Utility of 4‐Benzylidene‐2‐phenyl‐5(4H)‐oxazolone in Synthesis of Triazine,Oxadiazole and Imidazole Derivatives of Anticipated Biological Activity

Treatment of oxazolone 1 with hydrazine hydrate at room temperature gave the (Z)‐configurated isomer hydrazide (Z)‐ 3 (high yield). However, refluxing 1 with hydrazine hydrate yielded the (E)‐configurated isomer hydrazide (E)‐ 2 (low yield).The hydrazide derivative (Z)‐ 3 has been utilized as synthon for the synthesis of 1,2,4‐triazinone, imidazolone, and oxadiazole derivatives through appropriate routes. The thiosemicarbazide and semicarbazide derivatives are synthesized by different routes. The structures of the new compounds were established on the basis of IR, ¹H‐NMR, mass spectral data, and elemental analysis.     

Action of Hydrazines on 2‐(2‐Oxindolin‐3‐ylidene)malononitrile, (E,Z)‐Ethyl 2‐cyano‐2‐(2‐oxindolin‐3‐ylidene)acetate and Isatin‐β‐thiosemicarbazone as a Source of Spiro Indoline‐pyrazole Systems

2‐(2‐Oxindolin‐3‐ylidene)malononitrile ( 1a ) or (E,Z)‐ethyl 2‐cyano‐2‐(2‐oxindolin‐3‐ylidene)acetate ( 1b ) or isatin‐β‐thiosemicarbazone ( 1c ) undergoes reactions with prototype hydrazine hydrate itself and some of its simple congeners to give hydrazone derivatives bearing indoline‐2‐one moiety ( 2 ). The hydrazone derivatives ( 2 ) when heated with acetyl acetone or ethyl acetoacetate in dry pyridine afforded the spiro indoline derivatives ( 3a , 3b ). Also, cinnoline derivative ( 9 ) is obtained by action of hydrazine hydrate on the N‐acetyl derivative of ( 6a ). The structures of the newly synthesized compounds were evaluated by IR, ¹H‐NMR spectroscopy, mass spectra and elemental analyses.     

A Validated TLC-Densitometric Method for the Simultaneous Determination of Formoterol Fumarate and Budesonide in Pressurized Metered-Dose Inhaler

JPC – Journal of Planar Chromatography – Modern TLC - A simple and robust thin-layer chromatography (TLC) method has been developed and validated for the simultaneous quantitative...     

On von Neumann regular elements in <Emphasis Type="Italic">f</Emphasis>-rings

Let B be an Archimedean reduced f-ring. A positive element \({\omega}\) in B is said to satisfy the property \({(\ast)}\) if for every f-ring A with identity e and every \({\ell}\)-group homomorphism \({\gamma : A \rightarrow B}\) with \({\gamma(e) = \omega}\), there exists a unique \({\ell}\)-ring homomorphism \({\rho: B \rightarrow B}\) such that \({\gamma = \omega \rho}\) and \({\rho(e)^{\perp \perp} = \omega^{\perp \perp}}\). Boulabiar and Hager proved that any (positive) von Neumann regular element in B satisfies the property \({(\ast)}\) and proved that the converse holds in the C(X)-case. In this regard, they asked about this converse in the general case. Our main purpose in this note is to prove, via a counter-example, that the converse in question fails in general. In addition, we shall take the opportunity to extend the direct result obtained by Boulabiar and Hager, and to get the C(X)-case we were talking about in an easier way.     

Synthesis,Characterization, and Antimicrobial Evaluation of Some Novel 4-Hydroxyquinolin-2(1H)-ones

Vilsmeier–Haack formylation of 3-acetyl-1-methyl-4-hydroxyquinolin-2(1H)-one (2) produced the novel 6-methyl-4,5-dioxo-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carboxaldehyde (3). Reactions of carboxaldehyde 3 with a diversity of nucleophilic reagents were studied and a variety of products were obtained via ring-opening, ring-closing (RORC) sequence. Also, some novel heteroannulated pyrano[3,2-c]quinolines were prepared. Structures of the new synthesized products were deduced on the basis of their analytical and spectral data.     

