Schiff bases of indoline-2,3-dione: potential novel inhibitors of Mycobacterium tuberculosis (Mtb) DNA gyrase

In the present study a series of Schiff bases of indoline-2,3-dione were synthesized and investigated for their Mtb gyrase inhibitory activity. Promising inhibitory activity was demonstrated with some of these derivatives, which exhibited IC(50) values ranging from 50-157 mM. The orientation and the ligand-receptor interactions of such molecules within the Mtb DNA gyrase A subunit active site were investigated applying a multi-step docking protocol using Molecular Operating Environment (MOE) and Autodock4 docking software. The results revealed the importance of the isatin moiety and the connecting side chain for strong interactions with the enzyme active site. Among the tested compounds the terminal aromatic ring benzofuran showed the best activity. Promising new leads for developing a novel class of Mtb gyrase inhibitors were obtained from Schiff bases of indoline-2,3-dione.     

Microwave-assisted one-step synthesis of fenamic acid hydrazides from the corresponding acids

A facile and efficient method for synthesis of fenamic acid hydrazides from their acids in one-step reaction under microwave irradiation and solvent-free conditions was developed. Compared with the two-step conventional heating method, the process was simple, the reaction time was very short and the yields were almost quantitative.     

Ultra high amorphous silicon passivation quality of crystalline silicon surface using in‐situ post‐deposition treatments

A parametric study of post‐deposition hydrogen plasma treatment of intrinsic a:Si:H films is performed. We demonstrate a significant improvement in passivation of c‐Si(100) promoting epitaxy after an in‐situ hydrogen plasma treatment depending mainly on the pressure and slightly on the power. Plasma diagnostic indicates an increase of H_α* signal with high power and low pressure. However, our analysis reveals a better hydrogen incorporation with high pressure and a slight increase in monohydride with high power. Longer H₂ plasma duration up to 50 s shows no detrimental effect on the passivation quality. Optimizing the in‐situ H₂ plasma treatment, high minority carrier lifetime over 15 ms was achieved after short thermal annealing. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Exploring Supramolecular Self‐Assembly of Tetraarylporphyrins by Halogen Bonding: Crystal Engineering with Diversely Functionalized Six‐Coordinate Tin(L)2–Porphyrin Tectons

This study targets the construction of porphyrin assemblies directed by halogen bonds, by utilizing a series of purposely synthesized Sn(axial ligand)₂–(5,10,15,20‐tetraarylporphyrin) [Sn(L)₂‐TArP] complexes as building units. The porphyrin moiety and the axial ligands in these compounds contain different combinations of complimentary molecular recognition functions. The former bears p‐iodophenyl, p‐bromophenyl, 4′‐pyridyl, or 3′‐pyridyl substituents at the meso positions of the porphyrin ring. The latter comprises either a carboxylate or hydroxy anchor for attachment to the porphyrin‐inserted tin ion and a pyridyl‐, benzotriazole‐, or halophenyl‐type aromatic residue as the potential binding site. The various complexes were structurally analyzed by single‐crystal X‐ray diffraction, accompanied by computational modeling evaluations. Halogen‐bonding interactions between the lateral aryl substituents of one unit of the porphyrin complex and the axial ligands of neighboring moieties was successfully expressed in several of the resulting samples. Their occurrence is affected by structural (for example, specific geometry of the six‐coordinate complexes) and electronic effects (for example, charge densities and electrostatic potentials). The shortest intermolecular I???N halogen‐bonding distance of 2.991 Å was observed between iodophenyl (porphyrin) and benzotriazole (axial ligand) moieties. Manifestation of halogen bonds in these relatively bulky compounds without further activation of the halophenyl donor groups by electron‐withdrawing substituents is particularly remarkable.     

