Dendrimers Functionalized with Palladium Complexes of N-, N,N-, and N,N,N-Ligands

Pyridine, pyridine imine, and bipyridine imine ligands functionalized by a phenol have been synthesized and characterized, in many cases by X-ray diffraction. Several of these N-, N,N-, and N,N,N,-ligands have been grafted onto the surface of phosphorhydrazone dendrimers, from generation 1 to generation 3. The complexation ability of these monomers and dendrimers towards palladium(II) has been assayed. The corresponding complexes have been either isolated or prepared in situ. In both cases, the monomeric and dendritic complexes have been tested as catalysts in Heck couplings and in Sonogashira couplings. In some cases, a positive dendritic effect has been observed, that is, an increase of the catalytic efficiency proportional to the dendrimer generation.     

Magnetic Titanium Dioxide Nanocomposites for Surface‐Enhanced Resonance Raman Spectroscopic Determination and Degradation of Toxic Anilines and Phenols

Mesoporous M‐TiO₂ NCs, functionalized by PATP, can capture toxic anilines and phenols by azo coupling. Loading these nanodevices with Ag NPs offers the possibility for a sensitive quantitative determination of target compounds by SERRS spectroscopy, which allows multiplex detection because of the specific vibrational fingerprints. Sensitivity and selectivity can be further enhanced by concentrating the hybrid particles by an external magnet and compound‐specific binding (anilines versus phenols). The bound toxic compounds can be degraded by TiO₂‐assisted photocatalysis after removal of the loaded hybrid particles from the sample solution with an external magnet. The degradation process can be enhanced in the presence of plasmonic Ag nanostructures.     

β-PbO2/TiO2纳米管电极的制备及其电催化降解苯酚

采用阳极氧化法和脉冲电沉积制备出β-PbO2改性TiO2纳米管(β-PbO2/TiO2-NTs)电极,通过扫描电子显微镜(SEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)等技术手段对制备的β-PbO2/TiO2-NTs电极的表面形貌和结构进行了表征。结果表明,该方法成功地将β-PbO2纳米颗粒分散在TiO2纳米管中,通过电催化降解苯酚评价了β-PbO2/TiO2-NTs电极的电催化活性,实验结果表明,在TiO2-NTs中电沉积β-PbO2提高了电极的电催化活性,对苯酚的降解达到83%。     

Hierarchical Hybrid Peroxidase Catalysts for Remediation of Phenol Wastewater

We report a new family of hierarchical hybrid catalysts comprised of horseradish peroxidase (HRP)–magnetic nanoparticles for advanced oxidation processes and demonstrate their utility in the removal of phenol from water. The immobilized HRP catalyzes the oxidation of phenols in the presence of H₂O₂, producing free radicals. The phenoxy radicals react with each other in a non‐enzymatic process to form polymers, which can be removed by precipitation with salts or condensation. The hybrid peroxidase catalysts exhibit three times higher activity than free HRP and are able to remove three times more phenol from water compared to free HRP under similar conditions. In addition, the hybrid catalysts reduce substrate inhibition and limit inactivation from reaction products, which are common problems with free or conventionally immobilized enzymes. Reusability is improved when the HRP–magnetic nanoparticle hybrids are supported on micron‐scale magnetic particles, and can be retained with a specially designed magnetically driven reactor. The performance of the hybrid catalysts makes them attractive for several industrial and environmental applications and their development might pave the way for practical applications by eliminating most of the limitations that have prevented the use of free or conventionally immobilized enzymes.     

BiOI/Bi_2WO_6对甲基橙和苯酚的光催化降解及光催化机理(英文)

采用简单的沉积方法制备了不同碘化氧铋含量的BiOI/Bi2WO6光催化剂,通过X射线衍射(XRD)、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HR-TEM)、紫外-可见漫反射光谱(UV-Vis DRS)和BET比表面积测量对其进行了表征。在紫外和可见光的照射下,使用甲基橙和苯酚的光催化降解评价了BiOI/Bi2WO6催化剂的光催化性能。结果表明:与商业P25和纯Bi2WO6相比,13.2%BiOI/Bi2WO6光催化剂具有更高的紫外和可见光催化性能。这明显增加的光催化活性主要归功于光生电子和空穴在Bi2WO6和BiOI界面上的有效转移,降低了电子-空穴对的复合。基于BiOI和Bi2WO6的能带结构,提出了光生载流子的一种转移过程。自由基清除剂的实验表明,·OH,h+,·O2-和H2O2,特别是h+,共同支配了甲基橙和苯酚的光催化降解过程。     

