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Brazilein is among the main chemical constituents of

A new xanthone, 1,7-dihydroxy-2,3,5,6-tetramethoxyxanthone (1), together with eight known compounds including one xanthone (2) and seven isoflavones (3-9) has been isolated from the leaves of Millettia pachyloba. This is the first report on the isolation of xanthone from the genus Millettia. The structure of the compound 1 was elucidated on the basis of spectroscopic data interpretation, including 1D and 2D NMR and HREIMS. Compound 1 exhibited weak cytotoxicity against five human cancer cell lines, HL-60, SMMC-7721, A-549, MCF-7 and SW480.

The dissociative ionization processes of the methanol monocation CH3OH+ to H3+ + CHO and H2O+ + CH2 are studied by ab initio method, and hydrogen migration processes are confirmed in these two dissociation processes. Due to the positive charge assignment in dissociation processes, the fragmentation pathways of CH3OH+ to H3 + CHO+ and CH3OH+ to H2O + CH2+ are also calculated. The calculation results show that a neutral H2 moiety in the methanol monocation CH3OH+ is the origin of the formation of H3+, and the ejection of fragment ions H3+ and H2O+ is more difficult than CHO+ and CH2+ respectively. Experimentally, by using a dc-slice imaging technique under an 800 nm femtosecond laser field, the velocity distributions of fragment ions H3+, CHO+, CH2+, and H2O+ are calculated from their corresponding sliced images. The presence of low-velocity components of these four fragment ions confirms that the formation of these ions is not from the Coulomb explosion of the methanol dication. Hence, the four hydrogen migration pathways from the methanol monocation CH3OH+ to H3+ + CHO, CHO+ + H3, H2O+ + CH2, and CH2+ + H2O are securely confirmed. It can be observed in the time-of-flight mass spectrum of ionization and dissociation of methanol that the ion yields of fragment ions H3+ and H2O+ are lower than CHO+ and CH2+ respectively, which is consistent with the theoretical results according to which dissociation from the methanol monocation to H3+ and H2O+ is more difficult than CHO+ and CH2+ respectively.

It is a challenge for many researchers to separate volatile compounds. In this study, we introduce a rapid and efficient method of separating target compound from the twigs of

Countercurrent separation (CCS) has been widely used for the separation of high abundance compounds. However, the identification of low abundance compounds, such as mammalian steroid hormones, from natural sources is still a challenging task. A mixture of 14 human steroid hormone reference compounds was prepared for the development of a CCS enrichment strategy. The TLC-based GUESS (Generally Useful Estimate of Solvent Systems) method along with partitioning experiments were implemented to develop a process for the enrichment of these low abundance compounds with CCS. The application of CCS to the steroid hormone enrichment of Vitex negundo extracts was demonstrated by the identification of progesterone and estriol. This method provides a CCS-driven strategy to mine plant sources for low abundance compounds.

An interesting evolution to prepare shape-controlled Cu 2 O nanocrystals was realized by a convenient one pot synthesis. The Cu 2 O nanocrystals with different shapes can be obtained simply by adjusting the composition of reaction system. And, a plausible mechanism was also proposed to explain the nanostructures formation. The surface of Cu 2 O spheres with thorn exhibited high photocatalytic activity on the degradation of methyl orange (MO) solution under visible light irradiation. The photodegradation efficiency of MO solution reach up to 99.67% at the first 10 min. It is still as high as 98% even at the end of the fourth cycle.

The dissociative ionization processes of the methanol monocation CH

Well-defined cuprous oxides (Cu2O) with different morphologies were successfully deposited on fluorine-doped tin oxide (FTO)-covered glass substrates by potentiostatic deposition. The effect of the pH values on the crystal morphologies of Cu2O was studied. The as-prepared products were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and UV-visible spectroscopy. The typical XRD patterns revealed that all Cu2O thin films were pure Cu2O phase. Different crystal morphologies of Cu2O could be obtained by varying pH. The Cu2O thin film was composed of a large number of star-like shape grains with the pH of 4.8. With a further increase of the pH, the Cu2O film showed the uniform dendrite morphology. LSV uncovered that E R (reduction potential of Cu2+ to Cu+) increased with the pH value enlargement. According to the EIS, diffusion coefficient of Cu2+ ion was reduced with the increase of the pH. The UV-vis absorption spectra revealed that the broad absorption peaks were from 300 to 500 nm and the evaluated band gap of the films was tunable in the range of 2.02–2.67 eV, with the variation of the pH values. According to the experiment and relevant literatures, the probable electrodeposition mechanism of the Cu2O was discussed.

