Synthesis and properties of novel poly(N-oxyimide)s

Novel poly(N-oxyimide)s (PNOI) were synthesized by the room temperature polycondensation of N,N′-dihydroxypyromellitimide (I) with dichloro compounds in N,N-dimethylformamide (DMF) in the presence of triethylamine both as base as well as catalyst. The dichloro compounds used were 1,4-bis(chloromethyl)-2,5-dimethylbenzene (II), 1,5-bis(chloromethyl)-2,4-dimethylbenzene (III), 1,4-bis(chloromethyl)-2,5-dimethoxybenzene (IV) and 1,4-dichlorobut-2-yne (V). Polymer synthesis, characterization, and properties such as density, viscosity, solubility, crystallinity, and thermal stability were described. Two model compounds, viz. (i) MNOI-1 from N-hydroxyphthalimide and a dichloro compound (III), (ii) MNOI-2 from I and benzyl chloride were also synthesized to confirm the formation of polymers. The polymers thus obtained had high intrinsic viscosities in the range 1.09–1.18 dl/g. The thermal decomposition of the polymers started around 260°C with 20–25% decomposition and about 50% weight loss was observed at 400°C.     

Synthesis and Properties of Mononuclear and Homobinuclear Chelates of Mn(II), Co(II), Ni(II), and Cu(II) with Phthalein Purple

Mono- and homobinuclear complexes of Mn(II), Co(II), Ni(II), and Cu(II) with phthalein purple are prepared and characterized by elemental analysis, thermal studies (TGA and DTA), spectral methods (IR, UV/Vis, and ESR), magnetic moment determination, and electrochemical reduction (DC polarography at DME and CV at HMDE). Thermal degradation of the complexes was studied by TGA and DTA where some thermodynamic parameters were determined. The mode of bonding and geometry of the complexes were determined from the spectral studies. Magnetic moment values showed some antiferromagnetism in the homobinuclear complexes. The reduction of the metal ions proceeds to the metallic state along an irreversible process.     

Self‐Assembly of a Giant Tetrahedral 3 d–4 f Single‐Molecule Magnet within a Polyoxometalate System

A giant tetrahedral heterometallic polyoxometalate (POM) [Dy₃₀Co₈Ge₁₂W₁₀₈O₄₀₈(OH)₄₂(OH₂)₃₀]^56?, which shows single‐molecule magnet (SMM) behavior, is described. This hybrid contains the largest number of 4f ions of any polyoxometalate (POM) reported to date and is the first to incorporate two different 3d–4f and 4f coordination cluster assemblies within same POM framework.     

Improved ion optics for introduction of ions into a 9.4‐T Fourier transform ion cyclotron resonance mass spectrometer

Enhancements to the ion source and transfer optics of our 9.4 T Fourier transform ion cyclotron resonance (ICR) mass spectrometer have resulted in improved ion transmission efficiency for more sensitive mass measurement of complex mixtures at the MS and MS/MS levels. The tube lens/skimmer has been replaced by a dual ion funnel and the following octopole by a quadrupole for reduced ion cloud radial expansion before transmission into a mass‐selective quadrupole. The number of ions that reach the ICR cell is increased by an order of magnitude for the funnel/quadrupole relative to the tube lens/skimmer/octopole. Copyright © 2015 John Wiley & Sons, Ltd.     

Product and Mechanism of Gas‐phase Pyrolysis of 2‐arylidinehydrazinopyrimidines: Interesting Route to Condensed Heterocycles[1]

Gas‐phase pyrolysis of N‐arylidine‐N′‐pyrimidin‐2‐yl‐hydrazine derivatives 1a , 1b , 1c , 1d , 1e gave the corresponding arylnitriles 2a , 2b , 2c , 2d , 2e , 2‐aminopyrimidine 3 , 3‐phenyl‐1,2,4‐triazolo[4,3‐a]pyrimidines 4 , 2‐phenyl‐1,2,4‐triazolo[1,5‐a]pyrimidines 5 , 2,4,5‐triphenyl‐1H‐imidazole 6 , and 2,3‐diphenylquinoline 7 . The analyses of the reaction products are reported and used to elucidate the mechanism of the pyrolytic process.     

Dynamic supported liquid membrane tip extraction of glyphosate and aminomethylphosphonic acid followed by capillary electrophoresis with contactless conductivity detection

A dynamic supported liquid membrane tip extraction (SLMTE) procedure for the effective extraction and preconcentration of glyphosate (GLYP) and its metabolite aminomethylphosphonic acid (AMPA) in water has been investigated. The SLMTE procedure was performed in a semi-automated dynamic mode and demonstrated a greater performance against a static extraction. Several important extraction parameters such as donor phase pH, cationic carrier concentration, type of membrane solvent, type of acceptor stripping phase, agitation and extraction time were comprehensively optimized. A solution of Aliquat-336, a cationic carrier, in dihexyl ether was selected as the supported liquid incorporated into the membrane phase. Quantification of GLYP and AMPA was carried out using capillary electrophoresis with contactless conductivity detection. An electrolyte solution consisting of 12 mM histidine (His), 8 mM 2-(N-morpholino)ethanesulfonic acid (MES), 75 μM cetyltrimethylammonium bromide (CTAB), 3% methanol, pH 6.3, was used as running buffer. Under the optimum extraction conditions, the method showed good linearity in the range of 0.01–200 μg/L (GLYP) and 0.1–400 μg/L (AMPA), acceptable reproducibility (RSD 5–7%, n = 5), low limits of detection of 0.005 μg/L for GLYP and 0.06 μg/L for AMPA, and satisfactory relative recoveries (90–94%). Due to the low cost, the SLMTE device was disposed after each run which additionally eliminated the possibility of carry-over between runs. The validated method was tested for the analysis of both analytes in spiked tap water and river water with good success.     

