Convenient synthesis of heteroaryl-linked benzimidazoles via microwave-assisted boronate ester formation

N-Substituted 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-benzimidazoles were conveniently accessed via microwave-assisted synthesis. Subsequent Suzuki-Miyaura cross-coupling with heteroaryl halides proceeded to give a wide variety of heteroaryl-substituted benzimidazoles.     

A palladium-catalyzed regio- and stereoselective four-component coupling reaction

Pd(PPh(3))(4) catalytically assembles sulfenamide, alkyne, carbon monoxide, and diphenyl diselenide regio- and stereoselectively in a one-pot four-component coupling reaction to yield (Z)-beta-selenyl acrylamides. The reaction proceeds in good to excellent yields (60-95%) and is tolerant of a range of functional groups on both the nitrogen of the sulfenamide and the alkyne. Moderate selectivities ranging from 4:1 to 7:1 beta-selenyl to beta-sulfenyl acrylamide have been observed despite the initial concentration of 2:1 selenium to sulfur in the reaction. The chalcogeno selectivity was found to depend directly on CO pressure; increased pressure decreased selectivity for selenium over sulfur.     

The regio- and stereoselective one-pot catalytic preparation of beta-selenyl acrylamides

Pd(PPh(3))(4) is found to catalytically assemble sulfenamides, terminal aliphatic alkynes, carbon monoxide, and diphenyl diselenides regio- and stereoselectively in a single-pot reaction to produce good yields of beta-selenyl acrylamides. [reaction: see text]     

Analysis of thin films and molecular orientation using cluster SIMS

A study of phenylalanine films of different thicknesses from submonolayer to 55 nm on Si wafers has been made using Bi_n⁺ and C₆₀⁺ cluster primary ions in static SIMS. This shows that the effect of film thickness on ion yield is very similar for all primary ions, with an enhanced molecular yield at approximately 1 monolayer attributed to substrate backscattering. The static SIMS ion yields of phenylalanine at different thicknesses are, in principle, the equivalent of a static SIMS depth profile, without the complication of ion beam damage and roughness resulting from sputtering to the relevant thickness. Analyzing thin films of phenylalanine of different thicknesses allows an interpretation of molecular bonding to, and orientation on, the silicon substrate that is confirmed by XPS. The large crater size for cluster ions has interesting effects on the secondary ion intensities of both the overlayer and the substrate for monolayer and submonolayer quantities. This study expands the capability of SIMS for identification of the chemical structure of molecules at surfaces. © Crown copyright 2010.     

Trace analysis of uranium ore concentrates using laser ablation inductively coupled plasma mass spectrometry for nuclear forensics

Journal of Radioanalytical and Nuclear Chemistry - We present a laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) method for trace-element analysis of uranium ore concentrates...     

Preparation and synthesis a new chemotherapeutic drug of silver nanoparticle-chitosan composite; Chemical characterization and analysis of their antioxidant,cytotoxicity, and anti-acute myeloid leukemia effects in comparison to Daunorubicin in a leukemic mouse model

Nanoparticles usually have better outcomes than the bulk samples of the same element because they possess a higher specificity level than the larger particles. This is also true for silver nanoparticles, and little amount of these materials has high remedial effects. Silver nanoparticles are used as a therapeutic tool for the treatment of several diseases such as cancer. In this study, silver nanoparticles using chitosan (AgNPs-chitosan composite) are reported for the first time to exert a dietary therapeutic potential compared to Daunorubicin in an animal model of acute myeloid leukemia. The synthesized AgNPs-chitosan composite was characterized using different techniques including ultraviolet–visible spectroscopy, fourier-transform infrared spectroscopy, energy dispersive X-ray spectrometry, scanning electron microscopy, and transmission electron microscopy. FTIR findings suggested antioxidant compounds in the nanoparticles were the sources of reducing power, reducing silver ions to AgNPs. SEM and TEM images exhibited a uniform spherical morphology and average diameters of 30 nm for the nanoparticles. Then, 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging test was done to evaluate the antioxidant potentials of Daunorubicin, AgNO₃, chitosan, and AgNPs-chitosan composite. DPPH test revealed similar antioxidant potentials for Daunorubicin and AgNPs-chitosan composite. For the analyzing of cytotoxicity effects of Daunorubicin, AgNO₃, chitosan, and AgNPs, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromidefor (MTT) assay was used on HUVEC, 32D-FLT3-ITD, and Murine C1498 cell lines. AgNPs-chitosan composite similar to Daunorubicin had low cell viability dose-dependently against 32D-FLT3-ITD and Murine C1498 cell lines without any cytotoxicity on HUVEC cell line. In vivo design, induction of acute myeloid leukemia was done by 7,12-Dimethylbenz[a]anthracene in 50 mice. Then, the animals were randomly divided into six subgroups, including control, untreated, Daunorubicin, AgNO₃, chitosan, and AgNPs-chitosan composite. Similar to Daunorubicin, AgNPs-chitosan composite significantly (P ≤ .01) decreased the weight of the body, the pro-inflammatory cytokines, and the total white blood cells, blast, neutrophil, monocyte, eosinophil, and basophil counts and increased the anti-inflammatory cytokines and the lymphocyte, platelet, and red blood cell parameters as compared to the untreated mice. These results show that the inclusion of chitosan improves the therapeutic properties of AgNPs-chitosan composite, which led to a significant enhancement in the antioxidant, cytotoxicity, and anti-acute myeloid leukemia activities of the nanoparticles. It appears that AgNPs-chitosan composite can be used as a chemotherapeutic drug for the treatment of acute myeloid leukemia in the clinical trial.