An efficient synthesis of nitroalkenes by alkene cross metathesis: facile access to small ring systems

A synthesis of highly functionalized nitroalkenes is reported that utilizes a cross metathesis (CM) reaction between simple aliphatic nitro compounds and a range of substituted alkenes. This chemistry offers a simple and attractive route to nitroalkenes that would otherwise be difficult to prepare, and that have a very useful application as precursors to a variety of heterocyclic entities.     

Rotational spectroscopy of the isotopic species of silicon monosulfide, SiS

Pure rotational transitions of silicon monosulfide ((28)Si(32)S) and its rare isotopic species have been observed in their ground as well as vibrationally excited states by employing Fourier transform microwave (FTMW) spectroscopy of a supersonic molecular beam at centimetre wavelengths (13-37 GHz) and by using long-path absorption spectroscopy at millimetre and submillimetre wavelengths (127-925 GHz). The latter measurements include 91 transition frequencies for (28)Si(32)S, (28)Si(33)S, (28)Si(34)S, (29)Si(32)S and (30)Si(32)S in upsilon = 0, as well as 5 lines for (28)Si(32)S in upsilon = 1, with rotational quantum numbers J'< or = 52. The centimetre-wave measurements include more than 300 newly recorded lines. Together with previous data they result in almost 600 transitions (J' = 0 and 1) from all twelve possible isotopic species, including (29)Si(36)S and (30)Si(36)S, which have fractional abundances of about 7 x 10(-6) and 4.5 x 10(-6), respectively. Rotational transitions were observed from upsilon = 0 for the least abundant isotopic species to as high as upsilon = 51 for the main species. Owing to the high spectral resolution of the FTMW spectrometer, hyperfine structure from the nuclear electric quadrupole moment of (33)S was resolved for species containing this isotope, as was much smaller nuclear spin-rotation splitting for isotopic species involving (29)Si. By combining the measurements here with previously published microwave and infrared data in one global fit, an improved set of spectroscopic parameters for SiS has been derived which include several terms describing the breakdown of the Born-Oppenheimer approximation. With this parameter set, highly accurate rotational frequencies for this important astronomical molecule can now be predicted well into the terahertz region.     

Laboratory detection of the elusive HSCO+ isomer

The rotational spectrum of protonated carbonyl sulfide, HSCO(+), has now been detected in the centimeter-wave band in a molecular beam by Fourier transform microwave spectroscopy. Rotational and centrifugal distortion constants have been determined from transitions in the K(a)=0 ladder of the normal isotopic species, and DSCO(+) and H(34)SCO(+). HSCO(+) is systematically more abundant by a factor of three than HOCS(+), the isomer obtained by attaching the H(+) to the other end of the molecule, which ab initio calculations long predicted to be higher in energy by 4-5 kcalmol. Because HSCO(+) is comparable in polarity to HOCS(+) and is apparently more stable and because OCS is widely distributed in astronomical sources, HSCO(+) is a good candidate for detection with radio telescopes.     

Rotational spectra of the van der Waals complexes of molecular hydrogen and OCS

The a- and b-type rotational transitions of the weakly bound complexes formed by molecular hydrogen and OCS, para-H2-OCS, ortho-H2-OCS, HD-OCS, para-D2-OCS, and ortho-D2-OCS, have been measured by Fourier transform microwave spectroscopy. All five species have ground rotational states with total rotational angular momentum J=0, regardless of whether the hydrogen rotational angular momentum is j=0 as in para-H2, ortho-D2, and HD or j=1 as in ortho-H2 and para-D2. This indicates quenching of the hydrogen angular momentum for the ortho-H2 and para-D2 species by the anisotropy of the intermolecular potential. The ground states of these complexes are slightly asymmetric prolate tops, with the hydrogen center of mass located on the side of the OCS, giving a planar T-shaped molecular geometry. The hydrogen spatial distribution is spherical in the three j=0 species, while it is bilobal and oriented nearly parallel to the OCS in the ground state of the two j=1 species. The j=1 species show strong Coriolis coupling with unobserved low-lying excited states. The abundance of para-H2-OCS relative to ortho-H2-OCS increases exponentially with decreasing normal H2 component in H2He gas mixtures, making the observation of para-H2-OCS in the presence of the more strongly bound ortho-H2-OCS dependent on using lower concentrations of H2. The determined rotational constants are A=22 401.889(4) MHz, B=5993.774(2) MHz, and C=4602.038(2) MHz for para-H2-OCS; A=22 942.218(6) MHz, B=5675.156(7) MHz, and C=4542.960(7) MHz for ortho-H2-OCS; A=15 970.010(3) MHz, B=5847.595(1) MHz, and C=4177.699(1) MHz for HD-OCS; A=12 829.2875(9) MHz, B=5671.3573(7) MHz, and C=3846.7041(6) MHz for ortho-D2-OCS; and A=13 046.800(3) MHz, B=5454.612(2) MHz, and C=3834.590(2) MHz for para-D2-OCS.     

