Latest ArticlesA divergent intramolecular reaction of phosphine tethered alkyne in protic solvent was developed. This provided a novel and simple access to a large variety of (Z)-alkenylphosphine oxides and phospholane oxides. Our preliminary studies suggested that these divergent reactions are closely related to the reaction condition and molecular structure. A possible mechanism of C-P bond cleavage of a pentacoordinated hydroxyphosphorane intermediate was proposed.
In this study, various nonionic surfactants (NS) with different ethylene oxide (EO) numbers and tail lengths and its binary blends with anionic surfactants (AS) were used as emulsifiers for naphthenic oil to form the microemulsion metalworking fluids (MWFs), and the effects of them on the stability of the emulsion system were investigated by formulation triangle method. The results indicated that binary complex surfactants of NS and AS as emulsifiers exhibited better emulsifying effect than that of single NS. NS with different EO numbers and tail lengths presented various emulsifying effects. NS (EO = 10) exhibited the greatest number of stable formulations, especially the TX-10, but no linear relationship existed between the number of stable formulations and the tail length of NS. In addition, aromatic primary alcohol ethoxylate (APAE) series surfactants containing benzene groups similar to the cycloalkanes in the naphthenic oil so that presented the best emulsifying affect and the greatest number of stable formulations. The co-surfactant of sodium dodecyl benzene sulfonate (SDBS) binary blends with NS exerted the best synergistic effect, and the stable formulations numbers were ranged from 5 to 7, next sodium stearate (SS) comes last followed by sodium dodecyl sulfate (SDS-1) and sodium dodecyl sulfonate (SDS-2).
The acetyl ester plays an important role for protection of the hydroxyl groups in carbohydrates synthesis. In the present study, we described an efficient deprotection of acetyl group of pentacyclic triterpenoid by using methanolic ammonia in THF solution. Good selectivity for cleaving gal-C2-OAc group of 3β-hydroxy-olean-12-en-28-oic acid 28-N-2, 3, 4, 6-tetra-O-acetyl-β-D-galactopyranoside (3) was achieved in the presence of methanolic ammonia within 4 h at low temperature (-60℃) in a yield of 56%. The reaction disclosed here provides a new method for the synthesis of C2 selective modified carbohydrates, which is more useful than conventional synthesis procedure that usually requires many steps including temporary regioselective protection and deprotection. When the reaction temperature was increased from -60℃ to room temperature, the cleavage of the other three acetyl groups of galactose in an order of C4-OAc > C3-OAc > C6-OAc was observed. Based on this study, a plausible route for the deacetylation reaction has been proposed.
A new method for the synthesis of 3-thioazaspiro[4,5]trienones was developed using Pd nanoparticle catalysts, which are highly efficient, environmentally friendly and recyclable. Alkynes and thiophene phenols are effectively cyclized by Pd/ZrO2 catalyst under visible light irradiation. The present protocol simply utilizes visible light as the safe and ecofriendly energy source, and the Pd/ZrO2 nanocomposite as photocatalyst provides a simple and practical approach to various 3-thioazaspiro[4,5]trienones in moderate conditions to high yields
Aggregation-induced emission (AIE) active photochromic molecules have attracted growing attention for their versatile applications. Here we designed and synthesized five newly unsymmetrical photochromic diarylethene (DAE) dyads (BTE1-5) by connecting tetraphenylethene (TPE) and aromatic substituent via bithienylethene (BTE) bridge. The chemical structures of those compounds were identified by 1H NMR, 13C NMR and HRMS.The absorption and emission of these dyads were investigated by UV-vis and fluorescence spectroscopy, respectively. The results showed that all those compounds exhibited typically AIE or aggregation-induced emission enhancement (AIEE) characteristic. Particularly, when an aggregation caused quenching (ACQ) fluorophore (triphenylamine) was grafted to the molecule, connecting with TPE via BTE-bridge, the ACQ phenomenon was dissipated and converted to an AIE luminophore, and those compounds exhibited photochromism upon irradiation with alternative UV and visible light. The solution or solid of those compounds showed distinctly fluorescence switching "ON" or "OFF" observation upon irradiation with alternative UV and visible light.It is interesting that BTE1 could be applied in recording and rewritable information storage, and the cyclization quantum yields could be affected by substituent significantly.
