily collected with the diameter of 2–20 μm. The structures of the precursors were characterized and analyzed by elemental analyses, X-ray fluorescence spectrometry, infrared spectral analysis, nuclear magnetic resonance analysis, and thermal analyses. Both PAT and PET are the linear polymers containing Ti(OH)2Ti chains. The coordination number of titanium atom is 8. And each titanium atom is coordinated with six –OHs and one CH3–CO−=C–CO–CH3 (for PAT) or CH3–COO− (for PET). The precursor fibers can be used to prepare TiO2 fibers at 500 °C. The TiO2 fibers exhibit fine photocatalytic degradation activities.

Theoretical study of the infrared frequencies of crystalline methyl acetate under interstellar medium conditions

Identification of methyl acetate in the interstellar medium (ISM) and its spectroscopic studies have prompted us to investigate the structure of crystalline methyl acetate using numerical calculations. Here, we present a theoretical study of the structure of crystalline methyl acetate and its isotopologues and compare the calculated infrared (IR) spectra with the available experimental data. The optimized structure and vibrational properties were calculated using SIESTA software at 0K. In the optimization process, the Perdew–Burke–Ernzerhof functional and conjugate gradient methods were used with double zeta polarization basis functions. After optimization of the periodic structure, the vibrational frequencies and normal modes were calculated within the harmonic approximation. Using the calculated results, we refine the mode assignments of experimental work on crystalline methyl acetate and determine the low frequency modes (below 650cm−1). To investigate the accuracy of the pseudopotential and confirm the IR frequencies, we performed molecular calculations using a periodic model of methyl acetate and its isotopologues using SIESTA and compared them with results obtained from Gaussian 09 (all electron method) calculations. Finally, we assigned the vibrational modes of crystalline CD3–COO–CH3 and CH3–COO–CD3, for which experimental data are not available in the crystalline phase under ISM conditions. For all of the calculation methods, the IR vibrational modes of molecular and crystalline methyl acetate and its isotopologues were in good agreement with the available experimental data and predict the unavailable values.

A Multifunctional Bimetallic Molecular Device for Ultrasensitive Detection, Naked-Eye Recognition, and Elimination of Cyanide Ions.

A new bimetallic Fe(II) -Cu(II) complex was synthesized, characterized, and applied as a selective and sensitive sensor for cyanide detection in water. This complex is the first multifunctional device that can simultaneously detect cyanide ions in real water samples, amplify the colorimetric signal upon detection for naked-eye recognition at the parts-per-million (ppb) level, and convert the toxic cyanide ion into the much safer cyanate ion in situ. The mechanism of the bimetallic complex for high-selectivity recognition and signaling toward cyanide ions was investigated through a series of binding kinetics of the complex with different analytes, including CN(-) , SO4 (2-) , HCO3 (-) , HPO4 (2-) , N3 (-) , CH3 COO(-) , NCS(-) , NO3 (-) , and Cl(-) ions. In addition, the use of the indicator/catalyst displacement assay (ICDA) is demonstrated in the present system in which one metal center acts as a receptor and inhibitor and is bridged to another metal center that is responsible for signal transduction and catalysis, thus showing a versatile approach to the design of new multifunctional devices.

The chemistry of aminoguanidine derivatives – preparation, crystal structure, thermal properties, and molecular docking studies of aminoguanidinium salts of several carboxylic acids

The reaction of aminoguanidine bicarbonate (Amg) with oxamic, oxalic, malonic and sulfoacetic acids yielded (AmgH)H2NOC–COO (1), OOC–CONHNHC(NH2)NH2 (2) (AmgH)HOOC–CH2–COO (3) and O3S–CH2–CONHNHC(NH2)NH2 (4), respectively. For the first time, we studied the salt-forming ability of aminoguanidine with several carboxylic acids, such as oxamic, oxalic, malonic and sulphoacetic acids. We also compared the structural and thermal properties of these salts. Oxamic and malonic acids form only mono-aminoguanidinium salts, whereas oxalic acid mainly forms di-aminoguanidinium oxalate. In addition, oxalic acid forms guanylhydrazido-oxalic acid which exists as zwitter ion. Unlike other acids, sulfoacetic acid readily forms only the zwitter ionic salts (2-guanylhydrazido-oxo-methanesulfonic acid) rather than the usual simple salt. This result may be a result of the highly acidic nature of the sulfonic group, which favors acid catalyzed condensation. More significantly, for the first time, the ability guanylhydrazido-oxalic acid (2) and 2-guanylhydrazido-oxo-methanesulfonic acid (4) to inhibit human butyrylcholinesterase (human BChE) receptor has been studied with a molecular docking approach. The binding of the compounds to human BChE was examined as it is crucial to understanding the biological significance of aminoguanidine derivatives. The compounds were identified and characterized by analytical, FT-IR spectroscopic and thermal studies. Furthermore, the structures of compounds 1, 2 and 4 were confirmed by single X-ray diffraction studies. Compounds 1 and 2 crystallized in a monoclinic crystal system with P21/c and Cc space groups, respectively, whereas compound 4 crystalized in an orthorhombic system with a Pbca space group. All the compounds (1–4) underwent endo- followed by exothermic decomposition in the temperature range from 130 to 600°C to yield gaseous products.

