CLUSTER COMPLEXES OF RHENIUM WITH CARBONYL AND AMINE CONTAINING LIGANDS

Methods for the synthesis of rhenium cluster complexes based on carbonyl and amine containing organic bifunctional ligands have been developed. The structure of the obtained cluster combinations were determined on the basis of IR spectroscopy data, methods of thermogravimetry and elemental analysis. Samples of ligands I and II were obtained by condensation of cyclopentane and cyclohexane carboxylic acids chloroanhydrides with ethylene, followed by the replacement of the chlorine atom by amine groups. To obtain cluster complexes of rhenium with the synthesized ligands, an ultradisperse solution of rhenium in distilled water was prepared in advance. To this end, the rhenium trichloride salt (ReCl3) was dissolved in water and the calculated amount of sodium borohydride in a nitrogen atmosphere was added in portions to the resulting solution with vigorous stirring. Rapidly arising black dispersed nanoparticles of metallic rhenium were not deposited. When organic ligands I and II are added, the corresponding cluster compounds III and IV are formed, which gradually over 30 minutes. precipitated from aqueous solution. The resulting black-brown precipitates were washed with distilled water and dried in a nitrogen atmosphere at a temperature of 35-40 °C. The melting points of the synthesized compounds are determined, which are components for cluster III-195 °С and cluster IV- 212 °С (with decomposition). In the IR spectra of cluster compounds, intense absorption bands were found, which characterize the presence of both a ketone carbonyl group (1718 sm–1, 1720 sm–1) and an amine fragment (2727 sm–1, 2720 sm–1 and 2613 sm–1, 2609 sm–1). The absorption bands of ketone groups in cluster compounds are shifted toward higher frequencies compared to the initial ligands. A similar picture is observed when comparing IR vibrations of C – N bonds in the initial ligands and the corresponding cluster compounds. The results of elemental analysis confirm the structure of cluster compounds and are in complete agreement with the notion that the reduction of rhenium salts with metal hydrides in an aqueous solution forms cluster compounds. Apparently, in this case, the most stable rhenium clusters with a tetrahedral structure are formed. Thermogravimetric analysis made it possible to establish the presence of a peak at a temperature of 318 °С with a mass number of 744.8 c.u. corresponding to the cluster combination of four rhenium atoms. At each stage of decomposition, the experimental mass loss agrees well with the calculated values.

Synthesis of Fused Oxepane HIV Integrase Inhibitor MK-1376

Controlling the absolute and relative stereochemistry of a seven-membered oxepane in the formation of HIV integrase inhibitor MK-1376 was accomplished through a strategy involving the use of asymmetric allylation and stereoconvergent, substrate-directed installation of an amine fragment. Surprising reactivity was demonstrated during the asymmetric allylation in which the allyl-pyrimidone product was formed reversibly. The stereoconvergent amine addition was accomplished through an elimination/addition sequence involving a quinone methide reactive intermediate, and nucleophilic trapping of the reactive quinone methide intermediate with methylamine. This novel approach delivered MK-1376, offering 100-fold greater productivity and 50-fold less waste than the initial synthetic chemistry route.

The impacts of regional shipping emissions on the chemical characteristics of coastal submicron aerosols near Houston, TX

The air quality of the Texas Gulf Coast region historically has been influenced heavily by regional shipping emissions. However, the effects of the recently established North American Emissions Control Area on aerosol concentrations and properties in this region are presently unknown. In order to better understand the current sources and processing mechanisms influencing coastal aerosol near Houston, a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed for 3 weeks at a coastal location during May–June 2016. Total mass loadings of organic and inorganic non-refractory aerosol components during onshore flow periods were similar to those published before establishment of the regulations. Based on estimated methanesulfonic acid (MSA) mass loadings and published biogenic MSA / non-sea-salt sulfate (nss-SO4) ratios, an average of over 75 % of the observed nss-SO4 was from anthropogenic sources, predominantly shipping emissions. Mass spectral analysis indicated that for periods with similar backward-trajectory-averaged meteorological conditions, air masses influenced by shipping emissions had an increased mass fraction of ions related to carboxylic acids and larger oxygen-to-carbon ratios than those that avoided shipping lanes, suggesting that shipping emissions increase marine organic aerosol (OA) oxidation state. Amine fragment mass loadings were correlated positively with anthropogenic nss-SO4 during onshore flow, implying anthropogenic–biogenic interaction in marine OA production. Model calculations also suggest that advection of shipping-derived aerosol may enhance inland aqueous-phase secondary OA production. These results imply a continuing role of shipping emissions on aerosol properties over the Gulf of Mexico and suggest that further regulation of shipping fuel sulfur content will reduce coastal submicron aerosol mass loadings near Houston.

