Diterpenoid Alkaloids of Delphinium buschianum Grossh.

From the aerial parts of Delphinium buschianum Grossh ., collected in Turkey, a new diterpenoid alkaloid 1 , named budelphine, was isolated along with the known diterpenoid alkaloids karakoline ( 2 ), 18‐hydroxy‐14‐O‐methylgadesine ( 3 ), delsoline ( 4 ), lapaconidine ( 5 ), columbianine ( 6 ), 14‐benzoylneoline ( 7 ), and hetisine ( 9 ). The structure of 1 was established on the basis of ¹H‐, ¹³C‐, DEPT, ¹H,¹H‐COSY, NOESY, HSQC, and HMBC NMR studies.     

New functional chiral P-based ligands and application in ruthenium-catalyzed enantioselective transfer hydrogenation of ketones

Metal-catalyzed asymmetric transfer hydrogenation is a powerful and practical method for the reduction of ketones to produce the corresponding secondary alcohols, which are valuable building blocks in the pharmaceutical, perfume, and agrochemical industries. Hence, a series of novel chiral β-amino alcohols were synthesized by chiral amines with regioselective ring opening of (S)-propylene oxide or reaction with (S)-(+)-2-hydroxypropyl p-toluenesulfonate by a straightforward method. The chiral ruthenium catalytic systems generated from [Ru(arene)(μ-Cl)Cl]₂ complexes and chiral phosphinite ligands based on amino alcohol derivatives were employed in asymmetric transfer hydrogenation of ketones to give the corresponding optically active alcohols; (2S)-1-{[(2S)-2-[(diphenylphosphanyl)oxy]propyl][(1R)-1-phenylethyl]amino}propan-2-yldiphenylphosphinitobis[dichol-oro(η⁶-benzene)ruthenium(II)] acts an excellent catalyst in the reduction of α-naphthyl methyl ketone, giving the corresponding alcohol with up to 99% ee. The substituents on the backbone of the ligands were found to have a remarkable effect on both the conversion and enantioselectivity of the catalysts. Furthermore, this transfer hydrogenation is characterized by low reversibility under these conditions.     

New chiral ruthenium(II)–phosphinite complexes containing a ferrocenyl group in enantioselective transfer hydrogenations of aromatic ketones

A new and versatile class of unsymmetrical ferrocenyl-phosphinite ligands possessing a stereogenic center has been prepared from commercially available, inexpensive aminoacids such as, d-, l-phenylglycine and d-, l-phenylalanine, through a concise synthetic procedure. These ligands are not very sensitive to air and moisture, and display good enantioselectivities in the ruthenium-catalyzed asymmetric transfer hydrogenation of acetophenone derivatives, in which up to 91% ee was obtained. A comparison of the catalytic properties of amino alcohols and other analogues based on a ferrocenyl backbone is also discussed briefly. The structures of these ligands and their corresponding complexes have been elucidated by a combination of multinuclear NMR spectroscopy, IR spectroscopy, and elemental analysis.     

Dose response of hydrazine – Deproteinated tooth enamel under blue light stimulation

The beta dose response and Optically Stimulated Luminescence (OSL) signal stability characteristics of human tooth enamel deproteinated by hydrazine reagent under blue photon stimulation are reported. Removal of the protein organic component of tooth enamel resulted in a higher OSL sensitivity and slower fading of OSL signals. The effect of chemical sample preparation on the enamel sample sensitivity is discussed and further steps to make this deproteinization treatment suitable for in vitro dose reconstruction studies are suggested.     

Asymmetric cellulose nanocrystals: thiolation of reducing end groups via NHS–EDC coupling

Cellulose nanocrystals (CNC) were functionalized in aqueous media at the reducing, aldehyde ends of cellulose. CNC oxidation to produce carboxyl groups was followed by carbodiimide-mediated reaction to install thiol groups. The selectivity and extent of thiolation at the reducing ends was qualitatively confirmed by imaging (transmission electron microscopy) silver nanoparticles that tagged the CNC termini and by X-ray photoelectron spectroscopy, respectively. The adsorption of thiolated CNC onto gold surfaces as well as the viscoelastic property of the formed adlayer was investigated by using quartz crystal microgravimetry. The thiolated CNC chemisorbed on the surfaces were further analyzed for surface density and distribution by using atomic force microscopy. Overall we introduce a facile, mild asymmetric thiolation procedure as an efficient alternative to conventional reductive amination.     

