Synthesis,Crystal Structure,and Characterization of 2-Phenyl-N-(pyrazin-2-yl)Acetamide

The title compound, 2-Phenyl-N-(pyrazin-2-yl)acetamide, C₁₂H₁₁N₃O, was prepared by the coupling reaction and the product was crystallized by using toluene and methanol mixture(1:1) The structure of the compound was confirmed by elemental analysis, FTIR, ¹H NMR, thermogravimetric analysis, differential thermal analysis, UV-Visible spectroscopy, and single-crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P 2₁/c with the following unit-cell parameters: a = 8.1614(10), b = 14.9430(13), c = 9.3877(9) Å, β = 103.653(12)°, and Z = 4. The crystal structure was solved by direct methods using single-crystal X-ray diffraction data collected at room temperature and refined by full-matrix least-squares procedures to a final R-value of 0.0465 for 1486 observed reflections. An intramolecular C&sbnd;H···O hydrogen bond generates an S(6) graph-set motif. In the crystal, molecules are linked by N&sbnd;H···O and C&sbnd;H···O hydrogen bonds, forming a two-dimensional network.     

Synthesis,Crystal Structure,and Characterization of New 2,4,5-Triphenyl Imidazole: 4,5-Diphenyl-2-(3,4,5-trimethoxyphenyl)-1H-imidazole

The substituted triarylimidazole, C₂₄H₂₂N₂O₃, was prepared from the three-component one-pot condensation reaction and the product was crystallized by using dimethylformamide. The structure of the compound was confirmed by elemental analysis, FT-IR, thermogravimetric analysis (TGA), UV-Visible and single-crystal X-ray diffraction. The compound crystallizes in the monoclinic crystal system in the space group P2₁/c with unit cell parameters a = 10.509(3) Å, b = 18.748(5) Å, c = 22.016(6) Å, β = 90.844(5)°, and Z = 8. The crystal structure of the compound was stabilized by the inter-molecular interactions of types N–H???N, C–H???O, and C–H???N, and intra-molecular interactions of the type C–H???O. The structure also involves C–H???π interactions.     

Characterization of chemical information and morphology for in‐depth oxide layers in decarburized electrical steel with glow discharge sputtering

A combination of scanning electron microscopy, X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy with a sampling method by glow discharge sputtering was successfully employed to characterize the chemical information and microscopic features of oxide layers formed during decarburization annealing of electrical steel in the depth direction at high resolution. The discontinuous surface oxides consisted of SiO₂, (Fe,Mn)SiO₃/(Fe,Mn)₂SiO₄, and FeO. SiO₂ embedded in the (Fe,Mn)₂SiO₄ at the surface may be developed by the preferential nucleation and growth kinetics. The discrete or often relatively spherical oxides of internal oxidation by the energetically favorable surface effect were identified as a mixture of SiO₂ and (Fe,Mn)₂SiO₄ at a depth of ~0.5 µm from the surface. The oxides of networks and small particles at a depth greater than ~1 µm were solely silica, of which the morphologies were possibly caused by the enhanced diffusion of oxygen atoms and Si atoms at grain boundaries or sub‐grain boundaries. The equilibrium and kinetic considerations served by theoretical calculations were introduced to understand the formation and behavior of the observed in‐depth oxidation. Copyright © 2013 John Wiley & Sons, Ltd.     

The degradation of poly(vinyl acetate) as a material for design objects: A multi-analytical study of the Cocoon lamps. Part 2

After the systematic study of poly(vinyl acetate) degradation presented in part 1, this work reports results from the analysis of polymeric materials from five Italian design lamps from the 1960s made of the material known as cocoon. Micro- and non-destructive molecular spectroscopic techniques have been applied directly on the object surfaces using an optical fibre probe and through examination of micro-samples: the combined use of Fourier-transform infrared spectroscopy (FTIR), pyrolysis gas-chromatography/mass-spectrometry (py-GC/MS) and Fluorescence spectroscopy allowed the assessment of the material composition and the chemical modifications of the polymers related to on-going deterioration processes. Fluorescence spectroscopy proved particularly sensitive for the detection of variations in composition among lamps and between areas on the same object, and was used to classify objects in different groups using principal component analysis of excitation emission spectra. Specific degradation products have been mapped using FTIR on micro-samples. Moreover, the interpretation of the emission spectra of the studied polymeric lamps suggests that fluorescence spectroscopy can be used for non-destructive monitoring of the degradation of historical polymeric objects.     

pH Induced Partitioning and Interactions of Ciprofloxacin Hydrochloride with Anionic Surfactant Sodium Dodecyl Sulfate Using Ultraviolet and Fourier Transformed Infrared Spectroscopy Study

Ultraviolet (UV) and Fourier transformed infrared (FTIR) spectra of ciprofloxacin hydrochloride (Cpf) were studied under different pH conditions. The effect of aqueous, strong acidic, (pH 0.5–1.0) and a basic (pH 9.2) conditions on spectral behavior of Cpf was investigated in aqueous as well as in micellar environment of sodium dodecyl sulfate (SDS). Cpf shows partitioning from aqueous to micellar phase in a strong acidic as well as in a basic environment. Cpf shows no partitioning or binding to micelle in aqueous phase. Conductivity studies show that critical micelle concentration of SDS is increased with increasing concentration of Cpf. Different sites are responsible for binding under different pH conditions.     