The impacts of regional shipping emissions on the chemical characteristics of coastal submicron aerosols near Houston, TX

The air quality of the Texas Gulf Coast region historically has been influenced heavily by regional shipping emissions. However, the effects of the recently established North American Emissions Control Area on aerosol concentrations and properties in this region are presently unknown. In order to better understand the current sources and processing mechanisms influencing coastal aerosol near Houston, a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed for three weeks at a coastal location during May–June 2016. Total mass loadings of organic and inorganic non-refractory aerosol components during onshore flow periods were similar to those published before establishment of the regulations. Based on estimated methanesulfonic acid (MSA) mass loadings and published biogenic MSA to non-sea-salt-sulfate (nss-SO4) ratios, an average of over 75 % of the observed nss-SO4 was from anthropogenic sources, predominantly shipping emissions. Mass spectral analysis indicated that for periods with similar backward-trajectory-averaged meteorological conditions, air masses influenced by shipping emissions had an increased mass fraction of ions related to carboxylic acids and larger oxygen-to-carbon ratios than those that avoided shipping lanes, suggesting that shipping emissions increase marine organic aerosol (OA) oxidation state. Amine fragment mass loadings were correlated positively with anthropogenic nss-SO4 during onshore flow, implying anthropogenic-biogenic interaction in marine OA production. Model calculations also suggest that advection of shipping-derived aerosol may enhance inland aqueous-phase secondary OA production. These results emphasize the continuing role of shipping emissions on aerosol properties over the Gulf of Mexico and suggest that further regulation of shipping fuel sulfur content will reduce coastal submicron aerosol mass loadings near Houston.

In vitro and in vivo antiproliferative activity of organo-nickel SCS-pincer complexes on estrogen responsive MCF7 and MC4L2 breast cancer cells. Effects of amine fragment substitutions on BSA binding and cytotoxicity

A family of organonickel complexes has been prepared, fully characterized, and tested for their antiproliferative activity against estrogen-responsive human breast cancer cells (MCF7).

Effect of azodicarbonamide on microstructure, cure kinetics and physical properties of natural rubber foam

The effect of azodicarbonamide as chemical blowing agent on the morphology, cure kinetics and physical properties of natural rubber foam is investigated. From the morphology, when the amount of chemical blowing agent increases from 3 to 4 phr, the bubble size in the rubber matrix slightly decreases due to the increase of vulcanization reaction rate from the presence of amine fragment species as by-products from the decomposition of azodicarbonamide. The coalescence between bubbles is observed in the specimen with 5 and 6 phr of azodicarbonamide owing to high gas content in the rubber matrix. Moreover, the scorch time slightly reduces and cure rate increases as a function of azodicarbonamide content. The autocatalytic model can be used to explain the curing reaction and mechanism of this natural rubber foam. Furthermore, the activation energy (Ea) directly relates to the bubble size and microvoid structure of natural rubber foam. When compared with the vulcanized natural rubber without adding chemical blowing agent, it is found that the bulk density of natural rubber foam significantly decreases and the volumetric expansion ratio of natural rubber foam increases at high content of chemical blowing agent. Moreover, natural rubber foam at 4 phr of azodicarbonamide exhibits the lowest thermal expansion coefficient due to the smallest bubble size with less coalescence.

Crystal structure ofN,N-dimethyl-2-[(4-methylbenzyl)sulfonyl]ethanamine

In the crystal, the title compound, C12H19NO2S, has a disordered structure with two equally populated conformations of the amine fragment. A pair of weak C—H...O intermolecular interactions between the CH2and SO2groups gives a one-dimensional supramolecular structure that propagates through translation along thea-axis direction.