Energy Band Alignment and Redox-Active Sites in Metalloporphyrin-Spaced Metal-Catechol Frameworks for Enhanced CO2 Photoreduction

Two new chemically stable metalloporphyrin-bridged metal-catechol frameworks, InTCP-Co and FeTCP-Co, were constructed to achieve artificial photosynthesis without additional sacrificial agents and photosensitizers. The CO₂ photoreduction rate over FeTCP-Co considerably exceeds that obtained over InTCP-Co, and the incorporation of uncoordinated hydroxyl groups, associated with catechol, into the network further promotes the photocatalytic activity. The iron-oxo coordination chain assists energy band alignment and provides a redox-active site, and the uncoordinated hydroxyl group contributes to the visible-light absorptance, charge-carrier transfer, and CO₂-scaffold affinity. With a formic acid selectivity of 97.8 %, FeTCP-OH-Co affords CO₂ photoconversion with a reaction rate 4.3 and 15.7 times higher than those of FeTCP- Co and InTCP-Co, respectively. These findings are also consistent with the spectroscopic study and DFT calculation.     

Quantitative determination of alkylated quaternary amines and their n-hydroxylated metabolites in an enzyme incubation matrix by liquid chromatography electrospray ionization mass spectrometry

A simple, rapid and sensitive reversed-phase liquid chromatography method coupled to electrospray ionization mass spectrometry has been developed for studying the in vitro metabolism of the long-chain quaternary ammonium compounds dodecyltrimethylamine, tetradecyltrimethylamine and hexadecyltrimethylamine. Samples were prepared from the biological matrix by a simple protein precipitation stage. The separation was performed using a BDS Hypersil C8 3 microm particle size (100 x 3 mm i.d.) column with a fast gradient separation (60% B to 100% B) using a mobile phase of 10 mm aqueous ammonium acetate (pH 4.0, with 0.06% triethylamine; (A)-acetonitrile (B) at 0.7 mL min(-1). To minimize contamination of the MS source a switching value was used to divert the solvent front to waste. Decylammonium bromide was used as the internal standard and analytes were identified and quantified by positive ion electrospray selected ion monitoring of their intact molecular cations. The assay had a limit of quantitation of 0.25 microm (6.25 pmol on column) and was linear over the range 0.25--100 microm assay concentration for this series of long-chain quaternary amines. The precision of intra- and inter-day assays was better than 19% and the accuracy was between 93 and 109%. The method was used to assess the in vitro metabolism of the quaternary amines by wild-type cytochrome P450 enzyme CYP 4 A 1 and mutants in an artifical membrane system.     

羟基化多壁碳纳米管分散固相萃取/气相色谱-质谱测定茶叶中有机氯农药和拟除虫菊酯类农药残留

建立了羟基化多壁碳纳米管作为吸附剂的改进Qu ECh ERS方法,联合气相色谱-质谱联用法快速检测茶叶中24种有机氯农药和拟除虫菊酯类农药残留量。茶叶样品中的农药残留经正己烷-丙酮(2∶1)提取,以羟基化多壁碳纳米管(MWCNTs-OH)和N-丙基乙二胺键合固相吸附剂(PSA)吸附提取液中的杂质,提取液离心后过滤,经气相色谱-电子轰击源质谱法测定,外标法定量。研究了不同吸附剂种类、提取溶剂、吸附剂用量对提取净化效率的影响。在优化实验条件下,目标物质在0.01~0.50 mg/kg范围内线性关系良好。空白茶叶样品在低、中、高3个加标水平下的平均回收率为78.6%~109.6%,相对标准偏差(n=5)为2.1%~9.3%;方法的定量下限为0.002~0.050 mg/kg。该方法操作简单、快速、灵敏、成本低,能满足茶叶中常见有机氯和拟除虫菊酯类农药残留的检测要求,特别适合在小型实验室和企业中推广使用。     

多氯联苯的羟基化代谢产物及其内分泌干扰机制

羟基多氯联苯是典型持久性有机污染物(POPs)--多氯联苯在生物体内的主要活性代谢产物,已在许多野生动物和人体内被检出.由于其化学结构与天然雌激素、甲状腺激素十分类似,因此羟基多氯联苯的内分泌干扰效应近年来已开始受到国际上的高度关注.本文对多氯联苯的代谢途径、羟基多氯联苯在生物体内的浓度水平、内分泌干扰及其多种毒性作用机制进行了综述.有关对多氯联苯的活性代谢产物--羟基多氯联苯的深入研究,将有助于进一步揭示多氯联苯的毒性机制,为我国早日建立有效的POPs污染危害评价与早期预警系统提供科学依据.     

