聚乙二醇对TiO2薄膜光致亲水性的促进作用

为了提高TiO₂薄膜的光致亲水性及其持久性, 将聚乙二醇(PEG)2000 引入TiO₂溶胶中, 利用提拉法在载玻片上制备出含PEG的TiO₂薄膜样品, 通过测试样品紫外光照下水滴接触角的变化, 考察不同浓度PEG对TiO₂薄膜光致亲水性能的影响; 并通过测试光照后的亲水薄膜样片暗处放置不同时间后接触角的变化, 比较含PEG的TiO₂薄膜和纯TiO₂薄膜样品的亲水持久性. 结果表明: PEG作为一种非离子型长链分子, 其适量的添加可促进TiO₂薄膜的光致亲水性及其持久性. 基于薄膜样品的傅里叶变换红外(FTIR)光谱和紫外-可见漫反射光谱(UV-Vis DRS)结果, 认为PEG作为空穴捕获剂有助于TiO₂薄膜中Ti³⁺的生成和稳定存在, 进而有助于亲水中心(表面羟基)的形成. 此研究对于TiO₂光自洁涂料的应用很有意义, 也为研究TiO₂的光激发瞬态行为提供了一个可能的简易方法.     

三氧化铬二吡啶、三氧化铬吡啶盐酸盐——两种有效的专用氧化剂

近年来,文献[1]陆续报道了多种能选择地将伯、仲醇氧化为醛和酮的专一氧化剂,例如四醋酸铅吡啶,铬酸叔丁酯,Ｎ氯代丁二烯亚胺,二甲硫醚,硝酸氨铈,三氧化铬的吡啶溶液,其中有些氧化剂制备较复杂,或是制备成本较高,使之应用范围较窄。而三氧化铬的吡啶溶液由于氧化醇时条件温和,产物分离方便,在近年来得到了广泛的应用,例在合成前列腺素和甾体的醛的中间体时,得到了几乎定量的产物。我们对三氧化铬吡啶溶液中最具代表性的氧化剂三氧化铬二吡啶及三氧化铬吡啶盐酸盐的合成、应用及氧化机理作了一些探讨。1　实验部分11　试剂和仪器文中所用试剂…     

A Facile Synthesis of β-Cyclodextrin Monoaldehyde

Cyclodextrinsandtheirderivativeshaveplayedimportantrolesinsuchdiversefieldsaschiralseperation,artificalenZymes,asymmetricsynthesisanddrugdelivery'.ThecyclodextrinmonoaldehydeisanewlydevelopedintermediatetosynthesizenovelderivativesthroughreductiveaminationinthepresenseofsodiumcyanoborohydrideThereportedsynthesisofcyclodextrinmonoaldehydeinvolvedtheoxidationofp-CDmonotosylatebyDMSOinthepresenceofcollidineordiisopropylethylamine",ordirectoxidationofP-CDwithDess-Martinperiodinane(DMP)'.Thel…     

Highly efficient and selective oxidation of secondary alcohols to ketones under organic solvent and transition metal free conditions

The aqueous HBr/H₂O₂ was found to be highly efficient and green catalytic system for the selective oxidation of the secondary alcohols to ketones in excellent yields under organic solvent free conditions. The results of the oxidation of the secondary alcohols with solid alternatives of the aqueous hydrogen peroxide like SPC or SPB are also described.     

Glaser反应研究新进展

Glaser偶联反应是合成二炔化合物的重要反应,广泛应用于有机合成、材料化学等领域.介绍了近年来Glaser偶联反应中溶剂、氧化剂、底物等领域的研究新进展,指出Glaser偶联反应在不断加深其各方面绿色化研究的同时,多功能团底物的Glaser偶联反应与不对称的Glaser偶联反应也值得关注.     

Photocatalytic Reduction of Nitro Compounds Using TiO2 Photocatalyst by UV and Vis Dye-sensitized Systems

Nitro‐aromatic compounds can be photocatalytically reduced into the corresponding amine‐aromatic compounds using TiO₂ as a photocatalyst in the UV/TiO₂/holes scavenger and Vis/TiO₂/dye‐sensitized systems. In the UV/TiO₂/holes scavenger system, reaction substrate alcohols such as methanol could be used as the holes scavengers, and in the Vis/TiO₂/dye‐sensitized system, substrate alcohols could be oxidized to the corresponding aldehydes with high selectivity. When methanol was used as the holes scavengers and the illumination time was 6 h, 87.2% of p‐nitrotoluene could be photocatalytically reduced into p‐toluidine. In the Vis/TiO₂/dye‐sensitized system, the effect of aromatic alcohols for the photocatalytic reduction of nitrobenzene was better than that of other alcohols. At the same time, aromatic alcohols can be easily oxidized, and the production efficiencies of the corresponding aldehydes were higher than those of other alcohols. The possible reaction mechanisms were also proposed.     

