Synthesis,characterization, thermal stability,conductivity, and band gaps of substitute oligo/polyamines or polyphenol

In this study, the oxidative polycondensation reaction conditions of 3,5‐dichloroaniline (DCA), 3,4,5‐trimethoxyaniline (TMA), 3,5‐bis(trifluoromethyl)aniline (BTFMA), and 4‐{[(3,5‐dichlorophenyl)imino]methyl}phenol (DCPIMP) were studied by using NaOCl oxidant in an aqueous alkaline medium between 40 and 90°C. The structures of the synthesized monomer and polymer were confirmed by FT‐IR, Ultraviolet–visible (UV–vis), ¹H‐NMR, and ¹³C‐NMR and elemental analysis. The characterization was made by TGA–DTA, size exclusion chromatography (SEC), and solubility tests. At the optimum reaction conditions, the yields of oligo‐3,5‐dichloroaniline (ODCA), poly‐3,4,5‐trimethoxy aniline (PTMA), oligo‐3,5‐bis(trifluoromethyl)aniline (OBTFMA), and poly‐4‐{[(3,5‐dichlorophenyl) imino]methyl} phenol (PDCPIMP) were found to be 98, 48, 80, and 83% in using NaOCl oxidant. According to the SEC analysis, the number‐average molecular weight (M_n), weight‐average molecular weight (M_w) and polydispersity index (PDI) values of ODCA, PTMA, and OBTFMA were found to be 2200, 3800 g mol^?1, and 1.727; 4700, 7500 g mol^?1, and 1.596; and 1690, 1950 g mol^?1, and 1.154, respectively. According to TG analysis, the weight losses of ODCA, PTMA, OBTFMA, and PDCPIMP were found to be 78.55, 54.18, 99.38, and 59.70% at 1000°C, respectively. PTMA showed higher stability against thermal decomposition. Electrical conductivity of the polymers was measured, showing that the polymer is a typical semiconductor. The highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) and electrochemical band gaps ( ) of ODCA, PTMA, OBTFMA, and PDCPIMP were calculated from their absorption edges of cyclic voltammograms. The optical band gaps (E_g) values of all compounds were calculated from UV–vis measurements. Copyright © 2009 John Wiley & Sons, Ltd.     

On Lyapunov-type inequality for quasilinear systems

In this paper, we sketch some recent developments in the theory of Lyapunov-type inequalities and present some new results relating to a quasilinear system, special cases of which contain some well-known differential equations such as half-linear and linear equations. Our result generalize the Lyapunov-type inequality given in [18].     

Metabolic infrastructure of pregnant women with methylenetetrahydrofolate reductase polymorphisms: A metabolomic analysis

The aim of this study was to demonstrate the altered metabolic infrastructure of pregnant women with methylenetetrahydrofolate reductase (MTHFR) polymorphisms at first trimester and during delivery. Eight singleton pregnant women with MTHFR polymorphisms were compared with 10 normal pregnant women. Maternal blood samples were obtained twice during their pregnancy period (between the 11th and 14th gestational weeks and during delivery). Metabolomic analysis was performed using GC–MS. The GC–MS based metabolomic profile helped identify 95 metabolites in the plasma samples. In the MTHFR group, the levels of 1-monohexadecanoylglycerol, pyrophosphate, benzoin, and linoleic acid significantly decreased (P ˂ 0.05 for all), whereas the levels of glyceric acid, l -tryptophan, l -alanine, l -proline, norvaline, l -threonine, and myo-inositol significantly increased (P ˂ 0.01 for the first two metabolites, P ˂ 0.05 for the others) at 11–14 gestational weeks. Conversely, the levels of benzoin, 1-monohexadecanoylglycerol, pyruvic acid, l -proline, phosphoric acid, epsilon-caprolactam, and pipecolic acid significantly decreased in the MTHFR group, whereas metabolites such as hexadecanoic acid and 2-hydroxybutyric acid increased significantly in the study group during delivery. An impaired energy metabolism pathway, vitamin B complex disorders, tendency for metabolic acidosis (oxidative stress), and the need for cell/tissue support seem prevalent in pregnancies with MTHFR polymorphisms.     

Cycloaddition of Acyclic Nitrones with Phenyl Isocyanate: Synthesis and Ring‐Opening Reactions of 1,2,4‐Oxadiazolidin‐5‐ones

The cycloaddition of nitrones with unsubstituted or electron‐donating substituents on the C‐phenyl 1a,c,f with phenyl isocyanate proceeds smoothly for a short time with high yields to give the corresponding 1,2,4‐oxadiazolidinone 2, and 1b,d,e with electron‐withdrawing substituents gave the corresponding oxadiazolidinone in moderate yields after prolonged heating. Oxadiazolidinones 2a,c,f undergo diethylamine‐induced fragmentation for a short time to give the corresponding Schiff bases, and oxadiazolidinones 2b,d,e remain unchanged in these conditions. Prolonged heating of 2d,e in the presence of diethylamine led to complex mixtures. In the case of 2b the corresponding amidine was the main product of the reaction.     

