Theoretical study of molecular interactions of phosphorus ylide with HF, HCN, and HN3

The molecular interactions between phosphorous ylide (PY) and HX molecules (X?=?F, CN, and N₃) were investigated using the MP2 method at 6-311++G(2d,2p) basis set. Three different patterns including non-classical hydrogen bond H···C, X···P interaction and classical hydrogen bond H···X were found for complex formation between PY and HX molecules. From the predicted models, stability of the H···C type complexes are greater than other types. Quantum theories of atoms in molecules and natural bond orbitals methods have been applied to analyze the intermolecular interactions. Good correlations have been found between the interaction energies (SE), the second-order perturbation energy E ⁽²⁾, and the charge transfer qCT in the studied systems.     

Green synthesis of Fe3O4/ZnO magnetic core-shell nanoparticles by Petasites hybridus rhizome water extract and their application for the synthesis of pyran derivatives: Investigation of antioxidant and antimicrobial activity

In this research, Fe₃O₄/ZnO magnetic core-shell nanoparticles (Fe₃O₄/ZnO MCNPs) were synthesized through a green method using Petasites hybridus rhizome water extract as a reducing and stabilizing agent. The morphology and size of the Fe₃O₄/ZnO MCNPs was identified by X-ray diffraction, scanning electron microscopy, and Energy-dispersive X-ray spectroscopy (EDX) analysis. The catalytic activity of the Fe₃O₄/ZnO MCNPs was evaluated in the efficient and green preparation of pyran derivatives in excellent yield using three-component reactions of dimedone, aldehydes, and malononitrile in ethanol at room temperature. The ability of some synthesized compounds to scavenge the 2,2-diphenyl-1-picrylhydrazyl radical was measured and the results proved this observation. Moreover, the antimicrobial activity of some synthesized compounds was proved by employing the disk diffusion test on Gram-positive and Gram-negative bacteria. The results for the disk diffusion test showed that compounds ( 4c, 4d, 4f and 4g ) prevented bacterial growth.     

Theoretical study of molecular interactions of sulfur ylide with HSX (X = F, Cl, and Br) molecules

The molecular interactions between sulfur ylide (SY) and HSX molecules (X = F, Cl and Br) were investigated using the MP2 method with the 6-311++G (2d, 2p) basis set. The SY (CH₂=SH₂) have two reactive sites: CH₂ (denoted as C-interaction) and SH₂ (S-interaction) that both could interact with three atoms of HSX molecules. The results show that S···C, X···C, and H···C interactions (C-interactions) is preference over the X···S, H···S, and H···X interactions. Quantum theories of atoms in molecules and natural bond orbitals methods have been applied to analyze the intermolecular interactions. Good correlations have been found between the interaction energies, the second-order perturbation energies E⁽²⁾, and the charge transfer qCT in the studied systems.     

Hydrolytic Transformation of Microporous Metal–Organic Frameworks to Hierarchical Micro‐ and Mesoporous MOFs

A new approach to the synthesis of hierarchical micro‐ and mesoporous MOFs from microporous MOFs involves a simple hydrolytic post‐synthetic procedure. As a proof of concept, a new microporous MOF, POST‐66(Y), was synthesized and its transformation into a hierarchical micro‐ and mesoporous MOF by water treatment was studied. This method produced mesopores in the range of 3 to 20 nm in the MOF while maintaining the original microporous structure, at least in part. The degree of micro‐ and mesoporosity can be controlled by adjusting the time and temperature of hydrolysis. The resulting hierarchical porous MOF, POST‐66(Y)‐wt, can be utilized to encapsulate nanometer‐sized guests such as proteins, and the enhanced stability and recyclability of an encapsulated enzyme is demonstrated.     

Application of the UNIFAC model for prediction of surface tension and thickness of the surface layer in the binary mixtures