High‐Performance UV Protective Waterborne Polymer Coatings Based on Hybrid Graphene/Carbon Nanotube Radicals Scavenging Filler

Ultraviolet (UV) degradation is one of the most important challenges of waterborne coatings in exterior applications. One of the ways to address this issue is addition of radical scavenging species within the polymer matrix. Herein, hybrids of graphene (G) and multiwall carbon nanotubes (CNTs) in different ratios are used as radical scavenging species. Evaluated by electron paramagnetic resonance spectroscopy, it is found that the hybrid made of G/CNTs in ratio of 10:1 efficiently captures and quenches the free radicals. The waterborne polymer composites containing 1 wt% of hybrid G/CNT are synthesized by in situ miniemulsion free radical polymerization using a water soluble initiator. However, due to excellent efficiency to capture free radicals, the polymerization performed using water soluble initiators in the presence of 10:1 G/CNT filler is hindered. This is resolved by physical separation of the free radicals and the scavenging materials within different phases by use of oil soluble initiator. The resulting polymer composites, beside having excellent mechanical resistance, present exceptional stability under accelerated aging conditions during 400 h, suppressing almost completely the UV photodegradation. This is attributed to the efficient radical scavenging of the G/CNTs hybrid filler distributed within polymer matrix, resulting in high‐performance UV protective waterborne composite coatings.     

Titanium (IV) complexes of some tetra‐dentate symmetrical bis‐Schiff bases of 1,6‐hexanediamine: Synthesis,characterization, and in silico prediction of potential inhibitor against coronavirus (SARS‐CoV‐2)

Symmetrical bis‐Schiff bases (LH ₂) have been synthesized by the condensation of 1,6‐hexanediamine (hn) and carbonyl or dicarbonyl. One of the synthesized Schiff bases has been subjected to the molecular docking for the prediction of their potentiality against coronavirus (SARS‐CoV‐2). Molecular docking revealed that tested Schiff base possessed high binding affinity with the receptor protein of SARS CoV‐2 compared with hydroxychloroquine (HCQ). The ADMET analysis showed that ligand is non‐carcinogenic and less toxic than standard HCQ. Schiff bases acting as dibasic tetra‐dentate ligands formed titanium (IV) complexes of the type [TiL(H₂O)₂Cl₂] or [TiL(H₂O)₂]Cl₂ being coordinated through ONNO donor atoms. Ligands and complexes were characterized by the elemental analysis and physicochemical and spectroscopic data including FTIR, ¹H NMR, mass spectra, UV‐Visible spectra, molar conductance, and magnetic measurement. Optimized structures obtained from quantum chemical calculations supported the formation of complexes. Antibacterial, antifungal, and anti‐oxidant activity assessments have been studied for synthesized ligands and complexes.     

环己醇氧化实验的改进

分别使用绿色氧化剂NaClO、H2O2和高铁酸盐对环己醇进行氧化实验,研究了反应时间、氧化剂用量以及催化剂对环己醇转化率的影响,结果表明NaClO是一种反应时间短、对环境友好、易于学生操作的绿色氧化剂。     

The Effects of Ultrasound on the Electro-Oxidation of Sulfate Solutions at Low pH

The electro-oxidation of sulfate solutions is a well-established route for the generation of powerful oxidants such as persulfate. Despite this, the effects of simultaneous ultrasound irradiation during this process has attracted little attention. Herein, we investigate the effects of a low-intensity ultrasonic field on the generation of solution-phase oxidants during the electro-oxidation of sulfate solutions. Our results show that at high current densities and high sulfate concentrations, ultrasound has little effect on the Faradaic and absolute yields of solution-phase oxidants. However, at lower current densities and sulfate concentrations, the amount of these oxidants in solution appears to decrease under ultrasonic irradiation. A mechanism explaining these results is proposed (and validated), whereby anodically-generated sulfate and hydroxyl radicals are more effectively transported into bulk solution (where they are quenched) during sonication, whereas in the absence of an ultrasonic field these radicals combine with one another to form more persistent species (such as persulfate) that can be detected by iodometry.