Synergistic solvent extraction of Eu(III) and Tb(III) with mixtures of various organophosphorus extractants

Synergistic solvent extraction of Eu(III) and Tb(III) from thiocyanate solutions with mixtures of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHPNA) and di-2-ethylhexylphosphoric acid (DEHPA) or tributyl phosphate (TBP) or trioctylphosphine oxide (TOPO) or triphenylphosphine oxide (TPhPO) in benzene has been studied. The mechanism of extraction can be explained by a simple chemically based model presented in this paper. The equilibrium constants of the mixed-ligand species of the various neutral donors have been determined by non-linear regression analysis.     

Synthesis and characterization of oxygen depleted tert-amine calix[4]arene ligands and study the effect on sigma non-opioid intracellular protein receptor

Structural Chemistry - This study focuses on the biological prospects of oxygen-depleted calix[4]arene ligands on a protein target. Because of their extensive medical relevance, the oxygen-depleted...     

Synthesis of supramolecular precision polymers: Crystallization under conformational constraints

Placing artificial folding elements into precision polymers is an important strategy to systematically study structure formation in self‐assembly, particularly in the semicrystalline state. To this purpose, a series of precision polymers bearing either a N‐ protected or N‐ unprotected diaminopyridine (DAP) unit after every 16th, 18th, and 20th carbon as well as a urea unit after every 20th carbon along a polyethylene‐like polymer were synthesized via acyclic diene metathesis polymerization and subsequent hydrogenation. The polymers thus contain either H‐bonds (urea/DAP), π–π‐elements (DAP), or no H‐bonds (respective N? protected urea/DAP‐units) in their main chain, able to consequently study the crystallization behavior under influence of such supramolecular moieties. Therefore, the thermal properties and crystallization behavior were analyzed via differential scanning calorimetry (DSC) as well as wide angle X‐ray diffraction. The obtained crystalline polymer is influenced by the different supramolecular interactions existing between adjacent polymer chains and the varying defect size exerted by the incorporated functional groups. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3736–3748     

Facile one pot multicomponent synthesis of novel 4-(benzofuran-2-yl)-2-(3-(aryl/heteryl)-5-(aryl/heteryl)-4,5-dihydro-1H-pyrazol-1yl)thiazole derivatives

An efficient base catalyzed one pot multicomponent reaction of aryl/hetryl chalcones, thiosemicarbazide and 1-(benzofuran-2-yl)-2-bromoethan-1-one was developed to synthesize the novel 4-(benzofuran-2-yl)-2-(3-(aryl/heteryl)-5-(aryl/heteryl)-4,5-dihydro-1H-pyrazol-1yl)thiazole derivatives.     

Synthesis of Novel Drug‐Like Small Molecules Based on Quinoxaline Containing Amino Substitution at C‐2

A series of novel “drug‐like” small molecules based on quinoxaline containing amino substitution at C‐2 were synthesized. All these molecules were prepared either via the reaction of 2‐phenyl‐3‐(piperazin‐1‐yl)quinoxaline with acyl bromides or benzyl bromides or various carboxylic acids or via the reaction of 2‐chloro‐3‐phenylquinoxaline with various amines. The structures of these novel compounds were confirmed by spectral analysis. The strategy used is simple and efficient and afforded good yields of quinoxaline derivatives.     

Electron beam induced green luminescence and degradation study of CaS:Ce nanocrystalline phosphors for FED applications

Green luminescence and degradation of Ce³⁺ doped CaS nanocrystalline phosphors were studied with a 2 keV, 10 μA electron beam in an O₂ environment. The nanophosphors were synthesized by the co-precipitation method. The samples were characterized using X-ray diffraction, Transmission electron microscopy, Scanning electron microscopy/electron dispersive X-ray spectroscopy and Photoluminescence (PL) spectroscopy. Cubic CaS with an average particle size of 42 ± 2 nm was obtained. PL emission was observed at 507 nm and a shoulder at 560 nm with an excitation wavelength of 460 nm. Auger electron spectroscopy and Cathodoluminescence (CL) were used to monitor the changes in the surface composition of the CaS:Ce³⁺ nanocrystalline phosphors during electron bombardment in an O₂ environment. The effect of different oxygen pressures ranging from 1 × 10⁻⁸ to 1 × 10⁻⁶ Torr on the CL intensity was also investigated. A CaSO₄ layer was observed on the surface after the electron beam degradation. The CL intensity was found to decrease up to 30% of its original intensity at 1 × 10⁻⁶ Torr oxygen pressure after an electron dose of 50 C/cm². The formation of oxygen defects during electron bombardment may also be responsible for the decrease in CL intensity.     

Novel Copolymers of Styrene. 6. Some Oxy Ring-Disubstituted Butyl 2-Cyano-3-Phenyl-2-Propenoates

Novel trisubstituted ethylenes, oxy ring-disubstituted butyl 2-cyano-3-phenyl-2-propenoates, RPhCH=C(CN)CO₂C₄H₉ (where R is 4-methoxy-2-methyl, 4-methoxy-3-methyl, 3-ethoxy-4-methoxy, 4-ethoxy-3-methoxy, 3,4-dibenzyloxy, 2-benzyloxy-3-methoxy, and 3-benzyloxy-4-methoxy) were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and butyl cyanoacetate, and characterized by CHN analysis, IR, ¹H and ¹³C-NMR. All the ethylenes were copolymerized with styrene (M₁) in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, ¹H and ¹³C-NMR.

Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200-500°C range with residue (2-17 % wt.), which then decomposed in the 500-800°C range.     

Syntisis of 4-Demethoxy-7, 11-dideoxydaunomycinone

Our continued interest in the total synthesis of natural and unnatural antitumor anthracyclines¹ especially the aglycones such as daunomycinone (1)² and 4-demethoxydaunomycinone (2)³, 11-deoxydaunomycinone (3)⁴ and 4-demethoxy-11-deoxydaunomycinone (4)⁵ led us to probe methods of obtaining these products of absolute enantitomeric purity. Earlier it was demonstrated that the AB ring synthon 5 having a chiral centre on fusion with phthalic anhydride gave 4-demethoxy-7-deoxy-daunomycinone (6) with no loss of optical purity⁶ and the same was further transformed to 2 [7-(S)-9(S)].