Separation and identification of compounds in Adinandra nitida by comprehensive two-dimensional liquid chromatography coupled to atmospheric pressure chemical ionization source ion trap tandem mass spectrometry

A comprehensive two-dimensional liquid chromatographic (2D-LC) separation system based on the combination of a CN column and a Merck Chromolith Flash reversed-phase column was developed for the separation of components in Adinandra nitida, one type of traditional Chinese medicine (TCM). The two dimensions were connected by a ten-port, dual-position valve controlled automatically by software written in-house. The effluents were detected by both ultraviolet and atmospheric pressure chemical ionization source ion trap tandem mass spectrometry (MS). The calculated peak capacity of the 2D-LC–MS/MS system was above 1240. More than 57 components were resolved in the methanol extract from Adinandra nitida leaves, and five of these were identified based on their relative retention times, molecular weights and MS/MS spectra.     

The Inhibition of Gastric Cancer Cells’ Progression by 23,24-Dihydrocucurbitacin E through Disruption of the Ras/Raf/ERK/MMP9 Signaling Pathway

Gastric cancer is considered to be one of the most common causes of cancer death worldwide due to its high recurrence and metastasis rates. The molecule 23,24-Dihydrocucurbitacin E (DHCE) is a cucurbitacin-derived tetracyclic triterpenoid compound that has anti-tumor activity, but the exact mechanism remains to be elucidated. This research aimed to explore the effects of DHCE on human gastric cancer cells and the possible mechanisms. The results showed that DHCE suppressed proliferation, migration, and invasion of gastric cancer cells, as well as induced apoptosis and G2/M phase arrest. Mechanistically, the potential targets and pathways of DHCE were predicted using database screening and verified using a molecular docking study, fluorescence staining, and Western blot. The results indicated that DHCE obviously inhibited the kinase activity of ERK2 via targeting its ATP-binding domain, destroyed F-actin microfilament, and reduced the expression levels of Ras, p-c-Raf, ERK, p-ERK, and MMP9 proteins. Collectively, our study demonstrated that DHCE suppressed gastric cancer cells’ proliferation, migration, and invasion through targeting ERK2 and disrupting the Ras/Raf/ERK/MMP9 signaling pathway. These properties make DHCE a promising candidate drug for the further design and development of novel and effective Ras/Raf/ERK/MMP9 pathway inhibitors for treating gastric cancer.     

Starburst triarylamine based dyes for efficient dye-sensitized solar cells

We report here on the synthesis and photophysical/electrochemical properties of a series of novel starburst triarylamine-based organic dyes (S1, S2, S3, and S4) as well as their application in dye-sensitized nanocrystalline TiO2 solar cells (DSSCs). For the four designed dyes, the starburst triarylamine group and the cyanoacetic acid take the role of electron donor and electron acceptor, respectively. It was found that the introduction of starburst triarylamine group to form the D-D-pi-A configuration brought about superior performance over the simple D-pi-A configuration, in terms of bathochromically extended absorption spectra, enhanced molar extinction coefficients and better thermo-stability. Moreover, the HOMO and LUMO energy levels tuning can be conveniently accomplished by alternating the donor moiety, which was confirmed by electrochemical measurements and theoretical calculations. The DSSCs based on the dye S4 showed the best photovoltaic performance: a maximum monochromatic incident photon-to-current conversion efficiency (IPCE) of 85%, a short-circuit photocurrent density (J(sc)) of 13.8 mA cm(-2), an open-circuit photovoltage (V(oc)) of 0.63 V, and a fill factor (ff) of 0.69, corresponding to an overall conversion efficiency of 6.02% under 100 mW cm(-2) irradiation. This work suggests that the dyes based on starburst triphenylamine donor are promising candidates for improvement of the performance of the DSSCs.     

Differentiation of Resina Draconis from Sanguis Draconis by CE

A simple, accurate method based on capillary electrophoresis with electrochemical detection (CE–ED) has been developed to determine loureirin A, loureirin B and dracorhodin for differentiation of Resina Draconis from Sanguis Draconis. The effects of some important factors such as acidity and concentration of running buffer, separation voltage, injection time, and applied potential on the CE–ED working electrode were investigated. Under the optimum conditions, the three analytes could be well separated within 30 min in a 75 cm capillary at a separation voltage of 14 kV in a 80 mmol L^?1 borate buffer (pH 9.24). The working electrode was a 300-μm-diameter carbon disc electrode positioned opposite the outlet of the capillary in a wall-jet configuration and was set at a potential of 0.90 V (vs. SCE). Excellent linearity was established over two orders of magnitude with detection limits (S/N = 3) ranging from 3 × 10^?7 g mL^?1 to 1 × 10^?6 g mL^?1 for all three analytes. The relative standard deviations of peak current and migration times of loureirin A, loureirin B and dracorhodin were 2.1, 1.7, 4.4 and 2.9, 2.8, 3.3% (n = 5), respectively. The recoveries of three constituents ranged from 98.8 to 101.8%. The methodology has been successfully applied to analyze and differentiate the actual samples with satisfactory assay results.     

Solid-state MAS NMR studies of Brønsted acid sites in zeolite H-Mordenite

(17)O-(1)H double resonance NMR spectroscopy was used to study the local structure of zeolite H-Mordenite. Different contact times were used in cross-polarization magic angle spinning (CPMAS) NMR, CP rotational-echo double resonance (CP-REDOR) NMR, and heteronuclear correlation (HETCOR) NMR spectroscopy to distinguish between Br?nsted acid sites with different O-H distances. The accessibility of the various Br?nsted acid sites was quantified by adsorbing the basic probe molecule trimethylphosphine in known amounts. On the basis of these experiments, locations of different Br?nsted acid sites in H-Mordenite (H-MOR) were proposed. The use of (17)O chemical shift correlations to help assign sites is discussed.     