In this work, Cu2ZnSnS4 (CZTS) nanoworm films have been directly deposited on fluorine-doped tin oxide (FTO) conductive glass substrates by a solvothermal method using polyethylene glycol 400 (PEG-400) as the solvent and structure-directing agent. The as-obtained CZTS thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectrum (XPS), UV–vis spectra and photoelectrochemical measurement. The synthetic conditions, such as reaction temperature, reaction time, solvents, were investigated to know the formation of CZTS thin films. The results showed that PEG-400 plays a key role in the formation of the nanoworms by affecting the crystal growth process. The p-type CZTS nanoworm film with the band gap of 1.62 eV was synthesized at 180 °C for 22 h and the photovoltaic performance was studied by forming a photoelectrochemical cell.

CuInS 2 thin films were deposited with fix different thiourea (TU) concentrations on fluorine-doped tin oxide-coated (FTO) conductive glass substrates by a facile and rapid solvothermal method. XRD analysis shows that all CuInS 2 thin films crystallize in a chalcopyrite structure with a preferential orientation along (112) direction, and the average crystallize sizes of the nanoparticles are 20–50 nm. The X-ray photoelectron spectroscopy (XPS) shows that the S deficiency decreases with increasing TU concentration. Surface morphology studies show the CuInS 2 thin films are composed of nanoplates or sphere-like. The thicknesses of the CuInS 2 thin films can be adjusted from 0.33 to 2.1 μm by controlling the TU concentration. The average absorption of all CuInS 2 thin films is greater than 90% in the wavelength ranging from 400 to 950 nm, and the band gaps of all CuInS 2 thin films are in the range of 1.52–1.90 eV. As shown in room temperature photoluminescence (PL), the as-synthesized CuInS 2 thin films have a near-infrared emission at 1.54 eV and an orange–red emission at 1.92 eV in visible spectrum.

TLC-based strategies were proposed in 1979 (Hostettmann et al.) and 2005 (Friesen & Pauli; GUESS method) to minimize the number of partitioning experiments required for countercurrent separation (CCS) solvent system selection. As semi-empirical approaches, both proposed that the K values defining the sweet spot of optimal CCS corresponded to a matching Rf value range from the silica gel TLC plate developed in the organic phase of a biphasic or a corresponding monophasic solvent system. Despite their simplicity, there has been an absence of theoretical support and a deficiency of reported experimental evidence. The present study explores the theory required to develop correlations between Rf and K. All theoretical models surmise that the optimal Rf value range should be centered at 0.5. In order to validate the feasibility of the concept of matching Rf and K values, 43 natural products and six solvent system families were investigated. Out of 62 correlations, 45 resulted in matched Rf and K values. Based on this study, practical guidelines for the TLC-based prediction strategy are provided. These approaches will equip CCS users with an updated understanding of how to apply the TLC-based solvent system selection strategy to accelerate a targeted selection of CCS conditions.

Choosing a suitable solvent system for a countercurrent chromatography separation presents a challenge for many researchers. In this study, we introduce a quick method of separating a target compound from the bark of Zanthoxylum myriacanthum var. pubescens by countercurrent chromatography. This method relies on the thin-layer chromatography based generally useful estimation of solvent systems. This paper will present how to quickly choose a suitable solvent system with a thin-layer chromatography based generally useful estimation of solvent systems working chart. O-Methyltembamide (1) was enriched by countercurrent chromatography using n-hexane/ethyl acetate/methanol/water (6:4:6:4) as the solvent system. Further purification was achieved by high-performance liquid chromatography with purities of 98.2% from Z. myriacanthum var. pubescens bark.