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101.
The synthesis of well-defined luminescent organoboron polymers via a novel three-step procedure starting from silylated polystyrene is reported. Highly selective borylation of poly(4-trimethylsilylstyrene) (PS-Si), followed by replacement of the bromine substituents in poly(4-dibromoborylstyrene) (PS-BBr) with substituted thienyl groups (R = H, 3-hexyl, 5-hexyl), and final introduction of the 8-hydroxyquinolato moiety yields a series of new organoboron quinolate polymers in 67-83% isolated yield. The hexyl-substituted polymers are highly soluble and solution-processable yielding thin films that efficiently emit light at 513-514 nm upon excitation at 395 nm. 相似文献
102.
Piotr Kurcok Andrzej Matuszowicz Zbigniew Jedliski 《Macromolecular rapid communications》1995,16(3):201-206
The anionic polymerization of 2-oxetanone and 4-methyl-2-oxetanone initiated with the potassium hydride/18-crown-6 complex was investigated. The α-proton abstraction of the monomer was found to proceed at the initiation step of this polymerization. The salt of the unsaturated carboxylic acid formed initiates further propagation, leading to functionalized polyesters with unsaturated, dead end-groups. 相似文献
103.
Marcin Rojkiewicz Piotr Ku Maria Ksiek Joachim Kusz 《Acta Crystallographica. Section C, Structural Chemistry》2022,78(1):56-62
Cathinones belong to a group of compounds of great interest in the new psychoactive substances (NPS) market. Constant changes to the chemical structure made by the producers of these compounds require a quick reaction from analytical laboratories in ascertaining their characteristics. In this article, three cathinone derivatives were characterized by X-ray crystallography. The investigated compounds were confirmed as: 1-[1-(4-methylphenyl)-1-oxohexan-2-yl]pyrrolidin-1-ium chloride ( 1 , C17H26NO+·Cl?, the hydrochloride of 4-MPHP), 1-(4-methyl-1-oxo-1-phenylpentan-2-yl)pyrrolidin-1-ium chloride ( 2 ; C16H24NO+·Cl?, the hydrochloride of α-PiHP) and methyl[1-(4-methylphenyl)-1-oxopentan-2-yl]azanium chloride ( 3 ; C13H20NO+·Cl?, the hydrochloride of 4-MPD). All the salts crystallize in a monoclinic space group: 1 and 2 in P21/c, and 3 in P21/n. To the best of our knowledge, this study provides the first detailed and comprehensive crystallographic data on salts 1 – 3 . 相似文献
104.
Michał Pieckowski Piotr Kowalski Ilona Olędzka Natalia Miękus-Purwin Alina Plenis Anna Roszkowska Tomasz Bączek 《Electrophoresis》2022,43(9-10):990-997
Mitotane is a cytotoxic drug used in the treatment of inoperable adrenocortical carcinoma, it inhibits steroidogenesis as well, and therefore monitoring the level of steroid hormones in patients treated with mitotane is a crucial point of therapy. Hence, we have developed a simple, fast, and efficient electrophoretic method combined with reverse polarity sweeping as online preconcentration technique and dispersive liquid–liquid microextraction for the simultaneous determination of mitotane, its main metabolite DDA, and five steroid hormones (progesterone, testosterone, epitestosterone, cortisol, and corticosterone) in urine samples. In addition, a new sample matrix consisting of β-CD2SDS1 complexes for a high hydrophobic compounds solubilization was developed. Approach based on the application of β-cyclodextrin and SDS complex of a ratio 2:1 allowed for hydrodynamic injection into the capillary of a solution containing both mitotane and other analytes. The detection limits of the analytes for the reverse polarity sweeping-dispersive liquid–liquid microextraction method were found to be in the range of 1.5–3 ng/mL, which were approximately 1000 times lower than in the conventional hydrodynamic injection (5 s, 0.5 psi) without any preconcentration procedure. All analytes were completely resolved in less than 13 min by uncoated silica capillary with an inner diameter of 75 μm (ID) × 60 cm. Electrophoretic separation was performed in reverse polarity with a voltage of –25 kV with a background electrolyte (BGE) consisting of 100 mM SDS, 25% ACN, 25 mM phosphate buffer (pH 2.5), and 7 mM β-cyclodextrin. 相似文献
105.
