Chemistry of phosphorus ylides. Part 25 [1]. Interaction of hexaphenylcarbodiphosphorane with carbonyls, hydrazone, and Mannich bases. A synthesis of phosphoranylidenes, phosphobetaines, and oxaphosphinin

The reaction of the allylic hexaphenylcarbodiphosphorane with carbonyls afforded the corresponding phosphoranylidene derivatives. On the other hand, the stable phosphorbetaines were obtained when the bisphosphorane was allowed to react with the α-diketone and triketone. The azaphosphoranylidene was isolated from the reaction of the bisphosphorane with hydrazone. Moreover, the bisphosphorane reacted with niclosamide and quinoline Mannich bases with the formation of the oxaphosphinins. When the Wittig reaction was performed with the new phosphoranes, the corresponding exocyclic olefins were obtained. On the other hand, the oxaphosphinins were produced when the phosphoranes were treated under the condition of a Hoffmann degradation reaction. Correspondence: Medhat M. Said, Department of Organometallic and Organometalloide Chemistry, National Research Centre, El-Tahrir Street, Dokki, Cairo, Egypt.     

Sulfur isotope fractionation during incorporation of sulfur nucleophiles into organic compounds

(34)S enrichment is shown to occur during sulfurization reactions and for the first time conclusively attributed to an isotope equilibrium effect rather than selective addition of (34)S enriched nucleophiles.     

Low reactivity of non-bridging oxygen defects on stoichiometric silica surfaces

Using ab initio molecular dynamics simulations we demonstrate that surfaces of stoichiometric silica exhibiting non-bridging oxygen defects can be surprisingly resistant to attack by water.     

Well-posedness and stability of nonautonomous past systems with unbounded operators in the delay term

Semigroup Forum - We define a semigroup S to be right ideal Howson if the intersection of any two finitely generated right ideals, or, equivalently, any two principal right ideals, is again...     

Aqueous synthesis and enhanced photocatalytic activity of ZnO/Fe2O3 heterostructures

We report a facile synthesis of ZnO/Fe₂O₃ heterostructures based on the hydrolysis of FeCl₃ in the presence of ZnO nanoparticles. The material structure, composition, and its optical properties have been examined by means of transmission electron microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and diffuse reflectance UV–visible spectroscopy. Results obtained show that 2.9 nm-sized Fe₂O₃ nanoparticles produced assemble with ZnO to form ZnO/Fe₂O₃ heterostructures. We have evaluated the photodegradation performances of ZnO/Fe₂O₃ materials using salicylic acid under UV-light. ZnO/Fe₂O₃ heterostructures exhibited enhanced photocatalytic capabilities than commercial ZnO due to the effective electron/hole separation at the interfaces of ZnO/Fe₂O₃ allowing the enhanced hydroxyl and superoxide radicals production from the heterostructure.     

Efficacy of Ficus spp. on renal injury induced by hypercholesterolaemia

The ethanol and hexane extracts of Ficus microcarpa, Ficus religiosa and Ficus mysorensis leaves were evaluated against renal injury induced by hypercholesterolaemia. Phytochemical screening of the investigated plants was undertaken. For the in vivo study, all rats were orally given cholesterol (30?mg?kg?1 body weight, BW) and leaves extract (500?mg?kg?1 BW) five times per week for 9 weeks. Hypercholesterolaemic rats showed significant increases in urea nitrogen and creatinine while serum protein and albumin levels, nitric oxide (NO), Na?-K?-ATPase and phospholipids in kidney tissue were all decreased. Treatment with leaves extract improved kidney function indices (urea nitrogen, creatinine, serum protein and albumin), kidney disorder biochemical parameters (NO, Na?-K?-ATPase and phospholipids), haematological profile (haemoglobin, RBCs and WBCs) and kidney histopathology. In conclusion, Ficus spp. succeeded in improving renal injury induced by hypercholesterolaemia, with the most potent effects seen while using Ficus microcarpa hexane extract.     

Synthesis, Characterisation and Electrical Properties of Supramolecular DNA-Templated Polymer Nanowires of 2,5-(Bis-2-thienyl)-pyrrole

Supramolecular polymer nanowires have been prepared by using DNA-templating of 2,5-(bis-2-thienyl)-pyrrole (TPT) by oxidation with FeCl(3) in a mixed aqueous/organic solvent system. Despite the reduced capacity for strong hydrogen bonding in polyTPT compared to other systems, such as polypyrrole, the templating proceeds well. FTIR spectroscopic studies confirm that the resulting material is not a simple mixture and that the two types of polymer interact. This is indicated by shifts in bands associated with both the phosphodiester backbone and the nucleobases. XPS studies further confirm the presence of DNA and TPT, as well as dopant Cl(-) ions. Molecular dynamics simulations on a [{dA(24) :dT(24) }/{TPT}(4) ] model support these findings and indicate a non-coplanar conformation for oligoTPT over much of the trajectory. AFM studies show that the resulting nanowires typically lie in the 7-8?nm diameter range and exhibit a smooth, continuous, morphology. Studies on the electrical properties of the prepared nanowires by using a combination of scanned conductance microscopy, conductive AFM and variable temperature two-terminal I-V measurements show, that in contrast to similar DNA/polymer systems, the conductivity is markedly reduced compared to bulk material. The temperature dependence of the conductivity shows a simple Arrhenius behaviour consistent with the hopping models developed for redox polymers.     