Versatile multilayer thin film preparation using hydrophobic interactions, crystallization, and chemical modification of poly(vinyl alcohol)

Multilayer thin film coatings were prepared on silicon substrates. Poly(vinyl alcohol) was adsorbed from aqueous solution to propyldimethylsilyl-modified silicon wafers. This thin semicrystalline coating was chemically modified using acid chlorides to form thicker, hydrophobic coatings. The products of the modification reactions allowed adsorption of a subsequent layer of poly(vinyl alcohol) that could subsequently be hydrophobized. This two-step process (adsorption/chemical modification) allows layer-by-layer deposition to prepare coatings with thickness, chemical structure, and wettability control.     

Dibenzofuran Derivatives Inspired from Cercosporamide as Dual Inhibitors of Pim and CLK1 Kinases

Pim kinases (proviral integration site for Moloney murine leukemia virus kinases) are overexpressed in various types of hematological malignancies and solid carcinomas, and promote cell proliferation and survival. Thus, Pim kinases are validated as targets for antitumor therapy. In this context, our combined efforts in natural product-inspired library generation and screening furnished very promising dibenzo[b,d]furan derivatives derived from cercosporamide. Among them, lead compound 44 was highlighted as a potent Pim-1/2 kinases inhibitor with an additional nanomolar IC₅₀ value against CLK1 (cdc2-like kinases 1) and displayed a low micromolar anticancer potency towards the MV4-11 (AML) cell line, expressing high endogenous levels of Pim-1/2 kinases. The design, synthesis, structure–activity relationship, and docking studies are reported herein and supported by enzyme, cellular assays, and Galleria mellonella larvae testing for acute toxicity.     

Condensation on ultrahydrophobic surfaces and its effect on droplet mobility: ultrahydrophobic surfaces are not always water repellant

The condensation of water was studied on topography-based ultrahydrophobic surfaces containing hydrophobized silicon pillars. Optical microscopy showed that water nucleated and grew both on top of and between the pillars. As condensation progressed, water between the pillars became unstable and was forced upward to the surface. Macroscopic water droplets on top of the pillars coalesced with condensed water that remained between the pillars, pinning the droplets at their three-phase contact line. Dynamic contact angle measurements on ultrahydrophobic surfaces wet with condensation revealed a dramatic increase in hysteresis compared to that on dry surfaces, leading to a corresponding decrease in water drop mobility.     

Nylon surface modification: 2. Nylon-supported composite films

We have developed techniques for the introduction of reactive functional groups to nylon surfaces via site-specific reactions targeting at the naturally abundant amide repeating units on the surface. In this report, we describe the fabrication of nylon-supported composite surfaces using the most efficient modification methods we have developed. N-Alkylation with (3-glycidoxypropyl)triethoxysilane (GPTES) in the presence of potassium tert-butoxide (t-BuOK) leads to surfaces with silica-like reactivity. Subsequent chemical vapor deposition using tetrachlorosilane (SiCl4) and water results in composite films with a thin layer of silica, which was made hydrophobic by reaction with a fluorinated silane reagent. Reduction of the amide groups with borane-THF (BH3-THF) complex leads to a 69% conversion of surface amides to the corresponding secondary amine groups. Alginate was chosen as the model polyelectrolyte for the introduction of a hydrated surface layer. Because of the strong electrostatic interaction between alginate and the amine-enriched nylon surfaces, the adsorption is fast and concentration-independent (within the concentration range studied). The polysaccharide coats the surface homogeneously, without the formation of large aggregates. The amine surfaces obtained by reduction with BH3-THF ((BH3-THF)nylon-NH) and by alkylation with 2-bromoethylamine hydrobromide (BEA-HBr, (EBA-HBr)nylon-NH2) were also used to study gold deposition through electroless plating. Immobilization of a negatively charged metal complex (AuCl4(-)) was achieved through electrostatic interaction. Gold particles disperse preferentially in the bulk of (EBA-HBr)nylon-NH2 films, while they remain confined to the outer surface layer of (BH3-THF)nylon-NH films.     

From Waste to Green Applications: The Use of Recovered Gold and Palladium in Catalysis

The direct use in catalysis of precious metal recovery products from industrial and consumer waste is a very promising recent area of investigation. It represents a more sustainable, environmentally benign, and profitable way of managing the low abundance of precious metals, as well as encouraging new ways of exploiting their catalytic properties. This review demonstrates the feasibility and sustainability of this innovative approach, inspired by circular economy models, and aims to stimulate further research and industrial processes based on the valorisation of secondary resources of these raw materials. The overview of the use of recovered gold and palladium in catalytic processes will be complemented by critical appraisal of the recovery and reuse approaches that have been proposed.     

Broad‐Band Time‐Resolved Near Infrared Spectroscopy in the TJ‐II Stellarator

First experimental results on broad‐band, time‐resolved Near Infrared (NIR;here loosely defined as covering from 750 to 1650 nm) passive spectroscopy using a high sensitivity InGaAs detector are reported for the TJ‐II Stellarator. Experimental set‐up is described together with its main characteristics, the most remarkable ones being its enhanced NIR response, broadband spectrum acquisition in a single shot, and time‐resolved measurements with up to 1.8 kHz spectral rate. Prospects for future work and more extended physics studies in this newly open spectral region in TJ‐II are discussed. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)