Fijalkowski KJ Genova RV Filinchuk Y Budzianowski A Derzsi M Jaroń T Leszczyński PJ Grochala W 《Dalton transactions (Cambridge, England : 2003)》2011,40(17):4407-4413
We describe the successful synthesis of the first mixed-cation (pseudoternary) amidoborane, Na[Li(NH(2)BH(3))(2)], with theoretical hydrogen capacity of 11.1 wt%. Na[Li(NH(2)BH(3))(2)] crystallizes triclinic (P1) with a = 5.0197(4) ?, b = 7.1203(7) ?, c = 8.9198(9) ?, α = 103.003(6)°, β = 102.200(5)°, γ = 103.575(5)°, and V = 289.98(5) ?(3) (Z = 2), as additionally confirmed by Density Functional Theory calculations. Its crystal structure is topologically different from those of its orthorhombic LiNH(2)BH(3) and NaNH(2)BH(3) constituents, with distinctly different coordination spheres of Li (3 N atoms and 1 hydride anion) and Na (6 hydride anions). Na[Li(NH(2)BH(3))(2)], which may be viewed as a product of a Lewis acid (LiNH(2)BH(3))/Lewis base (NaNH(2)BH(3)) reaction, is an important candidate for a novel lightweight hydrogen storage material. The title material decomposes at low temperature (with onset at 75 °C, 6.0% mass loss up to 110 °C, and an additional 3.0% up to 200 °C) while evolving hydrogen contaminated with ammonia. 相似文献
106.
Car-Parrinello and path integrals molecular dynamics (CPMD and PIMD) simulations were carried out for the 10π-electron aromatic systems: 2-hydroxy-2,4,6-cycloheptatrien-1-one, commonly known as Tropolone (I) and 2-hydroxy-2,4,6-cycloheptatriene-1-thione, called Thiotropolone (II) in vacuo and in the solid state. The extremely fast proton transfer (FPT) and “prototropy” tautomerism in the keto-enol (thione-enethiol) systems have been analyzed on the basis of CPMD and PIMD methods level. Comparisons of two-dimensional (2D) free-energy landscapes of reaction coordinate δ-parameter and RO…O or RO…S distances shows that the OH… tautomer to be more favorable in the Thiotropolone. The hydrogen between the oxygen and the sulfur atoms adopts a starkly asymmetrical position in the double potential well. The values of the energy barriers for the FPT were calculated and suggested a strong hydrogen bond with low barrier for FPT mechanism. These studies and the 2D average index of π-delocalization 〈λ〉 landscape of time evolutions of RO1…O2 and RC7O2 or RC7S1 distances for the both crystals indicate that hydrogen bonds in the crystals of Tropolone (I) and Thiotropolone (II) have characteristic properties for the type of bonding model resonance-assisted hydrogen bonds and also low-barrier hydrogen bonds. In the crystal of the Thiotropolone (II), we found the hydrogen bond O H…S existing without the equilibrium of the two tautomers whereas in the crystal of the Tropolone (I) has been confirmed the hydrogen bond O H…O existing with the equilibrium of the two tautomers. It was also found the significant differences in frequency, speed, and the image of the FPT in the studied crystals. © 2018 Wiley Periodicals, Inc. 相似文献
107.
The objective of this article was to design the selective molecularly imprinted sorbent dedicated to the solid‐phase extraction of S‐pramipexole from the complex matrix such as human urine. For that purpose, S‐2,6‐diamino‐4,5,6,7‐tetrahydrobenzothiazole was used as the template acting as the structural analog of S‐pramipexole and five various monomers were employed in the presence of ethylene glycol dimethacrylate to produce molecularly imprinted polymers. The binding capabilities of resulted polymers revealed that the highest imprinting effect was noted for polymer prepared from the itaconic acid. The comprehensive analysis of morphology and the characterization of binding sites showed not only negligible differences in the extension of surfaces of imprinted and nonimprinted polymers but also higher heterogeneity of binding sites in the imprinted material. Comprehensive optimization of the molecularly imprinted solid‐phase extraction allowed to select the most appropriate solvents for loading, washing, and elution steps. Subsequent optimization of mass of sorbent and volumes of solvents allowed to achieve satisfactory total recoveries of S‐pramipexole from the model multicomponent real sample of human urine that equals to 91.8 ± 3.2% for imprinted sorbent with comparison to only 37.1 ± 1.1% for Oasis MCX. 相似文献
108.
The Fukui functions based on the computable local polarizability vector have been presented for a group of simple molecules. The necessary approximation for the density functional theory softness kernel has been supported by a theoretical analysis unifying and generalizing early concepts produced by the several authors. The exact relation between local polarizability vector and the derivative of the nonlocal part of the electronic potential over the electric field has been demonstrated. The resulting Fukui functions are unique and represent a reasonable refinement when compared to the classical ones that are calculated as the finite difference of the density in molecular ions. The new Fukui functions are strongly validated by their direct link to electron dipole polarizabilities that are reported experimentally and by other computational methods. 相似文献
109.
This review describes the state of the art in the field of polyoxometalates containing noble metal atoms (ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold). The structures of the various species are listed together with their applications (mainly in catalysis). 相似文献
110.
Summary Single reverse water-gas shift (RWGS) and dehydrogenation of propane with CO2(DH-CO2) reactions in the presence and absence of the CrOx/SiO2 catalyst have been studied between 673 and 873 K. It was found that the CrOx/SiO2 catalyst is active both in the dehydrogenation of propane and in the RWGS reactions. The obtained results suggest that the
dehydrogenation of propane to propene in the presence of CO2on CrOx/SiO2can be facilitated by the RWGS reaction.</o:p> 相似文献