Deformational Properties of Irradiated Composite Materials Based on PET and PE

Considering the wide applicability of polymeric composite materials, heterogeneous blends of poly(ethylene terephtalate) (PET) and polyethylenes of high and low densities (HDPE and LDPE, respectively) were investigated. Rheological (the flow-behavior index), mechanical (the yield strength and the Charpy impact strength), and morphological (crystallinity and the melting temperature) properties were detected for individual blend components and different blend compositions. A radiation treatment (-rays) was applied to improve certain characteristics of the heterogeneous blends. The results of this investigation show that the radiation modification can be successfully used to improve some physical properties of the PET-based blends and to choose individual blend components, optimum irradiation conditions, and desirable blend compositions, which allows producing materials with a predictable set of mechanical properties.     

Determination of ergot alkaloids from grains with UPLC‐MS/MS

A simple and rapid method for determining six ergot alkaloids and four of their respective epimers was developed for rye and wheat. The analytes were extracted from the sample matrix with ACN/ammonium carbonate solution. The extract was purified with a commercial push‐through SPE column (Mycosep^® 150 Ergot). After concentration and filtration steps, the final separation of the analytes was achieved with ultra‐performance LC‐MS/MS. The chromatographic separation of the ergot alkaloids was achieved in 4.5 min. The method performance proved satisfactory in the preliminary validation. The calculated LOQs were low ranging from 0.01 to 1.0 μg/kg for wheat and from 0.01 to 10.0 μg/kg for rye. At the concentration levels of 10, 50 and 200 μg/kg, the recoveries were between 80 and 120% in most cases and the within‐day repeatability (expressed as RSD) ranged between 1.3 and 13.9%. Despite the cleanup of the samples, some matrix effect was observed in the MS, highlighting the necessity of using matrix‐assisted standards. This is the first article to describe the application of the push‐through columns and ultra‐performance LC in the analysis of ergot alkaloids.     

An approach for obtaining the intensity of the radiation transmitted through a scatterer

Monte Carlo simulation was applied to the investigation of intensity of the radiation transmitted through a scatterer. Simulations consisted of a pencil beam of monoenergetic photons with energies from 50 keV to 10 meV incident on water, aluminium, iron, copper, tin and lead slabs. We determined the scattered radiation and the scatter fractions recorded in the detector plane. An empirical formula, which is a function of the physical parameters scatterer thickness, the linear attenuation coefficient, and the atomic number was obtained for intensity of radiation transmitted through a scatterer. This work was supported by the Scientific and Technical Research Council of Turkey (TUBITAK) [TBAG-2032 (101T053)].     

Thermal analysis: an effective characterization method of polyvinyl acetate films applied in corrosion inhibition field

Journal of Thermal Analysis and Calorimetry - To prepare a commercial product with economic and technical relevance, polyvinyl acetate (PVAc) was synthesized, under our laboratory conditions,...     

Biological assays and theoretical density functional theory calculations of Rh(I), Ir(III), and Ru(II) complexes of chiral phosphinite ligand

Four metal complexes, IL-OPPh₂-Ru-p-cymene (3) , IL-OPPh₂-Ru-benzene (4) , IL-OPPh₂-Ir-Cp* (5) , IL-OPPh₂-Rh-COD (6) , have been evaluated for in vitro antioxidant activity such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and reducing power activity. Maximum scavenging activity (71.43%) was obtained with IL-OPPh₂-Ru-p-cymene, whereas IL-OPPh₂-Rh-COD showed the highest reducing power ability. The complexes were also studied for their antimicrobial activity against three Gram-positive and three Gram-negative bacteria. In addition, DNA binding of the complexes was evaluated using calf thymus DNA. Both Ru(II) complexes exhibited good DNA-binding activity while the other complexes did not have any activity. Furthermore, ab initio quantum calculations of four complexes were also carried out using density functional theory to better understand their chemical behaviors.