Protic Ionic Liquids Assisted Synthesis and Characterization of Sulfur Nanoparticles and CdS and ZnS Nanomatrials

A series of sulfur nanoparticles (SNPs) was synthesized by wet chemical precipitation method. In this process the initial precursor sulfur powder was heated with poly ethylene glycol-600 (PEG-600) and each of six imidazolium protic ionic liquids(PILs) such as 2-methylimidazolium lactate ((2 mim) CH3CH(OH)COO - ), 1-ethylimidazolium lactate ((1eim) CH3CH(OH)COO - ), 1- butylimidazolium lactate((1bim) CH3CH(OH)COO - ), 2-methylimidazolium glycolate ((2 mim) CH2(OH)COO - ), 1-ethylimidazolium glycolate((1eim) CH2(OH)COO - ),1-butylimidazolium glycolate((1bim) CH2(OH)COO - ) individually for separate process. Where the imidazolium PILs act both as solvent as well as stabilizer. The obtained SNPs are having different morphology and are characterized by UV, IR, XRD, TGA, DTA and SEM with EDAX analysis. Using one of the synthesized SNPs, ZnS and CdS semiconductor nanomaterials were prepared and characterized by XRD and SEM with EDAX analysis.

CH3CO + O2 + M (M = He, N2) Reaction Rate Coefficient Measurements and Implications for the OH Radical Product Yield.

The gas-phase CH3CO + O2 reaction is known to proceed via a chemical activation mechanism leading to the formation of OH and CH3C(O)OO radicals via bimolecular and termolecular reactive channels, respectively. In this work, rate coefficients, k, for the CH3CO + O2 reaction were measured over a range of temperature (241-373 K) and pressure (0.009-600 Torr) with He and N2 as the bath gas and used to characterize the bi- and ter-molecular reaction channels. Three independent experimental methods (pulsed laser photolysis-laser-induced fluorescence (PLP-LIF), pulsed laser photolysis-cavity ring-down spectroscopy (PLP-CRDS), and a very low-pressure reactor (VLPR)) were used to characterize k(T,M). PLP-LIF was the primary method used to measure k(T,M) in the high-pressure regime under pseudo-first-order conditions. CH3CO was produced by PLP, and LIF was used to monitor the OH radical bimolecular channel reaction product. CRDS, a complementary high-pressure method, measured k(295 K,M) over the pressure range 25-600 Torr (He) by monitoring the temporal CH3CO radical absorption following its production via PLP in the presence of excess O2. The VLPR technique was used in a relative rate mode to measure k(296 K,M) in the low-pressure regime (9-32 mTorr) with CH3CO + Cl2 used as the reference reaction. A kinetic mechanism analysis of the combined kinetic data set yielded a zero pressure limit rate coefficient, kint(T), of (6.4 ± 4) × 10(-14) exp((820 ± 150)/T) cm(3) molecule(-1) s(-1) (with kint(296 K) measured to be (9.94 ± 1.3) × 10(-13) cm(3) molecule(-1) s(-1)), k0(T) = (7.39 ± 0.3) × 10(-30) (T/300)(-2.2±0.3) cm(6) molecule(-2) s(-1), and k∞(T) = (4.88 ± 0.05) × 10(-12) (T/300)(-0.85±0.07) cm(3) molecule(-1) s(-1) with Fc = 0.8 and M = N2. A He/N2 collision efficiency ratio of 0.60 ± 0.05 was determined. The phenomenological kinetic results were used to define the pressure and temperature dependence of the OH radical yield in the CH3CO + O2 reaction. The present results are compared with results from previous studies and the discrepancies are discussed.