The specific sorption of Eu(III) and Y(III) on γ-alumina was investigated with solid-state (1)H NMR. Solution pH was shown to influence the recorded (1)H NMR spectra of γ-alumina, and thus, metal ion-containing samples were prepared under constant pH conditions, 8.00±0.05. The metal ion concentration in the samples was varied between 6.58×10(-7) M - 3.95×10(-4) M in case of Y(3+) and 6.58×10(-8) M - 1.32×10(-4) M in case of Eu(3+). The mineral concentration was kept constant at 4 g/l. After separation of the liquid phase, the samples were dried under vacuum to remove physisorbed water from the mineral surface. However, even after 48 h of drying at 150°C and 20 mTorr, water was still detected in the proton spectra as two distinct peaks with chemical shifts at 1.3 and 0.9 ppm. The europium addition to the γ-alumina samples induced significant spectral changes in comparison with yttrium-containing samples. These changes were attributed to the paramagnetism of europium rather than to complexation reactions occurring on the mineral surface. Proton spectra obtained for yttrium samples were therefore used to detect the spectral changes induced by the sorption reaction itself. The results revealed a large distribution of protons being removed from the mineral surface upon yttrium complexation. Removed protons were assigned to both bridging surface hydroxyls such as (Al(VI))(2)-OH as well as to terminal hydroxyls, e.g., of type Al(VI)-OH. Acidic protons belonging to (Al(VI))(3)-OH groups were not observed to participate in the surface reaction.     

Hydrothermally grown nano-manganese oxide on clinoptilolite for low-temperature propane-selective catalytic reduction of NO<Subscript>x</Subscript>

A novel nano-size Mn_xO_y/clinoptilolite catalyst of high activity for propane-SCR reaction of NO_x at low temperatures has been synthesized by a hydrothermal method in a temperature range of 80–180 °C. The optimum synthesis temperature resulting in maximum NO_x conversion was 150 °C. An optimum manganese oxide loading of 0.2 wt.% results in the best catalytic behavior (71% NO_x conversion). All catalysts exhibited an optimal propane-SCR reaction temperature of 200 °C. The optimum catalyst produces no detectable CO (GHSV 27,000 h) at 200 °C. Manganese in the optimum catalyst exists as Mn²⁺ (37.8%), Mn³⁺ (14.2%), and Mn⁴⁺ (48%).

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Graphical abstract Flake-like manganese oxide nanostructures (indicated by an arrow in the TEM picture) next to the clinoptilolite zeolite sheet-like crystals result in a promising low-temperature propane-selective catalytic reduction of NO_x.

     

Multicomponent reactions for the synthesis of new cyclopentadienephosphonate derivatives in water

A series of polysubstituted cyclopentadienephosphonate derivatives were synthesized via one-pot multicomponent reactions of primary amines and phosphites with activated acetylenic compounds in water as the solvent at room temperature.

Particularly valuable features of this method include high yields of products, broad substrate scope, short reaction time and a straightforward procedure.     

Design and synthesis of phenoxymethybenzoimidazole incorporating different aryl thiazole-triazole acetamide derivatives as α-glycosidase inhibitors

Molecular Diversity - A novel series of phenoxymethybenzoimidazole derivatives (9a-n) were rationally designed, synthesized, and evaluated for their α-glycosidase inhibitory activity. All...     

Solvent bar microextraction combined with high‐performance liquid chromatography for preconcentration and determination of pramipexole in biological samples

A simple, rapid and sensitive analytical method for preconcentration and determination of pramipexole in different biological samples has been developed using solvent bar microextraction (SBME) combined with HPLC‐UV. The target drugs were extracted from 10 mL of basic aqueous sample solution into an organic extracting solvent located inside the pores of a polypropylene hollow fiber, then back‐extracted into an acidified aqueous solution in the lumen of the hollow fiber. In order to obtain high extraction efficiency, the effect of different variables on the extraction efficiency was studied simultaneously using an experimental design. The experimental parameters of SBME were optimized using a Box–Behnken design after a Plackett–Burman screening design. Under the optimized conditions, an enrichment factor up to 96 was achieved and the relative standard deviation of the method was 4.64% (n = 5). The linear range was 0.05–2000 µg/L with a correlation coefficient (r) of 0.987. Finally, the applicability of the proposed method was evaluated by extraction and determination of pramipexole in plasma and urine samples. The results indicated that SBME method has excellent clean‐up and high preconcentration factor and can serve as a simple and sensitive method for analysis of pramipexole in biological samples. Copyright © 2013 John Wiley & Sons, Ltd.     

Nitroimidazoles X . Syntheses of substituted 2-(1-methyl-5-nitro-2-imidazolyl)quinolines

Reduction of substituted-2-nitrobenzaldehyde (1) afforded substituted-2-aminobenzaldehyde (2) . Reaction of compound 2 with 2-acetyl-1-methyl-5-nitroimidazole (3) under basic conditions afforded substituted 2-(1-methyl-5-nitro-2-imidazolyl)quinolines 4 . Reaction of compound 4 (R = X) with hydrogen peroxide in acetic acid afforded compound 5 which was transformed to compound 6 with phosphorus oxychloride.