Water-Promoted,Silver–Phosphine Complex–Catalyzed Stereoselective Cyclization of 2-(1-Hydroxy-3-arylprop-2-ynyl)phenols Leading to a Highly Efficient Approach to Aurones

Silver–phosphine complexes can be utilized as highly efficient catalysts for the cyclization of 2-(1-hydroxy-3-arylprop-2-ynyl)phenols (1) to give product 2, key intermediates to synthesize aurones (4), with good yields and stereoselectivities in water–toluene mixed solvent. With fluoride as the counteranion, complete E- or Z- stereoselectivities were achieved at high temperature or room temperature, respectively. Furthermore, after removing water from the reaction mixtures, the toluene solution containing crude products 2 can be treated by MnO₂ directly without further purification, to give aurones 4 in good yields.      

Density functional study of organocatalytic mannich‐type reactions: Insight into reverse diastereoselectivities arising from catalysts with different scaffolds

Density functional study have been carried out to investigate the stereoselectivities in the Mannich‐type reactions promoted by five typical amino acid catalysts with different scaffolds. The reverse diastereoselectivities in the cyclic and acyclic α‐ and β‐amino acids‐promoted Mannich reactions have been satisfactorily explained by the density functional theory (DFT) methods at the SMD/M06‐2X/6‐31G** computational level. The activation strain analysis has been used to account for the selectivity‐switching for these selected bifunctional catalysts. © 2015 Wiley Periodicals, Inc.     

Ligand-promoted reaction on silver nanoparticles: phosphine-promoted, silver nanoparticle-catalyzed cyclization of 2-(1-hydroxy-3-arylprop-2-ynyl)phenols

A highly efficient annulation of 2-(1-hydroxy-3-arylprop-2-ynyl)phenols leading to the key intermediates to synthesize aurones was catalyzed by silver nanoparticles/carbon black-supported silver nanoparticles. In the presence of phosphine ligand, both the catalysts show excellent catalytic activities in the reaction and give the products with good yields as well as excellent regio- and stereo-selectivities in a water-toluene mixed solvent. Furthermore, the catalysts can be recovered and recycled effectively several times.     

直、交流法对比研究互感现象

为了正确分析互感现象,引入了同名端的概念,分别用直、交法测定同名端。     

Synthesis,Characterization of NR@SiO2/PNIPAm-co-Ppa Composite Nanogel and Study On Its Application in Photodynamic Therapy

In the present study, a novel composite nanogel based on fluorescence resonance energy transfer (FRET) and its application for photodynamic therapy is reported. First of all, nanoparticles of silica doped with Nile Red (NR) were prepared by Stöber method, then they were decorated by γ-methacryloxypropyltrimethoxysilane (MPS) to prepare MPS decorated NR@SiO₂ nanoparticles, and finally they were copolymerized with N-isopropylacrylamide (NIPAm) and Pyropheophorbide-a (Ppa) by free radical copolymerization, and composite nanogel of NR@SiO₂/PNIPAm-co-Ppa was fabricated. The microstructure of the as-prepared nanogel was characterized by Fourier transform infrared spectrum (FTIR), photoluminescence (PL), UV–Visible spectrophotometer (UV–Vis), dynamic light scattering (DLS) and transmission electron microscopy (TEM). PL spectrum indicated that, under irradiation of visible light source, energy can be transferred from NR to Ppa. UV–Vis spectrum demonstrated that aggregation of Ppa is prevented efficiently and Ppa exists as “monomer” state in the composite nanogel. Under irradiation of laser, singlet oxygen (¹O₂) can be produced efficiently by excited nanogel. The in vitro cytotoxicity test showed that HeLa cells can be killed by the composite nanogel.

     

A Novel Labeling Reagent of 2-(12-Benzo[b]acridin-5-(12H)-yl)-acetohydrazide for Determination of Saturated and Unsaturated Fatty Acids in Traditional Chinese Herbs by HPLC-APCI-MS

A new fluorescence labeling reagent 2-(12-benzo[b]acridin-5(12H)-yl)-acetohydrazide (BAAH) has been designed for fatty acids labeling. Eleven fatty acids containing seven saturated and four unsaturated fatty acids were used to evaluate the analytical potential of this reagent. The labeling reaction of BAAH with fatty acids was completed at 85?°C for 60?min using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC·HCl) as the condensing agent. Separation of the derivatized fatty acids was carried out on a reversed-phase Thermo Hypersil Gold C18 column (4.6?mm?×?250?mm, 5?μm) in combination with a gradient elution with a good baseline resolution. The fluorescence excitation and emission wavelengths were set at λ_ex 280 and λ_em 510?nm, respectively. The identification was carried out by the online APCI-MS in positive-ion detection mode. Linear correlation coefficients for all fatty acid derivatives were of >0.9994. Detection limits, at a signal-to-noise ratio of 3:1, were 3.89–12.5?nmol?L^?1 for the labeled fatty acids. The developed method was successfully applied to the accurate determination of fatty acids in five traditional Chinese herbs with satisfactory results.