Synthesis,Characterisation and Electrical Properties of Supramolecular DNA‐Templated Polymer Nanowires of 2,5‐(Bis‐2‐thienyl)‐pyrrole

Supramolecular polymer nanowires have been prepared by using DNA‐templating of 2,5‐(bis‐2‐thienyl)‐pyrrole (TPT) by oxidation with FeCl₃ in a mixed aqueous/organic solvent system. Despite the reduced capacity for strong hydrogen bonding in polyTPT compared to other systems, such as polypyrrole, the templating proceeds well. FTIR spectroscopic studies confirm that the resulting material is not a simple mixture and that the two types of polymer interact. This is indicated by shifts in bands associated with both the phosphodiester backbone and the nucleobases. XPS studies further confirm the presence of DNA and TPT, as well as dopant Cl^? ions. Molecular dynamics simulations on a [{dA₂₄:dT₂₄}/{TPT}₄] model support these findings and indicate a non‐coplanar conformation for oligoTPT over much of the trajectory. AFM studies show that the resulting nanowires typically lie in the 7–8 nm diameter range and exhibit a smooth, continuous, morphology. Studies on the electrical properties of the prepared nanowires by using a combination of scanned conductance microscopy, conductive AFM and variable temperature two‐terminal I–V measurements show, that in contrast to similar DNA/polymer systems, the conductivity is markedly reduced compared to bulk material. The temperature dependence of the conductivity shows a simple Arrhenius behaviour consistent with the hopping models developed for redox polymers.     

XPS evidence for structure-performance relationship in selective hydrogenation of crotonaldehyde to crotyl alcohol on platinum systems supported on natural phosphates

The design of the oppositely charged ink particles based on titanium dioxide and carbon black for the monochrome electrophoretic display (EPD) was reported. The white ink particles with acidic surface and black ink particles with basic surface were synthesized and sterically stabilized by long alkyl chains, which were charged oppositely by mixing with basic surfactant (OLOA 1200) and acidic surfactant (Span 80), respectively. The electrophoretic mobility and the Zeta potential were −3.87 × 10⁻¹⁰ m² V⁻¹ s⁻¹ and −25.1 mV for the white ink particles, 3.79 × 10⁻¹⁰ m² V⁻¹ s⁻¹ and 24.6 mV for the black ink particles. In addition, the block copolymer, poly(lauryl methacrylate)-b-poly(2-(dimethylamino)ethyl methacrylate) (PLMA-b-PDMAEMA) synthesized by atom transfer radical polymerization (ATRP), was first incorporated in the modification of the pigments for the fine encapsulation. Then, a stable dual-particle electronic ink with contrast ratio of 120:1 was prepared and encapsulated with the gelatin (GE)/sodium carboxymethylcellulose (NaCMC)/sodium dodecyl sulfate (SDS) microcapsules by complex coacervation method. Finally, the matrix character display prototype driven at a low voltage exhibited excellent performance, the contrast ratio of which was 8:1 at 9 V DC.     

Synthesis and antitumor activity of some novel hydrazide, 1,2‐dihydropyridine,chromene, and benzochromene derivatives

2‐Cyano‐N′‐[1‐(substitutedphenyl)ethylidene]acetohydrazide 2a , 2b , 2c were obtained via reaction of acetophenone derivatives 1a , 1b , 1c with cyanoacetic acid hydrazide. The hydrazidehydrazone derivative 2a underwent a novel series of heterocyclization reactions via its reaction with aromatic aldehydes and/or arylidenemalononitriles to produce arylidene and dihydropyridine derivatives 3 5l , respectively. Structures of the newly synthesized compounds were confirmed by elemental analyses, IR, ¹³C‐NMR, ¹H‐NMR and mass spectral data. All the newly synthesized compounds were evaluated for their in‐vitro antitumor activity against Ehrlich Ascities Carcinoma (EAC) cells. Some of them showed interesting cytotoxic activity compared with Doxorubicin (CAS 23214‐92‐8) as a reference drug. J. Heterocyclic Chem., (2011).