Synthesis and characterization of MCM-48 tubular membranes

MCM-48 membranes have been prepared on alumina supports of different pore sizes. A battery of characterization techniques has been used to study the physical properties and the quality of the membranes prepared. The highest quality membranes were prepared on supports with pore size of up to 60 nm. The MCM-48 membranes were tested in the separation of gas phase mixtures and a cyclohexane/O₂ selectivity higher than 270 was obtained. The selective separation of organic compounds from inert components is a result of the cooperative effects of capillary condensation in MCM-48 pores and of the specific interactions of the permeating compounds and the membrane material.     

Selective detection of Fe(III) ions in aqueous solution with a 1,8-diacridylnaphthalene-derived fluorosensor

The syn-isomer of 1,8-bis(4,4′-diisopropyl-9,9′-diacridyl)naphthalene, 1, has been prepared by two consecutive Pd(PPh₃)₄-catalyzed Stille cross-coupling steps. This highly congested sensor undergoes Fe(III)-selective fluorescence quenching in water/acetonitrile even in the presence of excess of other metal ions.     

Characterization of cyclodextrin-modified infrared chemical sensors: Part I. Modeling the mechanisms of interaction

To explore the properties of cyclodextrins (CDs) as an optical sensing phase, the behavior of immobilized CD in interaction with analytes was studied in this work. CDs having different cavity sizes were immobilized onto the surface of infrared (IR) internal reflection-sensing element (IRE) to kinetically monitor the behavior of CD in interaction with analytes. Several aromatic compounds having various molecular sizes and functional groups were used to characterize the interaction mechanism. A two-layer modification method was proposed in this work, which utilized a thin hydrophobic film (polyvinyl benzyl chloride) to stick on the IRE and to covalently bond to the CDs through an ethylene diamine linker. The synthesized CD phases exhibited high stability in aqueous solution. To analyze the behavior during the formation of complexes between the guest molecules and the CD phases, we modeled the interaction behavior and treated the kinetic data with the theoretical equations developed in this work. The results indicate that the behavior of the interaction between guest molecules and CDs was explained by considering the formation of two types of complexes: adsorbed complexes and inclusion complexes. The formation of the inclusion complexes was relatively fast, the time required to reach equilibrium could be shorter than a few minutes. The adsorbed complexes were also observed, but their rate of formation was relatively slow; equilibrium could be reached at times greater than 60 min. Based on the signals observed under equilibrium conditions, the concentration of inclusion complexes was approximately three times than that of the adsorbed complexes.     

Zeolite NaY-mediated oxidation of dyes with H2O2: unique heterogeneous non-transition metal center cleavage of H2O2 under visible light irradiation

This study investigated the visible-light catalysis mediated by zeolite NaY on the oxidation of dyes with H₂O₂. The results demonstrated that zeolite NaY acts as a sink for the electron from the photo-excited dye in the heterogeneous catalysis. Furthermore, the electron can effectively activate H₂O₂ to produce ^·OH radical that is a powerful oxidant for the oxidation of dye at room temperature. The effects of the framework topology, Si/Al ratio, and exchangeable cation of the zeolite on the oxidation of various dyes were also shown.     

Voltammetry and electrocatalytic properties of cobalt (1,4,8,12-tetraazacyclopentadecane) in aqueous solution

Summary The spectrochemical, electrochemical and electrocatalytic properties of Co[15]aneN₄ ([15]aneN₄ = 1,4,8,12-tetraazacyclopentadecane) have been investigated. The results show that, in aqueous solution, this compound mainly exists as three species whose axial coordination positions are occupied by water and/or hydroxy ligands; it is marginal whether other substrates such as Cl^– and NO _inf3 ^sup– interact with the central ion in acid-base solutions. The approximate Pourbaix diagram of Co^III/II[15]ane N₄ was determined. There is an electrochemically-induced isomerization between two trans conformational isomers of the Co[15]aneN₄ complexes in acid and netural solutions. The Co[15]aneN₄ complex has electrocatalytic properties for reduction of nitrate and nitrite only in strong alkaline solution.     

二氢茉莉酮酸甲酯的简便合成方法

本文报道二氢茉莉酮酸甲酯的简便合成方法。先由丁二酸和庚酰氯反应得到2-戊基-1,3-环戊二酮(1),再用甲醇醚化1,可得到2-戊基-3-甲氧基-环戊-2-烯酮(2)。2与丙二酸二甲酯反应生成(2-戊基-3-酮-1-环戊烯-)基乙酸甲酮(3)。最后,催化氢化3,便可得到二氢茉莉酮酸甲酯(4)。     

Liquid-phase parallel synthesis of tetrahydro-β-carbolines

Parallel synthesis of β-carbolines on soluble polyethylene glycol (PEG-OH) support is demonstrated. One-pot condensation of polymer-bound tryptophan residues with various aldehydes and ketones has been carried out in the presence of p-TSA as a catalyst to deliver immobilized 1,2,3,4-tetrahydro-β-carbolines. Subsequent disengagement of the appendant from the polymer support afforded the desired products in good yield and acceptable purity.     

Aldol reactions of a cyclobutanone enolate

Addition of an aldehyde and zinc chloride to a cyclobutanone enolate, prepared by the reaction of an α-chlorocyclobutanone with dimethylcopperlithium, gave an aldol adduct in good yield.