Research and Development with Stock-Dependent Spillovers and Price Competition in a Duopoly

This paper investigates the research and development accumulation and pricing strategies of two firms competing for consumer demand in a dynamic framework. A firm’s research and development is production-cost-reducing and can benefit from part of the competitor’s research and development stock without payment. We consider decisions in a game characterized by Nash equilibrium. In this dynamic game, a player’s action depends on whether the competitor’s current research and development stock are observable. If the competitor’s current research and development stock are not observable or observable only after a certain time lag, a player’s action can be solely based on the information on the current period t (open-loop strategy). In the converse case, it can also include the information on the competitor’s reaction to a change in the current value of the state vector (closed-loop strategy), which allows for strategic interaction to take place throughout the game. Given the cumulative nature of research and development activities, a primary goal of this paper is to determine whether, regardless of the observability of the competitor’s current research and development stock, free research and development spillovers generate a lower level of scientific knowledge than research and development appropriability. A second objective of the paper is to determine how the observability of the rival’s current research and development stock affects a firm’s research and development and pricing decisions and payoffs under imperfect research and development appropriability.     

Dendronephthols A–C,new sesquiterpenoids from the Red Sea soft coral Dendronephthya sp.

Three new ylangene-type sesquiterpenoids: dendronephthol A (7,13-dihydroxy-3,4-dihydro-α-ylang-5-one) (1), dendronephthol B (6,7,13-trihydroxy-3,4-dihydro-α-ylangene) (2), and dendronephthol C (6,7,13-trihydroxy-α-ylang-5-one) (3), together with two known compounds: dendronesterone A and cholesterol were isolated from the CHCl₃ fraction of Red Sea soft coral Dendronephthya sp. (Nephtheidae). The structures of the new compounds were established on the basis of one- and two-dimensional NMR spectroscopic studies (¹H, ¹³C, DEPT, COSY, HSQC, HMBC, and NOESY) as well as MS spectroscopy and by comparison of the spectral data with those of related known compounds. Compounds 1 and 3 showed cytotoxic activity against the murine lymphoma L5187Y cancer cell line with ED₅₀ values of 8.4 and 6.8 μg/mL, respectively.     

Chemistry of Phosphonium Ylides. Part 39: Facile Synthesis of Aziridine,Pyridine, Pyrolotriazole Chromenones and Azaphosphinin Chromenones as Antitumor Agents

The reaction of 4‐azido‐2‐oxo‐2H‐chromene‐3‐carbaldehyde with the active nucleophilic phosphacumulenes yielded the corresponding phosphanylidene‐aziridines and chromeno‐pyrolo‐triazoles. On the other hand, the reaction of the allylic phosphonium ylide, hexaphenylcarbodiphosphorane with the azido compound, was also undertaken. In this case, the phosphanylidene‐chromeno‐triazinone was obtained. Further assessment of these new compounds against (breast: MCF‐7 and liver: HPEG2) human solid tumor cell lines is necessary.     

Co3O4/SiO2 nanocomposites for supercapacitor application

In this study, Co₃O₄/SiO₂ nanocomposites have been successfully synthesized by citrate–gel method by utilizing SiO₂ matrix for Co₃O₄ embedment. Spectroscopy analyses confirm the formation of high crystalline Co₃O₄ nanoparticles; meanwhile, microscopy findings reveal that the Co₃O₄ nanoparticles are embedded in SiO₂ matrix. Electrochemical properties of the Co₃O₄/SiO₂ nanocomposites were carried out using cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS) in 5 M KOH electrolyte. The findings show that the charge storage of Co₃O₄/SiO₂ nanocomposites is mainly due to the reversible redox reaction (pseudocapacitance). The highest specific capacitance of 1,143 F g ^?1 could be achieved at a scan rate of 2.5 mV s^?1 in the potential region between 0 and 0.6 V. Furthermore, high-capacitance retention (>92 %) after 900 continuous charge–discharge tests reveals the excellent stability of the nanocomposites. It is worth noting from the EIS measurements that the nanocomposites have low ESR value of 0.33 Ω. The results manifest that Co₃O₄/SiO₂ nanocomposites are the promising electrode material for supercapacitor application.     

New one step synthesis of 3,5‐disubstituted pyrazoles under microwave irradiation and classical heating

A convenient one pot procedure for the synthesis of 3,5-disubstituted pyrazoles by condensation of chalcones, hydrazine hydrate and sulfur in ethanol under microwave irradiation and conventional heating method is reported. The hydrogen sulfide is produced during the reaction. The pyrazoles are obtained in good yields and excellent state of purity. The structures of new compounds were confirmed by IR, ¹H, and ¹³C NMR, MS and elemental analysis.     

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.