Magnetic hollow poly(N-isopropylacrylamide-co-N,N′-methylenebisacrylamide-co-glycidyl acrylate) particles prepared by inverse emulsion polymerization

To prepare functionalized magnetic polymer particles that are thermally responsive, inverse emulsion copolymerization of N-isopropylacrylamide, N,N′-methylenebisacrylamide and glycidyl acrylate (GA) was investigated in paraffin oil in the presence of γ-Fe₂O₃ nanoparticles dispersed in a water/glycerol mixture. The resulting polymer particles were characterized regarding the morphology, size, polydispersity, iron content, and the temperature-dependent phase transition using optical microscopy, transmission electron microscopy, scanning electron microscopy, atomic absorption spectroscopy, and differential scanning calorimetry. Magnetic properties were examined using hysteresis loop measurements and by analyzing the magnetic susceptibility with respect to temperature. We have also investigated the influence of the concentration of γ-Fe₂O₃ and GA in monomers on properties of the particles (morphology, size, and presence of oxirane groups). The particles possessed a hollow structure as a result of phase separation between water/glycerol hydrophilic solvents in the polymerization feed and the forming polymer. Depending on the concentration of γ-Fe₂O₃ in the monomer phase, the magnetic hollow particles contained 5–24 wt% iron. In water, the particles gradually collapsed when the temperature was raised to 40 °C because the elevated temperature weakened hydration and the PNIPAAm chains gradually became more hydrophobic.     

Palladium-catalysed Claisen rearrangement of 6-allyloxypurines

6-Allyloxypurines readily undergo palladium-catalysed Claisen rearrangement under mild conditions affording N ¹-substituted hypoxanthines. In contrast with the previously reported protocol, the Claisen rearrangement can be performed using Pd(PPh₃)₄ or Pd(dba)₂/dppf in dry THF at 60°C. The reaction can accommodate variously substituted allyl fragments to position N ¹ of the hypoxanthine skeleton with high yields. Retention of the double bond configuration during rearrangement was observed.     

Study of the retention behavior of small polar molecules on different types of stationary phases used in hydrophilic interaction liquid chromatography

The retention behavior of a large group of analytes (35) with varied properties (pK_a and logP) was studied on eight hydrophilic interaction LC columns with different surfaces, stationary phase chemistries, and types of particles. The acetonitrile content (5–95%), buffer concentration (0.5–200 mM), and pH of the mobile phase (3.8 and 6.8) were evaluated for their effects on the retention behavior. The type of stationary phase had a significant impact on the selectivity and retention time of the tested analytes. Completely different selectivity was observed on the aminopropyl stationary phase. In this study, the influence of the buffer concentration was similar for all tested columns, except for the aminopropyl stationary phase. Increasing the buffer concentration led to decreased retention times for the basic compounds and increased retention times for the acidic compounds, while the inverse behavior was observed on the aminopropyl stationary phase. The selectivity of the individual stationary phases was evaluated at pH 3.8 and 6.8. Much lower selectivity differences between the stationary phases were observed at pH 6.8 than pH 3.8. Bare silica stationary phases were used in the comparison of the particles (fused‐core and fully porous particles of 3 and 1.7 μm) and the columns provided by different manufacturers.     

Timing performance of ZnO:Ga nanopowder composite scintillators

The implementation of nanocrystal‐based composite scintillators as a new generation of ultrafast particle detectors is explored using ZnO:Ga nanopowder. Samples are characterized with a spectral‐time resolved photon counting system and pulsed X‐rays, followed by coincidence time resolution (CTR) measurements under 511 keV gamma excitation. Results are comparable to CTR values obtained using bulk inorganic scintillators. Bringing the ZnO:Ga nanocrystal's timing performance to radiation detectors could pave the research path towards sub‐20 ps time resolution as shown in this contribution. However, an efficiency boost when placing nanopowders in a transparent host constitutes the main challenge in order to benefit from sub‐nanosecond recombination times. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Synthesis and antioxidant assay of new nicotinonitrile analogues clubbed thiazole,pyrazole and/or pyridine ring systems

