This paper reports the synthesis of a perylene-bridged bis(crown ether) through the condensation reaction between primary amine-armed dibenzo-24-crown-8 and 3,4,9,10-perylenetetracarboxylic dianhydride. Pseudorotaxane with a perylene moiety at the wheel and a fullerene unit in the middle of the axle was prepared, which was evidenced by 1H NMR and fluorescence experiments. Subsequent investigations show that the formation and disassociation of the pseudorotaxane can be controlled by the alternating addition of KPF6 and 18-crown-6, following the change of the florescence intensity of perylene.
A novel amphiphilic silica‐based monolithic column having surface‐bound octanoyl‐aminopropyl moieties was successfully prepared by a one‐step in situ derivatization process. As expected, the amphiphilic monolithic column exhibited RP chromatographic behavior toward non‐polar solutes (e.g., alkyl benzenes) with high column performance. As the pH of the buffer inside the column increases, the EOF changed from −2.65×10−8m2 V−1s−1 at pH 3.0 to 1.20×10−8 m2 V−1s−1 at pH 8.0 with the reversion of EOF at about pH 6.4. Using acidic mobile phase, five aromatic acids can be efficiently separated in less than 6 min under co‐EOF conditions. For basic compounds, symmetrical peaks were obtained due to the existence of hydrophilic acyl amide group, which can effectively minimize the adsorption of the positively charged basic analyte to the silica‐based surface of the capillary column. 相似文献
A novel magnetic solid-phase extraction (MSPE) sorbent, magnetite/silica/poly (methacrylic acid–co-ethylene glycol dimethacrylate) (Fe3O4/SiO2/P(MAA-co-EGDMA)), was developed. This MSPE material was prepared by distillation–precipitation polymerization of MAA and EGDMA in the presence of Fe3O4/SiO2 microspheres with the surface containing abundant reactive double bonds. The resultant sorbent material was characterized by elemental analysis, electron microscopy, X-ray diffraction and Fourier-transformed infrared spectroscopy. In this work, eleven sulfonamides (SAs) were selected as model analytes to validate the extraction performance of this new MSPE sorbent. Noticeably, the extraction can be carried out quickly, the extraction time for the SAs onto Fe3O4/SiO2/P(MAA-co-EGDMA) sorbent can be clearly shortened to 0.5 min. The desorption solution of SAs was analyzed by LC–MS/MS, and the results showed that the recoveries of these compounds were in the range of 87.6–115.6%, with relative standard deviations ranging between 0.9% and 10.8%; the limit of detection were in the range of 0.5–49.5 ng/L. 相似文献
We impregnated Rayon-based activated carbon fibers (ACFs) by p-aminobenzoic acid (PABA) and systematically investigated their porous structure, surface chemistry, and formaldehyde removal
behavior. Using standard nitrogen adsorption analysis, we found that the specific surface area, the micropore volume, and
the total pore volume decreased with increasing concentration of PABA. Through elemental analysis and X-ray photoelectron
spectroscopy, it was found that some nitrogen-containing functional groups presented on the surface of modified Rayon ACFs.
The modified Rayon-based ACFs showed much higher adsorption capacity and longer breakthrough time for formaldehyde than did
as-prepared Rayon-based ACF. We proposed that the improvement of formaldehyde removal by modified ACFs was attributed to the
combined effects of physisorption contributed by pore structures and chemisorption contributed by the N-containing functional
groups, whereas there was only physisorption between the as-prepared ACF and formaldehyde molecules. 相似文献
Polypyrrole (PPy)-cellulose composites were prepared by in situ polymerization of pyrrole in pulp suspension using ferric
chloride as an oxidant. Some sulfonic compounds including p-toluenesulfonic acid and its sodium salt (PTSA and PTSA-Na), benzenesulfonic acid (BSA), dodecylbenzene sulfonic acid and
its sodium salt (DBSA and DBSA-Na), 2-naphthalene sulfonic acid (NSA) and 9,10-anthraquinone-2-sulfonic acid sodium salt (AQSA-Na)
were used as dopants, and their effect on the conductivity of PPy-cellulose composite was investigated. The results showed
that the species and dose of dopants had significant effect on the surface resistivity and environmental stability of PPy-cellulose
composite. As the dopant, PTSA and DBSA had a superior doping effect compared to their sodium salts. The doping result of
BSA was close to that of PTSA. NSA bearing a naphthalene ring and AQSA-Na bearing an anthraquinone ring gave the best conductivity.
Using NSA or AQSA-Na as a dopant, along with suitable polymerization conditions, the PPy-cellulose composite obtained showed
a surface resistivity as low as 20 Ω cm−2. For most dopants, the lowest surface resistivity could be obtained when the molar ratio of dopant to pyrrole was 1:1. Both
ATR-FTIR (attenuated total reflection-Fourier transform infrared spectroscopy) and XPS (X-ray photoelectron spectroscopy)
analysis confirmed that the PPy on pulp fibers doped with PTSA, PTSA-Na, NSA and AQSA-Na had different doping levels. The
higher doping level of the PPy in the composites doped with NAS and AQSA-Na might be related to the stronger interaction of
cellulose with PPy chains. Both SEM (scanning electron microscopy) and AFM (atomic force microscopy) observation revealed
the fine grain microstructure of the PPy on the composites with average grain sizes in the range of 100–200 nm, and the PPy
on the samples doped with NSA and AQSA-Na exhibited quite different morphology as compared to those doped with PTSA and its
sodium salt. 相似文献
Zofenoprilat is an active metabolite of zofenopril, which is very unstable in plasma because of oxidative degradation of its thiol group. In this method, p-bromophenacyl bromide was used as derivatization reagent, immediately after plasma separation, to react with the free thiol group of zofenoprilat and form the derivative zofenoprilat-p-BPB. After acidification with 50% acetic acid, the derivatized plasma samples were extracted with methyl tert-butyl ether and separated on a C18 column with 40:60 (v/v) 10 mM ammonium acetate buffer solution containing 0.1% formic acid–acetonitrile as mobile phase. Calibration plots were linear over the concentration range 1–500 ng mL−1 for zofenopril and 2–1,800 ng mL−1 for zofenoprilat. The method was successfully used to study the bioavailability of zofenopril calcium capsules relative to that of zofenopril calcium tablets in healthy Chinese volunteers.
Amphiphilic silica nanoparticles surface-functionalized by 3-aminopropyltriethoxysilane (APTES) and octyltriethoxylsilane (OTES) were successfully prepared and characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR) and thermogravimetry (TG) techniques. The potential use of these bifunctionalized nanoparticles as pseudostationary phases (PSPs) in capillary electrophoresis (CE) for the separation of charged and neutral compounds was evaluated in terms of their suitability. As expected, fast separation of representative aromatic acids was fulfilled with high separation efficiency, because they migrate in the same direction with the electroosmotic flow (EOF) under optimum experimental conditions. Using a buffer solution of 30mmol/L phosphate (pH 3.0) in the presence of 0.5mg/mL of the synthesized bifunctionalized nanoparticles, the investigated basic compounds were baseline-resolved with symmetrical peaks. Due to the existence of amino groups on the surface of nanoparticles, "silanol effect" that occurs between positively charged basic analytes and the silanols on the inner surface of capillary was greatly suppressed. Furthermore, the separation systems also exhibited reversed-phase (RP) behavior when neutral analytes were tested. 相似文献