Over the past two decades, layer-by-layer (LbL) assembly of micro/nanocapsules has been of interest for the investigation of bio-nano interactions to explore bio-applications, such as drug delivery. The choice of an appropriate template that can be easily dissolved under mild conditions is one of the challenges for the assembly of LbL capsules. Herein, we report the engineering of LbL capsules with tunable morphologies using cuprous oxide (Cu2O) particles as templates. Cu2O particles with cubic, tetradecahedral or spherical morphologies were synthesized via hydrothermal processes, which can be dissolved under mild condition (e.g., sodium thiosulfate solution). The influence of capsule morphologies on cell association was investigated, which indicates that LbL capsules with cubic geometry promoted cell association up to 4 and 9-fold than tetradecahedral and spherical capsules, respectively. The reported method provides a new avenue for the assembly of LbL capsules with different morphologies, which has the potential for better understanding of biological interactions of LbL capsules.
Carbon dots (CDs) with multi-color emissive properties and a high photoluminescent quantum yield (PLQY) have attracted great attention recently due to their potential applications in chemical, environmental, biological and photo-electronic fields. Solvent-dependent effect in photoluminescence provides a facial and effective approach to tune the emission of CDs. In this study, green emissive nitrogen-doped carbon dots (N-CDs) are synthesized from p-hydroquinone and ethylenediamine through a simple hydrothermal method. The as-prepared N-CDs possess a robust excitation-independent green luminescence and a high PLQYof up to 15.9%. Further spectroscopic characterization indicates that the high PLQY is achieved by the balance of nitrogen doping states and the surface passivation extent in CDs. The N-CDs also exhibit solvent-dependent multi-color emissive property and distinct PLQY in different solvents (the maximum can reach up to 25.3%). Furthermore, the as-prepared N-CDs are applied as fluorescence probes to detect acetone and H2O2 in water. This method has exhibited a low detection limit of acetone (less than 0.1%) and a quick and linear response to the H2O2 with the concentration from 0 to 120 μmol/L. This work broadens the knowledge of applying CDs as probes in the bio and chemical sensing fields.
The toxic organic dye contaminants in wastewater are extremely harmful to the ecosystem. Surface enhanced Raman scattering (SERS) is a technique with high sensitivity and chemical specificity which fulfills the requirements for monitoring dye contaminants in wastewater. However, as one of the common dye contaminants, methyl orange (MO) has very weak affinity to metallic surfaces and is difficult to be detected by SERS at low concentrations. Therefore, a new type of SERS substrate with Ag nanoparticle monolayer functionalized by mono-6-deoxy-6-thio-β-cyclodextrin (β-CD-SH) was prepared to efficiently capture and detect MO in wastewater with a limit of detection of 5×10-7 mol/L. The hydrophobic cavity of β-CD is responsible for the efficient trap and enrichment of MO on the Ag NPs surface, achieving a strong SERS signal of MO at low concentrations and at different pH values. This study provides new insight into designing a well-performed adsorbent for the capture and detection of organic contaminants.
Callicarpa bodinieri is a Chinese traditional medicine herbwith anti-inflammatory activity in clinic. Herein, we report two new 9, 10-seco and etherified abietane diterpenoids bodinieric acids J and K(1 and 2)and one known compound (3) isolated from the leaves and twigs of this plant. Their chemical structures were elucidated by detailed spectrometry data analysis and DP4+ NMR calculation methods. Hypothetical biosynthetic pathways of 1-3 were preliminarily speculated. Compound 3 inhibited inflammasome activation and exhibited blockage of NLRP3 inflammasome activation at non-cytotoxic concentrations in vitro.
The concentration of free zinc within insulin-storing vesicles is important for vesicle maturity and therefore requires accurate measurement. However, common small-molecule intensity-based probes and most available genetically encoded Förster resonance energy transfer (FRET)-based sensors for zinc are unsuitable for estimating the free zinc concentration in insulin-storing vesicles. Therefore, we have developed a novel FRET-based zinc sensor based on the RING motif of TRIM72, referred to as ZnT72R, which has an approximate Kd that varies from 6.07±0.28 μmol/L to 7.84±0.42 μmol/L in vitro and a cytosol-calibrated Kd of approximately 55.56±4.59 μmol/L in HEK293 T cells. To pinpoint the free zinc concentration of insulin-storing vesicles, we initially targeted ZnT72R to beta-cell vesicles by fusing them to NPY (neuropeptide Y). Following NPY-ZnT72R labeling, the FRET intensity ratios of vesicles were quantified. We found that the free zinc concentration in insulin-storing vesicles of diabetic db/db mice (28.30±1.33 μmol/L) was significantly lower than that of control mice (41.46±3.53 μmol/L).
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