自组装单层膜的制备与应用

本文综述了自组装单层膜制备及应用技术的最新发展,分别对有机硅烷/羟基化表面和硫醇/金两种重要的自组装单层膜体系的制备新技术以及在制膜技术和分子电子学等领域的最新应用进行了总结.     

Synthesis of dihydroxylated polyamines from an erythronolactone

The opening of protected erythronolactone by an amine or a diamine furnished hydroxy-amides. Their multistep functional conversion led to either selectively protected or free dihydroxy-polyamines.     

The Functionality of Surface Hydroxy Groups on the Selectivity and Activity of Carbon Dioxide Reduction over Cuprous Oxide in Aqueous Solutions

Carbon dioxide (CO₂) reduction in aqueous solutions is an attractive strategy for carbon capture and utilization. Cuprous oxide (Cu₂O) is a promising catalyst for CO₂ reduction as it can convert CO₂ into valuable hydrocarbons and suppress the side hydrogen evolution reaction (HER). However, the nature of the active sites in Cu₂O remains under debate because of the complex surface structure of Cu₂O under reducing conditions, leading to limited guidance in designing improved Cu₂O catalysts. This paper describes the functionality of surface‐bonded hydroxy groups on partially reduced Cu₂O(111) for the CO₂ reduction reaction (CO₂RR) by combined density functional theory (DFT) calculations and experimental studies. We find that the surface hydroxy groups play a crucial role in the CO₂RR and HER, and a moderate coverage of hydroxy groups is optimal for promotion of the CO₂RR and suppression of the HER simultaneously. Electronic structure analysis indicates that the charge transfer from hydroxy groups to coordination‐unsaturated Cu (Cu_CUS) sites stabilizes surface‐adsorbed COOH*, which is a key intermediate during the CO₂RR. Moreover, the CO₂RR was evaluated over Cu₂O octahedral catalysts with {111} facets and different surface coverages of hydroxy groups, which demonstrates that Cu₂O octahedra with moderate coverage of hydroxy groups can indeed enhance the CO₂RR and suppress the HER.     

羟基查尔酮类衍生物的合成

4-羟基苯乙酮或2,4-二羟基苯乙酮与取代苯甲醛在乙二醇溶液中,以硼酸为催化剂,于110～120℃反应6 h,再经柱分离精制得羟基查尔酮衍生物.产物经红外光谱、核磁共振谱、质谱确认结构.此法合成虽然收率不太高,但利用此法可更简便地一步合成出羟基查尔酮类衍生物.     

A comparison of eight commercial reverse-phase (ODS) columns for the separation of hydroxylated derivatives of 7,12-dimethylbenz(a)anthracene

This paper presents an evaluation of a number of commercially available octadecylsilane columns. The separation of four 7,12-dimethylbenz(a)anthracene (DMBA) derivatives namelycis- andtrans-5,6-dihydroxy DMBA,trans-8,9-dihydro-8,9-dihydroxy DMBA, and 7,12-dihydroxymethyl benz(a)anthracene (BA) was compared under identical conditions comprising of a concave gradient (No. 4) from 20 to 70% acetonitrile/water for 75 minutes at flow rate of 1ml/min. A direct correlation between percent carbon loading and retention behavior was observed for bonded phases prepared from silica particles with similar surface areas. Other column performance parameters, such as capacity factors, separation ratios and resolution between peaks for the solutes examined were also calculated and are discussed.     

三维多孔碳纳米管-还原氧化石墨烯复合气凝胶应用于高性能对称超级电容器

以羟基化的碳纳米管(CNT-OH)和自制的氧化石墨烯(GO)为原料，通过氧化还原自组装的水热合成策略制备了碳纳米管-还原氧化石墨烯(CNTs-rGO)三维气凝胶，并探究了水热温度对三维气凝胶的影响，利用扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)和X射线光电子能谱(XPS)对材料的结构、形貌进行了表征，并对其进行电化学性能测试。其中，在140℃下合成的气凝胶CNTs-rGO展示了最佳的电化学性能，在1 A·g^-1电流密度下的比电容高达294.65 F·g^-1，循环伏安曲线在50 mV·s^-1扫速下的形状仍然近似于矩形，展示了良好的可逆性。将其作为正极和负极材料组装的对称超级电容器在功率密度为249.8 W·kg^-1时的最大能量密度为3.744 Wh·kg^-1，在1 A·g^-1下循环10 000次后，其电容保持率和库仑效率均约为100%。优异的电化学性能主要归因于CNTs-rGO复合材料疏松多孔的三维立体结构，这保证了离子的快速运输，同时CNTs和rGO的交联结构提高了电导率，充分发挥了CNTs和rGO的化学和电学性能。