SERENDIPITOUS SYNTHESIS OF A Cu(OAc)2 COMPLEX VIA CuCl2 CATALYZED OXIDATION OF 2-BUTANONE: SYNTHESIS, CRYSTAL STRUCTURE, AND MAGNETIC BEHAVIOR OF (5-NAP)2(CH3COO)4Cu2∙nH2O (n = 0 AND 2) (5-NAP=2-AMINO-5-NITROPYRIDINE)

A copper (II) catalyzed Baeyer-Villiger reaction of 2-butanone in the presence of oxygen and 2-amino-5-nitropyridine produced crystals of (bis-2-amino-5-nitropyridine)tetraacetatedicopper(II) dehydrate, ( 1 ). 1 and its anhydrous form, (bis-2-amino-5-nitropyridine)tetraacetatedicopper(II), ( 2 ), were then synthesized directly from Cu(CH 3 COO) 2 ∙H 2 O and 2-amino-5-nitropyridine. Crystals of both compounds were grown using slow evaporation, and characterized using IR, combustion analysis, X-ray powder diffraction, single crystal X-ray diffraction, and temperature-dependent magnetic susceptibility measurements. 1 and 2 are both monoclinic and crystallize in the space groups P2 1 /c and C2/m, respectively. 2 exhibits 2-fold disorder in the 2-amino-5-nitropyridine molecule that arises due to symmetry. Both compounds pack in sheets of isolated dimers, and exhibit strong antiferromagnetic interactions within the dimers (J = -442(5) and -471(5) K for 1 and 2 respectively).

Two New Borates Containing [B5O6(OH)4] Clusters, Accompanying a Novel In Situ Organic Reaction Between Ethylenediamine and CH3COO− Group

Two new borate clusters, [C4H11N2O][C4H9N2][B5O6(OH)4]2 (1), [Cd(dien)2][B5O6(OH)4]2 (2, dien = diethylenetriamine), have been obtained under solvothermal conditions and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X-ray diffraction and single-crystal X-ray structural analysis, respectively. Crystal data for 1: monoclinic, P21/c, a = 18.6975(5) A, b = 15.3413(8) A, c = 9.6691(3) A, β = 90.462(3)°, Z = 4. Crystal data for 2: triclinic, P-1, a = 8.6107(4) A, b = 9.3504(4) A, c = 18.9631(4) A, α = 103.798(4), β = 91.940(4)°, γ = 94.134(4)°, Z = 2. They all consist of [B5O6(OH)4]− clusters and further extend to 3-D frameworks via extensive hydrogen-bonding interactions. Interestingly, a novel in situ organic reaction between ethylenediamine and CH3COO− group has been observed during the formation of compound 1.

Influence of the Ni/P ratio and metal loading on the performance of NixPy/SBA-15 catalysts for the hydrodeoxygenation of methyl oleate

A series of high-performance catalysts based on nickel phosphide particles supported on SBA-15 have been synthesized by temperature-programed reduction of a nickel phosphate, previously impregnated in the mesostructured silica support. In these samples the loading of the active phase varied between 10% and 20% in a Ni basis, while nominal Ni/P ratios ranged from 0.5 to 3. The formation of different active phases, Ni2P, Ni12P5 or Ni3P, depending on the P/Ni proportion was verified by X-ray diffraction (XRD). The study of these catalysts by transmission electron microscopy (TEM) and Energy-Dispersive X-ray spectroscopy (EDX) revealed that the majority of the phosphide nanoparticles present a relatively uniform diameter evenly distributed within the SBA-15 channels. All the nickel phosphide catalysts, as well as a reference Ni/SBA-15 catalyst, were tested for the hydrodeoxygenation (HDO) of methyl oleate (C17H33–COO–CH3) in a high pressure continuous flow reactor. This compound was used as a convenient surrogate of triglyceride molecules present in vegetable oils, and following catalytic hydrotreating yields mainly n-alkanes at 30 bars and temperature in the 250–340°C range. In all cases lower contact time and reaction temperature decrease the conversion but favor the formation of C18 alkanes, which is the preferred product in terms of carbon atom economy. In addition, this study reveals that activity and selectivity are affected remarkably by the Ni/P ratio. Maximum conversion is achieved for the catalysts prepared with an initial Ni/P ratio of 1, while selectivity to C18 is larger for the catalyst with an initial Ni/P ratio of 2. These catalysts contain predominantly the Ni2P phase, which seem to be the most active for this process, although the presence of Ni12P5 in the case of the catalysts with Ni/P=2 appears to be also positive. On the basis of the product distribution it can be concluded that both hydrodeoxygenation and decarboxylation/decarbonylation reactions occur simultaneously over the nickel phosphide catalysts, whereas decarboxylation and cracking are the prevailing processes over the Ni/SBA-15 catalyst. Owing to these high yields of long-chain paraffins, SBA-15-supported nickel phosphide catalysts can be considered as a very promising catalyst for the transformation of vegetable oils into green diesel.