Polyethylenimine-impregnated mesoporous silica: effect of amine loading and surface alkyl chains on CO2 adsorption

Poly(ethyleneimine) (PEI) supported on pore-expanded MCM-41 whose surface is covered with a layer of long-alkyl chains was found to be a more efficient CO(2) adsorbent than PEI supported on the corresponding calcined silica and all PEI-impregnated materials reported in the literature. The layer of surface alkyl chains plays an important role in enhancing the dispersion of PEI, thus decreasing the diffusion resistance. It was also found that at low temperature, adsorbents with relatively low PEI contents are more efficient than their highly loaded counterparts because of the increased adsorption rate. Extensive CO(2) adsorption-desorption cycling showed that the use of humidified feed and purge gases affords materials with enhanced stability, despite limited loss due to amine evaporation.     

On the specificity of the amide VI band for the secondary structure of proteins

In this work we analyzed the specificity of the amide VI band for different types of secondary structure elements in protein structures. This band involves the bending motion of the CO group of the peptide chain that is typically observed in the spectral region from 590 to 490 cm⁻¹. The infrared absorbance spectra of a set of polypeptide model compounds of well known secondary structure was obtained at defined pH, including poly (l-lysine), poly (l-tyrosine), poly (l-alanine) and poly (l-histidine). In addition spectra of membrane proteins from the respiratory chain, namely the NADH:ubiquinone oxidoreductase, the cytochrome c oxidase and its Cu_A fragment, the cytochrome bc₁ complex, a Rieske-type protein and in addition myoglobin, have been comparatively investigated. The systematic analysis of the amide VI band of the polypeptides and the proteins allowed correlating the signal appearing at ∼525 cm⁻¹ to α-helical structures and signals at ∼545 cm⁻¹ to β-sheet contributions. Random coils have been found to contribute at ∼535 cm⁻¹ while the β-turns were observed at ∼560 cm⁻¹.     

Enantiomeric Thin-Layer Chromatographic Assay of Escitalopram in Presence of “In-Process Impurities”

JPC – Journal of Planar Chromatography – Modern TLC - A simple, rapid and precise thin-layer chromatographic (TLC) method for analysis of escitalopram oxalate (ESC-OX) (S-enantiomer) in...     

Adsorption of CO<Subscript>2</Subscript>-containing gas mixtures over amine-bearing pore-expanded MCM-41 silica: application for CO<Subscript>2</Subscript> separation

Adsorption of CO₂, N₂, CH₄ and H₂ on triamine-grafted pore-expanded MCM-41 mesoporous silica (TRI-PE-MCM-41) was investigated at room temperature in a wide range of pressure (up to 25 bar) using gravimetric measurements. The material was found to exhibit high affinity toward CO₂ in comparison to the other species over the whole range of pressure. Column-breakthrough dynamic measurements of CO₂-containing mixtures showed very high selectivity toward CO₂ over N₂, CH₄ and H₂ at CO₂ concentrations within the range of 5 to 50%. These conditions are suitable for effective removal of CO₂ at room temperature from syngas, flue gas and biogas using temperature swing (TS) or temperature-pressure swing (TPS) regeneration mode. Moreover, TRI-PE-MCM-41 was found to be highly stable over hundreds of adsorption-desorption cycles using TPS as regeneration mode.     

The quest for modular nanocages: tbo-MOF as an archetype for mutual substitution, functionalization, and expansion of quadrangular pillar building blocks

A new blueprint network for the design and synthesis of porous, functional 3D metal-organic frameworks (MOFs) has been identified, namely, the tbo net. Accordingly, tbo-MOFs based on this unique (3,4)-connected net can be exclusively constructed utilizing a combination of well-known and readily targeted [M(R-BDC)](n) MOF layers [i.e., supermolecular building layers (SBLs)] based on the edge-transitive 4,4 square lattice (sql) (i.e., 2D four-building units) and a novel pillaring strategy based on four proximal isophthalate ligands from neighboring SBL membered rings (i.e., two pairs from each layer) covalently cross-linked through an organic quadrangular core (e.g., tetrasubstituted benzene). Our strategy permits the rational design and synthesis of isoreticular structures, functionalized and/or expanded, that possess extra-large nanocapsule-like cages, high porosity, and potential for gas separation and storage, among others. Thus, tbo-MOF serves as an archetypal tunable, isoreticular MOF platform for targeting desired applications.