Functionalization by Cold Plasmas of Polymer Model Surfaces (Hexatriacontane and Octadecyloctadecanoate) Studied by Contact Angle Measurements,XPS, and FTIR Spectroscopy

Abstract

Surface functionalization by argon or oxygen RF plasmas (13.56 MHz) of polymer model compounds, namely hexatriacontane (C₃₆H₇₄) and octadecyloctadecanoate [OOD, CH₃(CH₂)₁₆COO(CH₂)₁₇CH₃, was studied using contact angle measurements, XPS, and FTIR-ATR. In order to gain a better insight into the plasma-surface interaction mechanisms, the effects of the main plasma parameters (treatment time, power, pressure, and flow rate) on functionalization were investigated. It was shown that an argon plasma is more efficient than an oxygen plasma and that the ester-containing model compound incorporated less oxygen than the paraffinic one. After 10 seconds of treatment, contact angle measurements showed that none of these plasma parameters affect in any way the properties of the uppermost surface layer; these depend only on the nature of the sample and on the gas used in the plasma. On the other hand, ESCA, which allows a 70-Å in-depth probing, reveals the influence of the plasma parameters on both types of samples. IR, which probes to a much greater depth, evidences an evolution only for treated OOD samples. Interpretations are proposed for the effect of the plasma parameters on functionalization.     

Studies on Ultrasonic Degradation and Block Copolymerization of Hydroxyethylcellulose and Poly(ethylene Oxide)

The ultrasonic degradation of hydroxyethylcellulose (HEC) and poly (ethylene oxide) (PEO) in aqueous solution, and the copolymerization of HEC with PEO were studied. The structure of the copolymer was identified by DTA, IR, MS, x-ray diffraction, and polarizing microscopy. The copolymer prepared is mainly block. The copolymer formed amounts to 55.07% by irradiating 0.5% HEC/PEO aqueous solution for a period of 10 min at 25°C and 18.2 kHz with 2.5 A input current on a reversed main circuit.     

Physicochemical Characteristics of Styrene-Butadiene Latex- modified Mortar Composite vis-à-vis Preferential Interactions

The interaction between styrene-butadiene rubber (SBR) film and the ions from C₂S and C₃S hydration of Portland cement mortar composites has been evaluated by Fourier Transform Infrared Spectroscopy (FTIR), and the morphology of the composites characterized with scanning electron microscopy (SEM). The specimen used was cured for 28 days. FTIR spectrum supports the interaction of SBR with cement in the composite. Compressive strength, bulk density and water absorption properties of the cured composites were tested. Addition of SBR latex in Portland cement mortar increases the compressive strength and decreases the water absorption. Bulk density study revels interface formation in the composite. The role of the interface in relation to compressive strength of the composite has been discussed. A simple Matrix System model is shown to account composition dependence of bulk density.     

Evidences for Chelating Complexes of Lithium with Phenylphosphinic and Phenylphosphonic Acids: A Spectroscopic and DFT Study

Abstract

Lithium complexes were prepared with phenylphosphinic and phenylphosphonic acids. The complexes were studied in the solid state using Fourier transform infrared spectroscopy spectroscopy and in solution (methanol) using ¹H, ¹³C, and ³¹P Nuclear magnetic resonance spectroscopy (NMR) spectroscopy; the most preferred structures of the complexes were determined by density functional theory (DFT) computational method. Although methanol has a strong solvation effect on lithium ions and ligands, which causes dissociation of the complexes, significant changes of the NMR spectra of the complexes (relative to those of the free ligands) were observed. The new spectroscopic results indicate the presence of the phenylphosphinic acid tautomer (I: C₆H₅PH(?O)OH) rather than that of phenyl-phosphorous acid (II: C₆H₅P(OH)₂) in deuterated methanol showing PH/PD exchange. On the other hand, tautomer I predominates in the complex with lithium without showing PH/PD exchange. The DFT calculations predict that tautomer I is the preferred structure in the case of free ligand and lithium complex. The absence of a PH/PD exchange in the complex is due to the formation of a chelating complex, rather than of a simple salt between lithium ion and the two oxygen atoms of I, which prevent tautomerization of I into II. DFT calculations support the formation of lithium chelating complexes. The lithium ion was found to affect the spectroscopic properties of phenylphosphinic acid more dramatically than those of phenylphosphonic acid.     

UV‐curable acrylate‐based nanocomposites: effect of polyaniline additives on the curing performance

Composites of nanostructured polyaniline (PANI) conducting polymer in a polyester acrylate (PEA) formulation were made to provide conductive organic coatings. The effect of the presence and amount of PANI on the photocuring performance of the ultraviolet (UV)‐curable acrylate system has been investigated employing real‐time Fourier transform infrared spectroscopy as the main technique. Longer initial retardation of the radical polymerization and lower rates of cross‐linking reactions were observed for dispersions containing PANI of higher than 3wt.%. The PEA/PANI samples were more affected than the neat PEA resin by the changes in UV light intensity and oxygen accessibility during UV curing. Samples with higher PANI content, of up to 10wt.%, were tested and could be partially cured even at UV light intensities as low as 2 mW cm^?2 when the oxygen replenishment into the system was inhibited. Thermal analysis revealed that the presence of PANI did not induce any significant change in Tg of the cured system, meaning that early decrease in mobility and vitrification is not the reason for lower ultimate conversion of the dispersions with higher PANI content compared with the neat PEA resin. Curing under strong UV lamps, of 1.5 W cm^?2 intensity, made it possible to reach high degrees of conversion on films with similar mechanical properties independent of the PANI content. Copyright © 2013 John Wiley & Sons, Ltd.