Enhanced indirect fluorescence detection of p-nitrophenol, 2,4-dinitrophenol and trinitrophenol by micellar electrokinetic capillary chromatography with in-column optical-fiber LED-induced fluorescence detection

Enhanced indirect fluorescence detection with in-column optical-fiber LED-induced fluorescence (LED-IF) detection has been developed for the simultaneous separation and determination of p-nitrophenol, 2,4-dinitrophenol and trinitrophenol. The instrumental set-up is simple, cost-effective and the detection method is stable. Different experimental parameters have been studied. The optimum conditions were determined as: running buffer (pH 9.1) composed of 10 mM borate, 80 mM sodium dodecylsulfate and 0.18 μM fluorescein (as a background reagent); applied voltage of 15 kV; working temperature of 25.0 °C. The limits of detection (S/N = 3) were 11, 18 and 16 μM for p-nitrophenol, 2,4-dinitrophenol and trinitrophenol, respectively. The nitrophenols were completely separated in 13 min and the number of theoretical plates for p-nitrophenol, 2,4-dinitrophenol and trinitrophenol were 8.1 × 10(6), 6.5 × 10(6) and 8.4 × 10(6), respectively. The RSDs (n = 6) for the migration time and the peak area were better than 0.85 and 0.91%, respectively. Our proposed method possesses the advantages of rapidness and good separation efficiency.     

Unique Thia‐Baeyer–Villiger‐Type Oxidation of Dibenzothiophene Sulfoxides Derivatives

The present research has demonstrated that selective C?S bond cleavages of dibenzothiophene and its derivatives are feasible by thia‐Baeyer–Villiger type oxidation, i. e. the oxygen insertion process within a sulfoxide‐carbon linkage, in the presence of porphyrin iron (III) and by ultraviolet irradiation originating from sunlight, high pressure Hg‐lamp or residentially germicidal ultraviolet lamp under very mild conditions. This reaction with tert‐butylhydroperoxide at 30.0 °C leads to dibenzo[1,2]oxathiin‐6‐oxide ( PBS ) in 83.2 % isolated yield or its hydrated products, 2‐(2‐hydroxyphenyl)‐benzenesulfinic derivatives ( HPBS ) in near 100 % yield based HPLC data. PBS and HPBS are a type of biological products detected on the C?S bond cleavage step through various oxidative biodesulfurization ( OBDS ) pathways, and are useful synthetic intermediates and fine chemicals. These observations may contribute on understanding delicately molecular aspect of OBDS in the photosynthesis system, expanding the C‐S cleavage chemistry of S‐heterocyclic compounds and approaching toward biomemic desulfurization with respect to converting sulfur contaminants to chemically beneficial blocks as needed and performing under the ambient conditions.     

Highly efficient non-doped blue fluorescent OLEDs with low efficiency roll-off based on hybridized local and charge transfer excited state emitters

Designing a donor–acceptor (D–A) molecule with a hybridized local and charge transfer (HLCT) excited state is a very effective strategy for producing an organic light-emitting diode (OLED) with a high exciton utilization efficiency and external quantum efficiency. Herein, a novel twisting D–π–A fluorescent molecule (triphenylamine–anthracene–phenanthroimidazole; TPAAnPI) is designed and synthesized. The excited state properties of the TPAAnPI investigated through photophysical experiments and density functional theory (DFT) analysis reveal that its fluorescence is due to the HLCT excited state. The optimized non-doped blue OLED using TPAAnPI as a light-emitting layer exhibits a novel blue emission with an electroluminescence (EL) peak at 470 nm, corresponding to the Commission International de L''Eclairage (CIE) coordinates of (0.15, 0.22). A fabricated device termed Device II exhibits a maximum current efficiency of 18.09 cd A⁻¹, power efficiency of 12.35 lm W⁻¹, luminescence of ≈29 900 cd cm⁻², and external quantum efficiency (EQE) of 11.47%, corresponding to a high exciton utilization efficiency of 91%. Its EQE remains as high as 9.70% at a luminescence of 1000 cd m⁻² with a low efficiency roll-off of 15%. These results are among the best for HLCT blue-emitting materials involved in non-doped blue fluorescent OLEDs. The performance of Device II highlights a great industrial application potential for the TPAAnPI molecule.

A new pure fluorescent blue HLCT-emitter was designed and synthesized. Highly efficient non-doped blue OLEDs with low efficiency roll-off were achieved.     

Bi2S3 nanomaterials: morphology manipulation and related properties

The Bi(2)S(3) nanomaterials with various morphologies such as nanorods, nanowires, nanowire bundles, urchin-like microspheres and urchin-like microspheres with cavities have been successfully synthesized through a simple hydrothermal method. Experimental results indicate that sulfur sources play crucial roles in determining the morphologies of Bi(2)S(3) products. Moreover, formation mechanisms of different Bi(2)S(3) nanostructures are discussed based on understanding of the growth habit of Bi(2)S(3) crystal. Finally, we also studied the morphologies-dependent electrochemical and optical properties of the as-synthesized Bi(2)S(3) nanomaterials.     

Design,Synthesis, and Evaluation of Novel L-Pyroglutamic Acid Derivatives as Potent Antifungal Agents

Chemistry of Natural Compounds - A series of novel L-pyroglutamate containing 1,2,3-triazole ring substructures was synthesized and characterized by adopting an appropriate synthetic scheme. The...