Concerning the Basicity of 4-Dimethylaminoquinazoline Derivatives

 Two series of selected 4-N,N-dimethylamino-2-phenylquinazoline and 2-N,N-diethylamino-4-N,N-dimethylamino-quinazoline derivatives obtained in the reaction of substituted N-phenylbenzimidoyl chlorides or N¹,N¹-diethyl-N²-phenylchlorocarboxyamidines with N,N-dimethylcyanamide in the presence of TiCl₄ were examined in order to detect the protonation centre. The untypical correlations between pK _a and σ were supported by MNDO calculations and single crystal X-ray diffraction data and point to a protonation of the ring-N-atoms with delocalization of the positive charge into the N,N-dimethylamino group.     

O‐Phenyl (triphenylphosphoniomethyl)phosphonate phenol solvate: supramolecular structure generated by O—H...O,C—H...O and C—H...π(arene) hydrogen bonds

The title compound, C₂₅H₂₂O₃P₂·C₆H₆O, has a zwitterionic betaine‐like structure and crystallizes as a phenol solvate. The two molecular components are held together by an almost linear intermolecular O—H...O hydrogen bond. The structure also contains three weak C—H...O and two C—H...π(arene) interactions.     

trans‐Di­aqua­tetrakis(3,5‐di­methyl­pyrazole‐N2)­nickel(II) dichloride

The X‐ray structure analysis of [Ni(C₅H₈N₂)₄(H₂O)₂]Cl₂ was undertaken to elucidate the geometry around the Ni²⁺ ion. The molecule lies on a twofold axis which runs through the O—Ni—O atoms. The geometry around the Ni²⁺ ion is best described as slightly distorted tetragonal bipyramidal.     

Use of Reversed-Phase and Normal-Phase Preparative Thin-Layer Chromatography for Isolation and Purification of Coumarins from Peucedanum tauricum Bieb. Leaves

JPC – Journal of Planar Chromatography – Modern TLC -     

Comparison of different NaGdF4:Eu synthesis routes and their influence on its structural and luminescent properties

Eu³⁺:NaGdF₄ samples were obtained via co-precipitation in aqueous solution (CP), reversed micelle (RM) method, reaction between solid GdF₃ and NaF solution (SR) as well as a solid-state reaction at high temperatures (SS). The synthesised materials were characterised using X-ray powder diffractometry, TEM microscopy, infrared spectroscopy and TGA analysis. For discussion of optical properties excitation and emission spectra were recorded and emission decay times were measured. The CP and RM methods allow to obtain powders with crystallite size of ∼10 nm, which may be smoothly increased to about 1 μm during post-fabrication heat treatment. Differences in structural and especially in optical properties of phosphors prepared by different techniques are emphasised and applicability of wet-chemistry routes for synthesis of fluoride powders is argued.     

Off-axis metallic diffractive lens for terahertz beams

A diffractive optical element for off-axis focusing of terahertz radiation is presented. It was designed in a nonparaxial regime and manufactured in a metal slab by laser cutting of curved stripes. The optical function of the structure includes focusing and deflecting the illuminating beam of a chosen frequency in a particular place. Therefore, the element acts as both a spatial and a spectral filter; hence it is especially suitable for separating the terahertz signal from a broadband thermal load in passive detection devices. The experimental evaluation of the proposed diffractive lens by means of time-domain spectroscopy is presented and discussed.     

