Biomimetic Epxidation of Alkenes by Phenyliodonium Diacetate [PhI(OAc)_2] in the Presence of Mn(Ⅲ) Complex of meso-Tetrakis(4-methoxyphenylporphyrin) Acetate Mn[(T4-OCH_3P)P]OAc

We have reported that phenyliodonium diacetate[PhI(OAc)2] can serve as an eco-friendly mild oxidant for the epoxidation of alkenes in the presence of Mn(III) complex of meso-tetrakis(4-methoxyphenylporphyrin) acetate Mn[(T4-OCH3P)P]OAc and imidazole in CH2Cl2.The amounts of the products(%) and selectivities are very dependent upon the electronic and steric properties of the starting alkenes.To evaluate the validity of this catalytic system for C H activation,cyclohexane and ethylbenzene were oxidized under ...     

Dodecatungstophosphoric Acid (H3PW12O40): A Novel and Efficient Recyclable Catalyst for Synthesis of 1,1‐Diacetates from Aromatic Aldehydes in Solvent‐Free System and Their Deprotection

A facile and efficient method for the formation of 1,1‐diacetates from a variety of aldehydes in the presence of a catalytic amount of H₃PW₁₂O₄₀ and acetic anhydride was achieved in good yields at room temperature. The deprotection of the resulting acylals is achieved using the same catalyst in acetone.     

Synthesis and Fluorescent Performance of Fluorescein-functionalized Waterborne Polyurethane

A novel yellow fluorescent diisocyanate 3,6-di(hexamethylene urethano)spiro[xanthene-9,3′-phthalide] diisocyanate (DIX) was synthesized by the reaction of fluorescein with hexamethylene diisocyanate first. Using DIX to substitute partially isophorone diisocyanate (IPDI), a kind of yellow fluorescent waterborne polyurethane DIX-WPU was prepared by blocking the fluorophore of DIX into the polyurethane chain using IPDI, polytetramethylene ether glycol and 2,2-dimethylol propionic acid. The molecular structure of DIX and DIX-WPU was confirmed by means of Fourier transform infrared spectroscopy. The fluorophore is fixed permanently in the polyurethane chain and is difficult to migrate due to the covalent bonding with other component during the synthesis. The fluorescence intensity of DIX-WPU fluorescent dispersion was enhanced greatly comparing with that of fluorescein in a wide range of fluorophore content between 1 × 10^–7 and 1 × 10^–3 mol/L. The fluorescence of DIX-WPU dispersion is very stable not only for the long term storage but also for the fluorescence quencher. It was found that the fluorescence intensity of DIX-WPU increased with the increase of temperature.     

Simple Synthesis of Geminal Diacetates (Acylals) of Aromatic Aldehydes

The geminal diacetates of aromatic aldehydes were prepared from corresponding aldehydes by refluxing with acetic anhydride without any catalysts or even any additional solvent.     

Iodobenzene Diacetate Mediated Oxidation of N-Substituted Hydrazones of Chalcones: An Efficient Regioselective Synthesis of 1,3,5-Trisubstituted Pyrazoles

Iodobenzene diacetate, a relatively benign nonmetallic oxidant, has been utilized efficiently for the oxidation of N-substituted hydrazones of chalcones to afford 1,3,5-trisubstituted pyrazoles under mild reaction conditions.     

二醋酸纤维素接枝丙交酯共聚物的合成与表征

以二醋酸纤维素为接枝骨架,在辛酸亚锡的催化下,通过L-丙交酯的开环接枝聚合反应,合成了二醋酸纤维素和聚丙交酯接枝共聚物(CDA-g-PLA),并采用GPC、FTIR、1H-NMR和DSC对接枝共聚物进行表征.研究了原料质量比、催化剂用量、反应时间、反应温度对单体转化率(C%)、接枝率(G%)的影响.结果表明:反应温度150℃,单体丙交酯与二醋酸纤维素质量比为4:1,反应时间30min,催化剂辛酸亚锡与二醋酸纤维素的质量比为1%时,产物的接枝率较高.     