A series of novel nicotinonitrile derivatives were synthesized by hybridization with thiazole, pyrazole, and pyridine ring systems using 4-aminobenzohydrazide as link-bridge. The synthetic strategy of nicotinonitrile-thiazole analogues involves cyclization of the precursor N-phenyl thiosemicarbazide derivative 4 with chloroacetic acid and phenacyl bromide. The reaction of hydrazide 3 with acetylacetone and/or ethyl acetoacetate was applied as a synthetic route for accessing 2-((4-(pyrazole-1-carbonyl)phenyl)amino)-nicotinonitrile derivatives 9–10 . The 2-((4-(4-thiazolylidene-pyrazole-1-carbonyl)-phenyl)amino)nicotinonitriles 14–15 were obtained via a nucleophilic addition of pyrazolone 10 to phenyl isothiocyanate followed by cyclization with chloroacetone, phenacyl chloride, and/or ethyl bromoacetate. The 6-amino-4-aryl-3,5-dicyano-2-oxo-1-(4-substitutedbenzamido)-pyridines 19 were synthesized by Knoevenagel condensation N′-(2-cyanoacetyl)-benzohydrazide derivative 16 with substituted benzaldehydes followed by heating with malononitrile. All synthesized products were evaluated for their antioxidant potentialities using of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical cation delcolorization assay. The nicotinonitrile-thiazole hybrid 6b was found the most promising antioxidant agent with inhibition activity 86.27%.     

Ni(II)-Schiff base/SBA-15: a nanostructure and reusable catalyst for one-pot three-component green synthesis of 3,4-dihydropyrano[3,2-c]chromene derivatives

Research on Chemical Intermediates - An efficient, rapid, and environmentally benign Ni(II)-Schiff base/SBA-15-catalyzed one-pot three-component cyclocondensation process was described via the...     

Glycoconjugated Metallohelices have Improved Nuclear Delivery and Suppress Tumour Growth In Vivo

Monosaccharides are added to the hydrophilic face of a self‐assembled asymmetric Fe^II metallohelix, using CuAAC chemistry. The sixteen resulting architectures are water‐stable and optically pure, and exhibit improved antiproliferative selectivity against colon cancer cells (HCT116 p53^+/+) with respect to the non‐cancerous ARPE‐19 cell line. While the most selective compound is a glucose‐appended enantiomer, its cellular entry is not mainly glucose transporter‐mediated. Glucose conjugation nevertheless increases nuclear delivery ca 2.5‐fold, and a non‐destructive interaction with DNA is indicated. Addition of the glucose units affects the binding orientation of the metallohelix to naked DNA, but does not substantially alter the overall affinity. In a mouse model, the glucose conjugated compound was far better tolerated, and tumour growth delays for the parent compound (2.6 d) were improved to 4.3 d; performance as good as cisplatin but with the advantage of no weight loss in the subjects.     

Fast simultaneous LC/MS/MS determination of 10 active compounds in human serum for therapeutic drug monitoring in psychiatric medication

A UPLC/MS/MS method with simple protein precipitation has been validated for the fast simultaneous analysis of agomelatine, asenapine, amisulpride, iloperidone, zotepine, melperone, ziprasidone, vilazodone, aripiprazole and its metabolite dehydro‐aripiprazole in human serum. Alprenolol was applied as an internal standard. A BEH C₁₈ (2.1 × 50 mm, 1.7 µm) column provided chromatographic separation of analytes using a binary mobile phase gradient (A, 2 mmol/L ammonium acetate, 0.1% formic acid in 5% acetonitrile, v/v/v; B, 2 mmol/L ammonium acetate, 0.1% formic acid in 95% acetonitrile, v/v/v). Mass spectrometric detection was performed in the positive electrospray ionization mode and ion suppression owing to matrix effects was evaluated. The validation criteria were determined: linearity, precision, accuracy, recovery, limit of detection, limit of quantification, reproducibility and matrix effect. The concentration range was as follows: 0.25–1000 ng/mL for agomelatine; 0.25–100 ng/mL for asenapine and iloperidone; 2.5–1000 ng/mL for amisulpride, aripiprazole, vilazodone and zotepine; 2.3–924.6 ng/mL for dehydroaripiprazole; 2.2–878.4 ng/mL for melperone; and 2.2–883.5 ng/mL for ziprasidone. Limits of quantitation below a therapeutic reference range were achieved for all analytes. Intra‐run precision of 0.4–5.5 %, inter‐run precision of 0.6–8.2% and overall recovery of 87.9–114.1% were obtained. The validated method was successfully implemented into routine practice for therapeutic drug monitoring in our hospital. Copyright © 2015 John Wiley & Sons, Ltd.