Rapid and direct determination of glyphosate,glufosinate, and aminophosphonic acid by online preconcentration CE with contactless conductivity detection

Rapid and direct online preconcentration followed by CE with capacitively coupled contactless conductivity detection (CE‐C⁴D) is evaluated as a new approach for the determination of glyphosate, glufosinate (GLUF), and aminophosphonic acid (AMPA) in drinking water. Two online preconcentration techniques, namely large volume sample stacking without polarity switching and field‐enhanced sample injection, coupled with CE‐C⁴D were successfully developed and optimized. Under optimized conditions, LODs in the range of 0.01–0.1 μM (1.7–11.1 μg/L) and sensitivity enhancements of 48‐ to 53‐fold were achieved with the large volume sample stacking‐CE‐C⁴D method. By performing the field‐enhanced sample injection‐CE‐C⁴D procedure, excellent LODs down to 0.0005–0.02 μM (0.1–2.2 μg/L) as well as sensitivity enhancements of up to 245‐ to 1002‐fold were obtained. Both techniques showed satisfactory reproducibility with RSDs of peak height of better than 10%. The newly established approaches were successfully applied to the analysis of glyphosate, glufosinate, and aminophosphonic acid in spiked tap drinking water.     

Reinforcement of natural rubber/high density polyethylene blends with electron beam irradiated liquid natural rubber-coated rice husk

Coating of rice husk (RH) surface with liquid natural rubber (LNR) and exposure to electron beam irradiation in air were studied. FTIR analysis on the LNR-coated RH (RHR) exposed to electron beam (EB) showed a decrease in the double bonds and an increase in hydroxyl and hydrogen bonded carbonyl groups arising from the chemical interaction between the active groups on RH surface with LNR. The scanning electron micrograph showed that the LNR formed a coating on the RH particles which transformed to a fine and clear fibrous layer at 20 kGy irradiation. The LNR film appeared as patches at 50 kGy irradiation due to degradation of rubber. Composites of natural rubber (NR)/high density polyethylene (HDPE)/RHR showed an optimum at 20–30 kGy dosage with the maximum stress, tensile modulus and impact strength of 6.5, 79 and 13.2 kJ/m², respectively. The interfacial interaction between the modified RH and TPNR matrix had improved on exposure of RHR to e-beam at 20–30 kGy dosage.     

A simple flow injection spectrophotometric determination method for iron(III) based on O-acetylsalicylhydroxamic acid complexation

A simple and rapid flow-injection spectrophotometric method for the determination of iron(III) and total iron is proposed. The method is based on the reaction between iron(III) and O-acetylsalicylhydroxamic acid (AcSHA) in a 2 % methanol solution resulting in an intense violet complex with strong absorption at 475 nm. Optimum conditions for the determination of iron(III) and the interfering ions were tested. The relative standard deviation for the determination of 5 μg L⁻¹ iron(III) was 0.85 % (n = 10), and the limit of detection (blank signal plus three times the standard deviation of the blank) was 0.5 μg L⁻¹, both based on the injection volumes of 20 μL. The method was successfully applied in the determination of iron(III) and total iron in water and ore samples. The method was verified by analysing a certified reference material Zn/Al/Cu 43XZ3F and also by the AAS method.     

Liquid Chromatographic Determination of NSAIDs in Urine After Dispersive Liquid–Liquid Microextraction Based on Solidification of Floating Organic Droplets

An environmentally benign method of sample preparation based on dispersive liquid–liquid microextraction and solidification of floating organic droplets (DLLME-SFO) coupled with high-performance liquid chromatography with ultraviolet detection has been developed for analysis of non-steroidal anti-inflammatory drugs (NSAIDs) in biological fluids. A low-toxicity solvent was used to replace the chlorinated solvents commonly used in conventional DLLME. Seven conditions were investigated and optimized: type and volume of extraction solvent and dispersive solvent, extraction time, effect of addition of salt, and sample pH. Under the optimum conditions, good linearity was obtained in the range 0.01–10 µg mL⁻¹, with coefficients of determination (r ²) >0.9949. Detection limits were in the range 0.0034–0.0052 µg mL⁻¹ with good reproducibility (RSD) and satisfactory inter-day and intra-day recovery (95.7–115.6 %). The method was successfully used for analysis of diclofenac, mefenamic acid, and ketoprofen in human urine. Analysis of urine samples from a patient 2 and 4 h after administration of diclofenac revealed concentrations of 1.20 and 0.34 µg mL⁻¹, respectively.