Efficient method for fabrication of fluorescein derivative/PDAC composite nanofibers and characteristics of their photoluminescent properties

Electrospinning is a simple and cost-effective approach for the production of nanofibers and assemblies with controllable structures. In this work, the pure poly (diallyldimethylammonium chloride) (PDAC) nanofibers with smooth surface and uniform morphology were successfully fabricated by electrospinning. On this basis, fluorescein/PDAC, dibromofluorescein/PDAC, diidofluorescein/PDAC and fluorescein sodium/PDAC composite nanofibers were also fabricated using the same method. The average diameters of the pure PDAC nanofibers increased with the applied field strength and the amount of PDAC in the solutions; and the average diameters ranged from 280 to 450 nm. The morphology of pure PDAC nanofibers has been observed by scanning electron microscopy (SEM) and the photoluminescent properties of fluorescein derivative/PDAC composite nanofibers have been characterized by fluorescence microscopy.     

pH-Responsive amorphous room-temperature phosphorescence polymer featuring delayed fluorescence based on fluorescein

Numerous researchers have paid attention to achieve metal-free phosphorescence by exploring new structures or new mechanisms. Herein, a facile way is introduced to endow a common fluorescence dye, tetrabromofluorescein (4Br-Flu), some fabulous optical characteristics such as dual emission including thermally activated delayed fluorescence, room-temperature phosphorescence (RTP), and the excellent pH-sensitivity. Shortly, 4Br-Flu with good light-emitting properties is composed into the polymer system. The multiple bromine atoms promote the spin-orbit coupling effect and facilitate triplet excitation. Especially, the hydrogen bonding network of the polymer restricts the molecular motion of 4Br-Flu so that the system can emit long-wavelength RTP when 4Br-Flu is doped into polyvinyl alcohol or co-polymerized with acrylamide. Due to the reversible transformation of protonation and deprotonation, the 4Br-Flu based polymer responded to acid and alkali like a phosphorescent switch which makes it an excellent hydrogen chloride/ammonia gas leak detector in dry environment.     

Synthesis,Kinetics, and Equilibrium Study of Highly Sensitive Colorimetric Chemosensor for Monitoring of Copper Ions based on Benzo[f]fluorescein Dye Derivatives

The colorimetric chemosensor 2‐((3,5‐dichloro‐2‐hydroxybenzylidene)amino)‐3′,6′‐dihydroxy‐6‐methyl‐4‐(p‐tolyl)spiro[benzo[f]isoindole‐1,9′‐xanthen]‐3(2H)‐one ( BFFSH ) derived from benzo[f]fluorescein dye was synthesized. NMR and IR spectroscopy as well as mass spectrometry were used to confirm the compound. BFFSH shows potential application for detecting metal ions in aqueous solution. It displays a colorimetric selectivity and sensitivity towards the aqueous solution of Cu²⁺ ions with a detection limit in the nano‐molar range (1.69 nM). In addition, the application of BFFSH was extended for the detection of Cu²⁺ ions in real water samples (tap and synthetic water) with a high recovery percentage. Additionally, the association constant (K_a) of BFFSH , which binds with Cu²⁺ ions based on 2:1 stoichiometry was calculated.     

直接竞争荧光免疫法测定中药材中的黄曲霉毒素B1

本文采用Mannich反应合成黄曲霉毒素B1(AFB1)人工抗原,免疫小鼠制备AFB1单克隆抗体。采用直接搅拌法将异硫氰酸荧光素(FITC)标记AFB1抗体,经Sephadex-50凝胶柱纯化,制得FITC-AFB1荧光标记抗体,分析其免疫学特性,从而建立了一种快速灵敏的直接竞争荧光免疫分析方法(FIA)以用于检测中药材中的AFB1含量。结果表明,AFB1-FITC标记抗体的结合比率为4.19。通过对检测体系多项影响因素的筛选优化,FIA检测方法的标准曲线方程为I=33.45 log C+25.55,R=0.9913,线性检测范围1~100 ng/m L,检测限0.69ng/m L,回收率90.4%~106.6%。该方法具有操作简单、快速灵敏、特异性高等特点,可用于中药材中AFB1的分析测定。