Tupisteroide A–C,three new polyhydroxylated steroidal constituents from the roots of Tupistra chinensis

Three new steroidal compounds with polyhydroxy groups, tupisteroide A–C (1–3), were obtained from the roots of Tupistra chinensis, together with one known compound (4) that was isolated from this plant for the first time. The structures of tupisteroide A–C were determined on the basis of one‐ and two‐dimensional NMR spectroscopy, including ¹H–¹H Correlation Spectroscopy, Heteronuclear Multiple Bond Correlation, and Heteronuclear Single Quantum Coherence experiments. The isolated compounds were evaluated for their cytotoxic activities against A549, HepG2, and CaSki cancer cell lines in vitro. Among them, compounds 1, 2, and 4 did not show significant inhibitory activity, but compound 3 showed cytotoxicity against A549 cancer cell lines with IC₅₀ values of 25.0 μM. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis and characterization of polymethacrylates containing conjugated oligo(phenylene ethynylene)s as side chains

In order to form suitable systems designed for resonance energy transfer, a series of monodisperse methacrylate‐based monomers containing rigid π‐conjugated oligo(phenylene ethynylenes) with different sizes of the conjugated systems ( M1 – M3 ), and therefore different optoelectronic properties, were synthesized and subsequently polymerized using the reversible addition–fragmentation chain transfer polymerization technique ( P1 – P3 ). In addition, these oligomers were also copolymerized with methyl methacrylate. The obtained polymers were characterized by ¹H NMR spectroscopy, size exclusion chromatography, and analytical ultracentrifugation. The photophysical properties of the polymers were studied by UV–vis absorption and emission spectroscopy in diluted solutions as well as in thin films and compared to the photophysics of the corresponding monomers. Thereby, changes going from monomeric to polymeric systems could be detected in fluorescence quantum yields and lifetimes pointing to energy trapping, e.g., energy transfer. Donor–acceptor copolymers containing different numbers of monomeric units within the side chain exhibit differences in the emission spectra, indicating that energy trapping in polymers is very sensitive to structural properties such as the chain length. UV–vis absorption spectroscopy as well as time‐resolved lifetime studies indicate intrapolymer and interpolymer energy transfer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Development and validation of UPLC‐MS/MS method for determination of domperidone in human plasma and its pharmacokinetic application

A sensitive, rapid and selective ultra‐performance liquid chromatography–tandem mass spectrometric (UPLC‐MS/MS) method was developed for the determination and pharmacokinetic study of domperidone in human plasma. Diphenhydramine was used as the internal standard. Plasma sample pretreatment involved a one‐step liquid–liquid extraction with a mixture of diethyl ether–dichloromethane (3:2, v/v). The analysis was carried out on an Acquity UPLC^TM BEH C₁₈ column. The mobile phase consisted of methanol–water containing 10 mmol/L ammonium acetate and 0.5% (v/v) formic acid (60:40, v/v). The detection was performed on a triple quadrupole tandem mass spectrometer in multiple reaction monitoring mode via electrospray ionizationsource with positive mode. Each plasma sample was chromatographed within 2.1 min. The standard curves for domperidone were linear (r² ≥ 0.99) over the concentration range of 0.030–31.5 ng/mL with a lower limit of quantification of 0.030 ng/mL. The intra‐ and inter‐day precision (relative standard deviation) values were not higher than 13% and accuracy (relative error) was from ?7.6 to 1.2% at three quality control levels. The method herein described was superior to previous methods and was successfully applied to the pharmacokinetic study of domperidone in healthy Chinese volunteers after oral administration. Copyright © 2012 John Wiley & Sons, Ltd.     

Zero-valent iron particles embedded on the mesoporous silica–carbon for chromium (VI) removal from aqueous solution

Journal of Nanoparticle Research - The demand for metal nanoparticles is increasing strongly. Transferred arc synthesis is a promising process in this respect, as it shows high production rates,...     

Enhancement of thermal stability and photoluminescent performance of blue light emitting material by incorporating adamantane moieties into carbazole system

A facile route to improve photoluminescent performance and service lifetime of a promising blue light emitting material is reported and demonstrated here using a copolymer system of N-(2-ethylhexyl)-2,7-carbazole (Cz) and 1,3,5,7-tetrakis- (4-bromophenyl) adamantane (TBA). The copolymers were successfully synthesized by palladium-catalyzed Suzuki coupling reactions. Structure and molecular weight of the materials were characterized by FT-IR and ¹H-NMR spectroscopies, elemental analysis and gel permeation chromatography. The influence of adamantane content on the thermal stability and photoluminescent performance of the synthesized copolymers was investigated in detail. DSC results showed that glass transition temperature increased dramatically, from 68°C for neat carbazole, to 88°C, 120°C and 152°C, after the addition of 10%, 20%, and 30% TBA, respectively. The same trend was found when thermal decomposition temperature at 5% weight loss was evaluated from TGA data. Importantly, this increased stability can be extended to thermo-optical performance, with the Cz-TBA system showing higher color purity and stronger emission intensity within blue light wavelength than carbazole alone. Nevertheless, measurements of emitting spectral stability at a broader temperature range (100–200°C) and photoluminescence quantum yield suggested that there is a delicate trade-off between the performance and adamantane content.