Hydrothermal synthesis, structure, and optical properties of two nanosized Ln26 @CO3 (Ln=Dy and Tb) cluster-based lanthanide-transition-metal-organic frameworks (Ln MOFs).

Two Ln26 @CO3 (Ln=Dy and Tb) cluster-based lanthanide-transition-metal-organic frameworks (Ln MOFs) formulated as [Dy26 Cu3 (Nic)24 (CH3 COO)8 (CO3 )11 (OH)26 (H2 O)14 ]Cl ⋅3 H2 O (1; HNic=nicotinic acid) and [Tb26 NaAg3 (Nic)27 (CH3 COO)6 (CO3 )11 (OH)26 Cl(H2 O)15 ]⋅7.5 H2 O (2) have been successfully synthesized by hydrothermal methods and characterized by IR, thermogravimetric analysis (TGA), elemental analysis, and single X-ray diffraction. Compound 1 crystallizes in the monoclinic space group Cc with a=35.775(12) Å, b=33.346(11) Å, c=24.424(8) Å, β=93.993(5)°, V=29065(16) Å(3) , whereas 2 crystallizes in the triclinic space group P$\bar 1$ with a=20.4929(19) Å, b=24.671(2) Å, c=29.727(3) Å, α=81.9990(10)°, β=88.0830(10)°, γ=89.9940(10)°, V=14875(2) Å(3) . Structural analysis indicates the framework of 1 is a 3D perovskite-like structure constructed out of CO3 @Dy26 building units and Cu(+) centers by means of nicotinic acid ligand bridging. In 2, however, nanosized CO3 @Tb26 units and [Ag3 Cl](2+) centers are connected by Nic(-) bridges to give rise to a 2D structure. It is worth mentioning that this kind of 4d-4f cluster-based MOF is quite rare as most of the reported analogous compounds are 3d-4f ones. Additionally, the solid-state emission spectra of pure compound 2 at room temperature suggest an efficient energy transfer from the ligand Nic(-) to Tb(3+) ions, which we called the "antenna effect". Compound 2 shows a good two-photon absorption (TPA) with a TPA coefficient of 0.06947 cm GM(-1) (1 GM=10(-50) cm(4) s photon(-1) ), which indicates that compound 2 might be a good choice for third-order nonlinear optical materials.

Amide-functionalized naphthyridines on a Rh(II) -Rh(II) platform: effect of steric crowding, hemilability, and hydrogen-bonding interactions on the structural diversity and catalytic activity of dirhodium(II) complexes.

