A combination of periodic acid or oxone® and a catalytic amount of KBr in the presence of few drops of water, were used for the catalytic oxidation of urazoles and bis-urazoles to their corresponding triazolinediones under mild and heterogeneous conditions with moderate to excellent yields. 相似文献
Characterizing and controlling the interlayer orientations and stacking orders of two‐dimensional (2D) bilayer crystals and van der Waals (vdW) heterostructures is crucial to optimize their electrical and optoelectronic properties. The four polymorphs of layered gallium selenide (GaSe) crystals that result from different layer stackings provide an ideal platform to study the stacking configurations in 2D bilayer crystals. Through a controllable vapor‐phase deposition method, bilayer GaSe crystals were selectively grown and their two preferred 0° or 60° interlayer rotations were investigated. The commensurate stacking configurations (AA′ and AB stacking) in as‐grown bilayer GaSe crystals are clearly observed at the atomic scale, and the Ga‐terminated edge structure was identified using scanning transmission electron microscopy. Theoretical analysis reveals that the energies of the interlayer coupling are responsible for the preferred orientations among the bilayer GaSe crystals. 相似文献
The authors describe an efficient method for microextraction and preconcentration of trace quantities of cationic nitrogen compounds, specifically of anilines. It relies on a combination of electrochemically controlled solid-phase microextraction and on-line in-tube solid-phase microextraction (SPME) using polypyrrole-coated capillaries. Nanostructured polypyrrole was electrically deposited on the inner surface of a stainless steel tube and used as the extraction phase. It also acts as a polypyrrole electrode that was used as a cation exchanger, and a platinum electrode that was used as the anode. The solution to be extracted is passed over the inner surface of the polypyrrole electrode, upon which cations are extracted by applying a negative potential under flow conditions. This method represents an ideal technique for SPME of protonated anilines because it is fast, easily automated, solvent-free, and inexpensive. Under optimal conditions, the limits of detection are in the 0.10–0.30 μg L‾1 range. The method works in the 0.10 to 300 μg L‾1 concentration range. The inter- and intra-assay precisions (RSD%; for n = 3) range from 5.1 to 7.5 % and from 4.7 to 6.0 % at the concentration levels of 2, 10 and 20 μg L‾1, respectively. The EC-in-tube SPME method was successfully applied to the analysis of methyl-, 4-chloro-, 3-chloro and 3,4-dichloroanilines in (spiked) water samples.
New derivatives of triazole‐isoxazole were synthesized through a four‐step reaction starting from various ethyl 4‐aryl‐2,4‐dioxobutanoate derivatives. Finally, all compounds were examined by MTT assays for cytotoxic activity in two human breast cancer cell lines (MCF‐7 and T‐47D). 相似文献
Reaction of 2‐amino‐N‐substituted benzamides and dimethyl acetylenedicarboxylate (DMAD) in the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) in H2O at room temperature led to the formation of novel 1,2,3,4‐tetrahydroquinazolinones. 相似文献
Molecular dynamics simulations and umbrella sampling have been used to investigate the sliding of distamycin anticancer drug along the DNA minor groove. The potential energy surface calculated for the sliding of drug shows three minima. The global minimum corresponds to the binding of drug to the AT-rich region, which is the origin of sequence selectivity of distamycin. This selectivity originates from both structural factors and energy contributions. The analysis of energy contributions of binding was performed by the MM–PBSA method. The analysis of hydrogen bonds and van der Waals, electrostatic, and solvation interactions show that structural or steric factors are more important in the selectivity of distamycin than energetic factors. The results of this study can be applied in the design of new derivatives of distamycin anticancer drug with improved properties. 相似文献
A novel synthesis of thioxo-quinazolino[3,4-a]quinazolinone framework was developed through a four-step reaction starting from isatoic anhydride. The resulting 2-aminobenzamides from the reaction of isatoic anhydride and different amines underwent coupling–cyclization reaction with 2-nitrobenzaldehydes, reduction of nitro group, and then cyclization reaction with carbon disulfide (CS2). All steps were carried out under easy and user-friendly conditions in a short time without using expensive catalysts or reagents.
[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献