Controlled hydrogenation of diphenylacetylene using alkylammonium formate

A simple and straightforward semihydrogenation of alkyne to alkene with triethanolamine and formic acid in the presence of PdCl₂ has been described. Although hydrogenation using formic acid as a hydrogenation source has been used in combination with amines previously, few reports are available concerning the associated reactivity. We demonstrated that reactivity changes depending on the type of amine used in the hydrogenation. Further, this reaction requires no strict time control, making it a useful tool in organic synthesis.     

Surface modification of Cu metal particles by the chemical reaction between the surface oxide layer and a halogen surfactant

Surface oxides on small (2–5 μm) copper metal particles can be removed by chemical reaction with tris(2,3-dibromopropyl) isocyanurate (TIC) in diethylene glycol mono-n-hexyl ether (DGHE) solution under mild conditions where metal particles are not damaged. Surface oxides convert to copper bromide species and subsequently dissolve into the solvent. It was found that resultant surface species are resistant to re-oxidation due to remaining surface bromides. This finding opens up a possibility to create microclines based on cheap copper nanoparticles.     

Detailed kinetic analysis of the impact of nucleation behavior and particle size distribution on the configurations of carbon black

Journal of Nanoparticle Research - Dextrans are widely used as additives in food, pharmaceutical, and cosmetics because of their hydrophilicity, biocompatibility, and low toxicity. These features...     

149Sm and 57Fe nuclear resonant inelastic scattering of filled skutterudites SmFe4X12 (X: pnictogen)

¹⁴⁹Sm and ⁵⁷Fe nuclear resonant inelastic scattering (NRIS) measurements were carried out on SmFe₄P₁₂, SmFe₄As₁₂ and SmFe₄Sb₁₂. A clear dip structure of the ⁵⁷Fe NRIS spectrum was found in SmFe₄P₁₂, which was not clearly observed for SmFe₄As₁₂ and SmFe₄Sb₁₂. On the other hand, the line width of the phonon excitation in the ¹⁴⁹Sm NRIS spectrum increases with increasing the ionic radius of the pnictogen. These findings imply that the hybridization between the Sm and Fe phonon modes is correlated to changes in the ionic radius of the pnictogen.     

Synthesis of maltopentaose‐conjugated surface‐active styrenic monomers and their micellar homopolymerization in water

Maltopentaose (Mal₅)‐conjugated surface‐active styrenic monomers 1a , 1b , and 1c are described, which contain hydrophobic spacers, such as C1, C5, and C7 alkylene chains, respectively. The glycomonomers 1a‐c were synthesized by the direct β‐N‐glycosyl reaction of styrene derivatives with aminoalkyl groups 4a‐c onto Mal₅ in dry methanol, followed by the N‐acetylation with acetic anhydride. The self‐assembling properties for the aqueous solutions of 1a‐c were characterized by surface tension measurements and light scattering experiments, providing the physicochemical parameters for the formed 1a‐c micelles including the critical micelle concentration, apparent hydrodynamic radius (R_h,app), and weight average aggregation number (N_agg). The transmission electron microscope observations revealed the most important result in this study that 1a produced loose spherical micelles with the number average diameter (d_n) of 26 nm, while both 1b and 1c formed worm‐like micelles with the polymerizable core and the Mal₅ shell, whose number average contour lengths (l_ns) were 130 nm and 68 nm, respectively. The radical homopolymerizations of 1a‐c in water provided a substantial result in this study that 1b and 1c , that is, the glycomonomers forming the worm‐like micelles, showed a very high homopolymerizability in water. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1671–1679     

Six New Phenylpropanoid Derivatives from Chemically Converted Extract of Alpinia galanga (L.) and Their Antiparasitic Activities

Chemical conversion of the extract of natural resources is a very attractive way to expand the chemical space to discover bioactive compounds. In order to search for new medicines to treat parasitic diseases that cause high morbidity and mortality in affected countries in the world, the ethyl acetate extract from the rhizome of Alpinia galanga (L.) has been chemically converted by epoxidation using dioxirane generated in situ. The biological activity of chemically converted extract (CCE) of A. galanga (L.) significantly increased the activity against Leishmania major up to 82.6 ± 6.2 % at 25 μg/mL (whereas 2.7 ± 0.8% for the original extract). By bioassay-guided fractionation, new phenylpropanoids (1–6) and four known compounds, hydroquinone (7), 4-hydroxy(4-hydroxyphenyl)methoxy)benzaldehyde (8), isocoumarin cis 4-hydroxymelein (9), and (2S,3S,6R,7R,9S,10S)-humulene triepoxide (10) were isolated from CCE. The structures of isolated compounds were determined by spectroscopic analyses of 1D and 2D NMR, IR, and MS spectra. The most active compound was hydroquinone (7) with IC₅₀ = 0.37 ± 1.37 μg/mL as a substantial active principle of CCE. In addition, the new phenylpropanoid 2 (IC₅₀ = 27.8 ± 0.34 μg/mL) also showed significant activity against L. major compared to the positive control miltefosine (IC₅₀ = 7.47 ± 0.3 μg/mL). The activities of the isolated compounds were also evaluated against Plasmodium falciparum, Trypanosoma brucei gambisense and Trypanosoma brucei rhodeisense. Interestingly, compound 2 was selectively active against trypanosomes with potent activity. To the best of our knowledge, this is the first report on the bioactive “unnatural” natural products from the crude extract of A. galanga (L.) by chemical conversion and on its activities against causal pathogens of leishmaniasis, trypanosomiasis, and malaria.     

Excited‐State Dynamic Planarization of Cyclic Oligothiophenes in the Vicinity of a Ring‐to‐Linear Excitonic Behavioral Turning Point

Excited‐state dynamic planarization processes play a crucial role in determining exciton size in cyclic systems, as reported for π‐conjugated linear oligomers. Herein, we report time‐resolved fluorescence spectra and molecular dynamics simulations of π‐conjugated cyclic oligothiophenes in which the number of subunits was chosen to show the size‐dependent dynamic planarization in the vicinity of a ring‐to‐linear behavioral turning point. Analyses on the evolution of the total fluorescence intensity and the ratio between 0–1 to 0–0 vibronic bands suggest that excitons formed in a cyclic oligothiophene composed of six subunits fully delocalize over the cyclic carbon backbone, whereas those formed in larger systems fail to achieve complete delocalization. With the aid of molecular dynamics simulations, it is shown that distorted structures unfavorable for efficient exciton delocalization are more easily populated as the size of the cyclic system increases.