Ferrocene-amide-functionalized 1,8-naphthyridine (NP) based ligands {[(5,7-dimethyl-1,8-naphthyridin-2-yl)amino]carbonyl}ferrocene (L(1) H) and {[(3-phenyl-1,8-naphthyridin-2-yl)amino]carbonyl}ferrocene (L(2) H) have been synthesized. Room-temperature treatment of both the ligands with Rh2 (CH3 COO)4 produced [Rh2 (CH3 COO)3 (L(1) )] (1) and [Rh2 (CH3 COO)3 (L(2) )] (2) as neutral complexes in which the ligands were deprotonated and bound in a tridentate fashion. The steric effect of the ortho-methyl group in L(1) H and the inertness of the bridging carboxylate groups prevented the incorporation of the second ligand on the {Rh(II) -Rh(II) } unit. The use of the more labile Rh2 (CF3 COO)4 salt with L(1) H produced a cis bis-adduct [Rh2 (CF3 COO)4 (L(1) H)(2) ] (3), whereas L(2) H resulted in a trans bis-adduct [Rh2 (CF3 COO)3 (L(2) )(L(2) H)] (4). Ligand L(1) H exhibits chelate binding in 3 and L(2) H forms a bridge-chelate mode in 4. Hydrogen-bonding interactions between the amide hydrogen and carboxylate oxygen atoms play an important role in the formation of these complexes. In the absence of this hydrogen-bonding interaction, both ligands bind axially as evident from the X-ray structure of [Rh2 (CH3 COO)2 (CH3 CN)4 (L(2) H)2 ](BF4 )2 (6). However, the axial ligands reorganize at reflux into a bridge-chelate coordination mode and produce [Rh2 (CH3 COO)2 (CH3 CN)2 (L(1) H)](BF4 )2 (5) and [Rh2 (CH3 COO)2 (L(2) H)2 ](BF4 )2 (7). Judicious selection of the dirhodium(II) precursors, choice of ligand, and adaptation of the correct reaction conditions affords 7, which features hemilabile amide side arms that occupy sites trans to the Rh-Rh bond. Consequently, this compound exhibits higher catalytic activity for carbene insertion to the CH bond of substituted indoles by using appropriate diazo compounds, whereas other compounds are far less reactive. Thus, this work demonstrates the utility of steric crowding, hemilability, and hydrogen-bonding functionalities to govern the structure and catalytic efficacyof dirhodium(II,II) compounds.

Doping of MgB 2 Using Molecular Magnets as Precursors

We present the effect of single molecular magnet ([Fe(bpca) 2Dy(NO 3)4] ⋅H 2 O⋅4.5 CH 3 NO 2 and [Mn 2(naften) 2(CH 3COO)(CH 3OH)] ⋅BPh 4) thermolysis on the superconducting properties of polycrystalline MgB 2 samples when inserted and sintered by spark plasma sintering technique. As a result of pyrolysis, Fe- and Dy-magnetic compounds grow within the MgB 2 matrix and give a paramagnetic behavior in normal state, whereas the Mn-based compounds display negligible magnetic properties. We find that the magnetic critical current density of the as-obtained superconducting composites, as well as the pinning mechanism, is dependent on the magnetic background, with a noticeable advantage for the sample with magnetic compounds.

Room temperature Q-band electron magnetic resonance study of radicals in X-ray-irradiated l-threonine single crystals.

In the past, decennia radiation-induced radicals were successfully identified by electron magnetic resonance (EMR) in several solid-state amino acids and sugars. The authors present a room temperature (RT) EMR study of the stable radicals produced by X-ray-irradiation in the amino acid l-threonine (CH₃CH(OH)CH(NH₃ (+))COO(-)). Its chemical structure is similar to that of the well-known dosimetric material l-alanine (CH₃CH(NH₃(+))COO(-)), and radiation defects in l-threonine may straightforwardly be compared with the extensively studied l-alanine radicals. The hyperfine coupling tensors of three different radicals were determined at RT using electron nuclear double resonance. These results indicate that the two most abundant radicals share the same basic structure CH₃(•)C(OH)CH(NH₃(+))COO(-), obtained by H-abstraction, but are stabilised in slightly different conformations. The third radical is most probably obtained by deamination (CH₃CH(OH)(•)CHCOO(-)), similar in structure to the stable alanine radical.

Preparation and Characterization of Cu2ZnSnS4 Nanocrystals and Thin Films

The Cu 2 ZnSnS4(CZTS) nanocrystallites were synthesized by hot injection method with starting materials of copper(II) acetylacetonate [Cu(AcAc)2 ], zinc acetate [Zn(CH3 COO)2 ·2H2 O], tin(II) chloride dehydrate [SnCl2 ·2H2 O], elemental sulfur(S) and dodecanethiol. Then CZTS thin films were prepared by spin coating method. The crystallographic structure, morphology, chemical composition and optical properties of CZTS nanocrystallites and their thin films were characterized by X-ray diffraction(XRD), Raman spectrum(RS), transmission electron microscopy(TEM), scanning electron microscope(SEM) with energy dispersive X-Ray spectroscopy(EDS) and UV-Vis transmittance spectroscopy. The influence of injection temperature on the crystallographic structure, morphology, grain size and chemical composition of CZTS nanocrystallites, and the influence of annealing time on the crystallographic, morphology, chemical composition and optical properties of CZTS thin films were investigated respectively. The results show that the CZTS nanocrystallites synthesized at 180 ℃ were consisted of single phase kesterite with an average grain size 18 nm, while the CZTS thin film after annealing at 500℃ for 2h exhibits an absorption coefficient of 104 cm-1 for the visible light and an optical band gap of 1.45 eV.