A novel and synthetically facile coumarin-thiophene-derived Schiff base for selective fluorescent detection of cyanide anions in aqueous solution: Synthesis,anion interactions,theoretical study and DNA-binding properties

A colorimetric and fluorescent chemosensor (chemosensor 2) for the detection of cyanide anions in aqueous solution has been designed and synthesized in high yield. The sensing mechanism of the chemosensor was verified via UV–vis, fluorimetric, and NMR titrations, and was theoretically explained using DFT and TD-DFT calculations. The chemosensor could optically discriminate the presence of fluoride ions over other anions by a color change from yellow to red with an enhancement of pink fluorescence in DMSO. However, it showed strong green fluorescence when CN^? was added to a mixture of DMSO/water (6:4 v/v). Thus, the chemosensor can be employed in selective detecting of CN^? besides other interference anions (F^?, AcO^? and H₂PO₄^?) in aqueous solution. Moreover, 2 can be used to detect CN^? at a concentration as low as 0.32?μM, which is lower than the WHO guideline (2.7?μM) for cyanide. A low quantity of CN^? (1.08?μM) can be detected and quantified using the prepared chemosensor. Moreover, the UV–vis and fluorescence spectroscopy studies of the interactions between 2 and dublex DNA revealed intercalative binding of calf thymus DNA to the chemosensor.     

<Emphasis Type="Italic">N</Emphasis>-Propylphthalimide-substituted bis-(NHC)PdX<Subscript>2</Subscript> complexes: synthesis,characterization and catalytic activity in direct arylation reactions

Palladium-catalyzed direct arylation of heteroaromatics has become a popular method for producing carbon–carbon bonds via C–H bond activation. A wide diversity of heteroaromatics such as furan, thiophenes and thiazoles can be used for this reaction. This paper reports the synthesis of N-propylphthalimide-substituted bis-(NHC)PdX₂ complexes (NHC = N-heterocyclic carbene), and their catalytic activity in direct arylation reactions. The complexes have been prepared from Ag(I)NHC precursors by transmetallation and characterized by spectroscopy and elemental analysis. The bis-(NHC)PdX₂ complexes show excellent activity as catalysts in the direct arylation reactions of 2-n-butylfuran, 2-n-butylthiophene and 2-isopropylthiazole.     

Synthesis,spectroscopic and structural characterisation of two p-nitrobenzamide compounds: experimental and DFT study

The title molecules, N-(1,5-dimethyl-3-oxo-2-phenyl-1H-3-(2H)-pyrazolyl)4-nitrobenzamide (C₁₈H₁₆N₄O₄·H₂O) (I) and 2,2-dimethyl-3-(4-nitrobenzoyl)-5-(phenylamino)-2,3-dihydro-1,3,4-thiyadiazole (C₁₇H₁₆N₄O₃S) (II), were prepared and characterised by ¹H NMR, ¹³C NMR, infrared spectroscopy (IR) and structural X-ray diffraction (XRD) techniques. The molecular geometries, vibrational frequencies of the title compounds in the ground state have been calculated by using the density functional theory (DFT) method with 6-31G(d) basis set, and compared with the experimental data. The calculated results showed that the optimised geometries from the DFT method agree with the X-ray structures well for both compounds. Theoretical calculations of harmonic vibration frequencies are in good agreement with experimental results. To determine conformational flexibility, the molecular energy profiles of the title compounds were obtained. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis and thermodynamic properties of the title compounds were investigated by theoretical calculations.     

Effects of anthropological factors on the metal accumulation profiles of sea cucumbers in near industrial and residential coastlines of İzmir,Turkey

This study details the metal and metalloid accumulation profiles of three species of sea cucumbers (Holothuriamammata, Holothuriapolii and Holothuriatubulosa) native to Alia?a and Ild?r (?zmir, Turkey), two regions that are representative of industrial and residential districts, respectively. A total of 11 elements were analysed (Fe, Cu, Mn, Zn, Cr, Co, V, Ni, Cd, Pb and As) from gut and body wall tissues of holothurians and in sediment samples. The Mann–Whitney U analysis revealed statistical difference between locations and tissues. Accumulations of Alia?a samples were significantly higher than Ild?r samples with respect to Zn, V, Mn, Cr, Fe and Co while accumulations were significantly higher in the gut than body wall regardless of the region for all elements tested. The correlation analysis showed more and stronger correlations in the gut than in the body wall. In addition, metal(loid) concentrations in the sediment were found to correlate strongly with these in the sea cucumber gut. The cluster analysis displayed totally different element accumulation pattern for Alia?a and Ild?r in the both tissues which indicate that anthropogenic effects start to alter the bioaccumulation of metal(loids). Biota-sediment accumulation factors (BSAF) and metal contamination index were calculated to determine the extent of metal(loid) uptake and to compare total elemental accumulation at each region. Gut tissue elemental BSAF is higher than body wall for all elements at both areas. Cd has the highest value with 5.582 (gut tissue) and the lowest are Ni, V and Cr with 0.001 (body wall tissue). In addition, sediment results were compared with previous studies and sediment quality guidelines and found to exceed the lowest effect level (LEL) values for As and Ni.     

Measuring striving for understanding and learning value of geometry: a validity study

The current study aimed to construct a questionnaire that measures students’ personality traits related to striving for understanding and learning value of geometry and then examine its psychometric properties. Through the use of multiple methods on two independent samples of 402 and 521 middle school students, two studies were performed to address this issue to provide support for its validity. In Study 1, exploratory factor analysis indicated the two-factor model. In Study 2, confirmatory factor analysis indicated the better fit of two-factor model compared to one or three-factor model. Convergent and discriminant validity evidence provided insight into the distinctiveness of the two factors. Subgroup validity evidence revealed gender differences for striving for understanding geometry trait favouring girls and grade level differences for learning value of geometry trait favouring the sixth- and seventh-grade students. Predictive validity evidence demonstrated that the striving for understanding geometry trait but not learning value of geometry trait was significantly correlated with prior mathematics achievement. In both studies, each factor and the entire questionnaire showed satisfactory reliability. In conclusion, the questionnaire was psychometrically sound.