ZnCl2、KOH和HNO3改性MWCNT对苯酚的吸附行为研究

通过扫描电子显微镜、X射线衍射仪、N₂吸附分析仪及Boehm滴定法获得ZnCl₂、KOH和HNO₃化学处理对高纯多壁碳纳米管的结构和表面含氧官能团的影响,通过批处理实验考察吸附条件（吸附时间、初始浓度、温度）对处理前后的碳纳米管吸附苯酚行为的影响,并采用准一级、准二级、Evolich动力学模型和热力学方程拟合其吸附数据,分析其动力学行为、热力学行为和吸附机理。结果表明,虽然ZnCl₂、KOH和HNO₃化学处理法均未对碳纳米管BET比表面积产生显著影响,但会影响其表面化学性质（即,对于ZnCl₂和KOH化学处理降低表面羧基、内酯基含量和增大碱性官能团量,而对于HNO₃化学处理可以增大表面羧基、内酯基含量,而碱性官能团略有增加）;改性处理影响碳纳米管去除苯酚效率：由于ZnCl₂和KOH改性处理降低碳纳米管表面羧基量,故其提高了苯酚去除率,而HNO₃处理则略减小碳纳米管的苯酚去除率,可能是由于碳纳米管结构和表面化学性质共同影响所致;碳纳米管的苯酚去除率均随苯酚溶液初始浓度的增大而减小;高温不利于吸附;热力学研究发现碳纳米管吸附苯酚过程是自发的和放热的,属于物理吸附;动力学研究表明,吸附过程符合准二级动力学方程。通过ZnCl₂和KOH化学处理,可以显著提高碳纳米管对苯酚的吸附性能。     

A convenient and efficient H2SO4-promoted regioselective monobromination of phenol derivatives using N-bromosuccinimide

Abstract

A convenient, rapid H₂SO₄-promoted regioselective monobromination reaction with N-bromosuccinimide was developed. The desired para-monobrominated or ortho-monobrominated products of phenol derivatives were obtained in good to excellent yields with high selectivity. Regioselective chlorination and iodination were also achieved in the presence of H₂SO₄ using N-chlorosuccinimide and N-iodosuccinimide, respectively.     

IRMPD Spectra of Protonated Hydroxybenzaldehydes: Evidence of Torsional Barriers in Carboxonium Ions

Protonation at the formyl oxygen atom of benzaldehydes leading to the formation of carboxonium ions yields two distinct isomers, depending on the relative orientation of the proton either cis or trans with respect to the hydrogen atom on the adjacent carbon. In this context, the IR multiple photon dissociation (IRMPD) spectra of protonated ortho, meta, and para-hydroxybenzaldehydes ( OH−BZH⁺ ), delivered into the gas phase by electrospray ionization of hydro-alcoholic solutions, are reported in the 3200–3700 cm⁻¹ spectral range. This range is characteristic of O−H stretching modes and thus able to differentiate cis and trans carboxonium isomers. Comparison between IRMPD spectra and DFT calculations at the B3LYP/6-311++G(2df2p) level suggests that for both p- OH−BZH⁺ and m- OH−BZH⁺ only cis conformers are present in the ion population analyzed. For o- OH−BZH⁺ , IRMPD spectroscopy points to a mixture comprising one trans and more than one cis conformers. The energy barrier for cis–trans isomerization calculated for each OH−BZH⁺ isomer is a measure of the degree of π-electron delocalization. Furthermore, IRMPD spectra of p- OH−BZH⁺ , m- OH−BZH⁺ and protonated phenol (this last used as reference) were recorded also in the fingerprint range. Both the observed C−O and O−H stretching vibrations appear to be a measure of π-electron delocalization in the ions.     

Strongly Basic Anion Exchange Resin Based on a Cross-Linked Polyacrylate for Simultaneous C.I. Acid Green 16, Zn(II), Cu(II), Ni(II) and Phenol Removal

The adsorption ability of Lewatit S5528 (S5528) resin for C.I. Acid Green 16 (AG16), heavy metals (Zn(II), Cu(II) and Ni(II)) and phenol removal from single-component aqueous solutions is presented in this study to assess its suitability for wastewater treatment. Kinetic and equilibrium studies were carried out in order to determine adsorption capacities, taking into account phase contact time, adsorbates’ initial concentration, and auxiliary presence (NaCl, Na₂SO₄, anionic (SDS) and non-ionic (Triton X100) surfactants). The pseudo-second-order kinetic model described experimental data better than pseudo-first-order or intraparticle diffusion models. The adsorption of AG16 (538 mg/g), phenol (14.5 mg/g) and Cu(II) (5.8 mg/g) followed the Langmuir isotherm equation, while the uptake of Zn(II) (0.179 mg^1−1/nL^1/n/g) and Ni(II) (0.048 mg^1−1/nL^1/n/g) was better described by the Freundlich model. The auxiliary’s presence significantly reduced AG16 removal efficiency, whereas in the case of heavy metals the changes were negligible. The column studies proved the good adsorption ability of Lewatit S5528 towards AG16 and Zn(II). The desorption was the most effective for AG16 (>90% of dye was eluted using 1 mol/L HCl + 50% v/v MeOH and 1 mol/L NaCl + 50% v/v MeOH solutions).     

Discovery of Novel Non-Oxime Reactivators Showing In Vivo Antidotal Efficiency for Sarin Poisoned Mice

A family of novel efficient non-oxime compounds exhibited promising reactivation efficacy for VX and sarin inhibited human acetylcholinesterase was discovered. It was found that aromatic groups coupled to Mannich phenols and the introduction of imidazole to the ortho position of phenols would dramatically enhance reactivation efficiency. Moreover, the in vivo experiment was conducted, and the results demonstrated that Mannich phenol L10R1 (30 mg/kg, ip) could afford 100% 48 h survival for mice of 2*LD₅₀ sarin exposure, which is promising for the development of non-oxime reactivators with central efficiency.