ZnO nanorod composite with quenched photoactivity for UV protection application

Zinc oxide (ZnO) nanoparticles (NPs) are common constituents of personal care products including cosmetics and sunscreens because they efficiently absorb ultraviolet (UV) light and appear highly transparent on the skin. However, their inherent photoactivity has an adverse effect to cause photo-induced toxicity to skin cells and needs to be quenched in this context. The photoactivity of ZnO NPs may be reduced through introducing coatings or dopants. Here we propose an alternative approach by synthesizing ZnO nanocomposites using a one-pot wet chemical route. The composite containing ZnO nanorods and layered basic zinc acetate (LBZA) significantly quenched photoactivity and this quenching was attributed to the presence of LBZA. The ZnO nanorods have uniform morphology with an average length of 68.9±19.2nm and an average diameter of 18.4±2.7nm. LBZA has a molecular structure of Zn (OH) 1.6(CH3–COO) 0.4·0.4H2O and was observed as a flake-like thin film. The reported nanocomposite is promising to mitigate the effects of ZnO׳s photoactivity and may provide a means for reducing or eliminating any UV-induced cellular damage.

Self assembly of nanostructured hexagonal cobalt dendrites: an efficient anti-coliform agent

Highly crystalline self assemblies of three dimensional cobalt nanostructures are successfully synthesized by an electrochemical method without any template and surfactants. The cobalt nanostructures obtained by using two precursors, cobalt chloride (CoCl2) and cobalt acetate [(CH3–COO)2Co], shows similar dendritic structure, but with different hierarchical architecture. The architecture of cobalt dendrites (Co-DNDs) prepared by using CoCl2 consists of a long central trunk with hierarchical nanostructures of well aligned dendrites of length in the range 15–20 μm and sub branch is in the range 100–200 nm, while Co-DNDs prepared by using (CH3–COO)2Co additionally shows unique feature of hexagonal nanopoles orthogonal to main trunk. Well defined and highly crystalline Co-DNDs were obtained within thirty seconds at 15 V. Architecture of such well aligned and highly crystalline Co-DNDs with hexagonal fixtures within 30 seconds reaction is hitherto unattempted. The as-synthesized Co-DNDs showed an efficient antibacterial activity against model organisms, Bacillus subtilis NCIM 2063, Escherichia coli NCIM 2931, and fecal coliforms in a sewage waste. The inactivation of bacterial growth is due to the generation of reactive oxygen species (ROS) mediated rupture of cell membrane. An inactivation of fecal coliforms in the sewage wastewater is significant in eradicating water-borne diseases. This is an economical approach as compared to conventional and expensive metal nanoparticles like silver and gold.

Noncovalent fabrication and tunable fusion of block copolymer-giant polyoxometalate hybrid micelles.

The block copolymers (BCs), as structure-directing agents, co-assembling with nanoscale inorganic additives is an important route to fabricate nanostructured hybrid materials. In this work, we present a facile approach to fabricate hybrid micelles composed of BCs and polyoxometalates (POMs), in which the POM clusters are premodified with the groups that can specifically interact with a certain BC block. A representative POM (NH4)42[Mo(132)O(372)(CH(3)COO)(30)(H2O)72] (Mo(132)) is chosen as the example and encapsulated with cationic molecules containing carboxyphenyl groups through electrostatic interactions, and then the resulting hybrid complex can further co-assemble with poly(styrene-block-4-vinylpyridine) (PS-b-P4VP) through hydrogen bonding with the pyridine groups, which leads to the formation of hybrid micelles and the localization of Mo(132) in the micelle cores. The micelles exhibit a high stability despite time and dilution. Furthermore, the fusion of the micelles can be readily adjusted by varying the length of PS blocks, which is promising to be used in constructing polymer-POM hybrid materials with discrete or continuous hybrid domains. This work is based on the electrostatic premodification of POMs and thus its concept is generally suitable for the whole anionic POM system, which may create a large class of BC-POM nanocomposites with tunable structures.