Ionic liquids as silica deactivating agents in gas chromatography for direct analysis of primary amines in water

Analysis of primary amines in aqueous samples remains a challenging analytical issue. The preferred approach by gas chromatography is hampered by interactions of free silanol groups with the highly reactive amine groups, resulting in inconsistent measurements. Here, we report a method for direct analysis of aliphatic amines and diamines in aqueous samples by gas chromatography (GC) with silanol deactivation using ionic liquids (ILs). ILs including trihexyl(tetradecyl)phosphonium bis 2,4,4-(trimethylpentyl)phosphinate (Cyphos IL-104), 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide [pmim][Tf(2)N] and N″-ethyl-N,N,N',N'-tetramethylguanidinium tris(pentafluoroethyl)trifluorophosphate [etmg][FAP] were tested as deactivating media for the GC liner. Solutions of these ILs in methanol were injected in the system prior to the analysis of primary amines. Butane-1,4-diamine (putrescine, BDA) was used as a reference amine. The best results were obtained using the imidazolium IL [pmim][Tf(2)N]. With this deactivator, excellent reproducibility of the analysis was achieved, and the detection limit of BDA was as low as 1mM. The applicability of the method was proven for the analysis of two different primary amines (C4-C5) and pentane-1,5-diamine.     

Optimization of Co2+ ions removal from water solutions via polymer enhanced ultrafiltration with application of PVA and sulfonated PVA as complexing agents

The paper presents the results of the studies of UF-complexation process applied for the removal of Co(2+) ions from water solutions. As binding agents for cobalt ions, the PVA polymer (M(w)=10,000) and its sulfonated form, synthesized in the laboratory, have been used. The method of experimental design and response surface methodology have been employed to find out the optimal conditions for the complexation process and to evaluate the interaction between the input variables, i.e., initial cobalt concentration, pH and amount of the polymer used, expressed as a polymer/Co(2+) ratio r. The data collected by the designed experiments showed that sulfonation of polymer has improved significantly the binding ability of PVA. The optimal conditions of cobalt ions complexation established by response surface model for non-sulfonated PVA polymer have been found to be as follows: the initial concentration of Co(2+)=5.70 mg L(-1), the ratio between polymer and metal ions, r=8.58 and pH=5.93. The removal efficiency of Co(2+) in these conditions was 31.81%. For sulfonated PVA polymer, the optimal conditions determined are as follows: initial concentration of [Co(2+)](0)=10 mg L(-1), r=1.2 and pH=6.5. For these conditions, a removal efficiency of 99.98% has been determined. The experiments showed that Co(2+) removal ability of sulfonated PVA was much higher than its non-sulfonated precursor. Although the polymer concentrations used in the tests with sulfonated PVA were approximately ten times lower than the non-sulfonated one, the removal efficiency of cobalt ions was significantly higher.     

New phosphorus-containing spherical carbon adsorbents as promising materials in drug adsorption and release

A simple method of preparation of new high surface area spherical carbon adsorbents is presented. The phosphoric acid activation upon hydrothermally formed spherules was employed to produce carbons having controlled high specific surface area (over 2100m(2)/g), large volumes of pores (1.2cm(3)/g), and high acidity. Prepared from sucrose materials show high adsorption capacities (i.e. 220mg/g(C)) toward paracetamol. It is proved that for these materials the contents of surface phosphorus are responsible for the reversibility of drug adsorption/release process.     

Transparent titanium dioxide/block copolymer modified epoxy-based systems in the long scale microphase separation threshold

Microphase separated epoxy-based materials modified with an amphiphilic poly(styrene-block-ethylene oxide) diblock copolymer (PS-b-PEO) with low amount of PEO-block as well as ternary systems modified with this block copolymer and containing via sol–gel in situ synthesized TiO₂ nanoparticles were prepared and characterized. The obtained results indicate that block copolymer had enough amount of PEO-block in order to achieve microphase separated materials for a high range of PS-b-PEO contents, morphologies changing from spherical micelles to long wormlike micelles passing through vesicles upon increasing copolymer amounts. In the case of 20 wt.% inorganic/organic epoxy-based materials, addition of synthesized TiO₂ nanoparticles into PS-b-PEO-(DGEBA/MCDEA) system led to location of the nanoparticles in PEO-block/epoxy-rich confined between two microphase separated PS-block-rich phases. Designed highly transparent multiphase inorganic/organic epoxy-based materials possess interesting specific properties such as high UV shielding efficiency and high water repellence.