Effect of the Secondary Reduction on the Enantioselectivity and Function of Additives in the Chiral Oxazaborolidine‐Catalyzed Asymmetric Borane Reduction of Ketones

The secondary reduction in the direct and oxazaborolidine‐catalyzed asymmetric borane reduction of ketones was investigated by the use of GC/MS tracing titration and control experiments. The results indicate that the secondary reduction affects the enantioselectivity only in noncoordinated solvents at low temperature and not under the usual catalytic reduction conditions because the intermediate alkoxyborane is unstable and quickly converts to borane and dialkoxyborane. The function of an alcohol additive in the asymmetric borane reduction of ketones is to consume excess borane in the reduction system thus inhibiting noncatalytic reduction, which leads to increased enantioselectivity in the catalytic reduction.     

具有三维交叉孔道的新型亚磷酸锌的合成与结构

本文报道了一种新型三维亚磷酸锌[HO(CH₂)₂NH₃]₂•[Zn₃(HPO₃)₄]的合成和晶体结构。在它的结构中，ZnO₄和HPO₃严格按照顶点连接的方式交替相连。骨架结构存在两个沿着不同方向无限延伸的由ZnO₄和HPO₃组成的四元环链，在[0 1 0]、[0 4 15]和[0 -4 15]三个方向形成了三个交叉8元环孔道，有机胺阳离子起着平衡电荷和稳定骨架的结构。它的晶体数据为：[HO(CH₂)₂NH₃]₂•[Zn₃(HPO₃)₄],M=640.21, 正交晶系, Fdd2空间群, a=2.8528, b=0.8426, c=1.6159nm, Z=8, V=3.884nm³, R₁=0.0219, wR₂=0.0544。     

Preparation of spherical spinel LiMn2O4 cathode material for lithium ion batteries

A novel process is proposed for synthesis of spinel LiMn₂O₄ with spherical particles from the inexpensive materials MnSO₄, NH₄HCO₃, and NH₃H₂O. The successful preparation started with carefully controlled crystallization of MnCO₃, leading to particles of spherical shape and high tap density. Thermal decomposition of MnCO₃ was investigated by both DTA and TG analysis and XRD analysis of products. A precursor of product, spherical Mn₂O₃, was then obtained by heating MnCO₃. A mixture of Mn₂O₃ and Li₂CO₃ was then sintered to produce LiMn₂O₄ with retention of spherical particle shape. It was found that if lithium was in stoichiometric excess of 5% in the calcination of spinel LiMn₂O₄, the product had the largest initial specific capacity. In this way spherical particles of spinel LiMn₂O₄ were of excellent fluidity and dispersivity, and had a tap density as high as 1.9 g cm^–3 and an initial discharge capacity reaching 125 mAh g^–1. When surface-doped with cobalt in a 0.01 Co/Mn mole ratio, although the initial discharge capacity decreased to 118 mAh g^–1, the 100th cycle capacity retention reached 92.4% at 25°C. Even at 55°C the initial discharge capacity reached 113 mAh g^–1 and the 50th cycle capacity retention was in excess of 83.8%.     

Application of water as a solvent in microwave-assisted extraction for analysis of PCBs and CBzs in fly ash

Polychlorinated biphenyls (PCBs) and chlorobenzenes (CBzs) are two classes of dioxin precursors formed in municipal solid waste incinerators (MSWIs); they produce negative health effects similar to those of dioxins. Reducing the analytical time required for determining the concentrations of these compounds in MSWIs is important for quickly evaluating their importance and assessing associated health risks. In the present study, water is used as a safe and environmentally friendly solvent in microwave-assisted extraction (MAE) for PCB and CBz analyses. MAE is compared with traditional Soxhlet extraction (SE) to determine the extraction efficiencies. The evaluation of extraction efficiencies shows that MAE has a high extraction efficiency compared with that of SE when water content is lower than 60%. Furthermore, the extraction time and organic solvent consumption are reduced with MAE compared with SE.     

Synthesis and Preliminary Anti‐bacterial Activity of Some 4‐Substituted‐N1‐2‐pyridylsulfanilamide Derivatives

2‐Amino‐4‐ethoxycarbonylpyridine 1 was used as a starting material in the synthesis of some 4‐substituted‐N¹‐2‐pyridylsulfanilamide derivatives to evaluate their antimicrobial activity. The obtained compounds were of no particular effect against the tested organisms except for a noticeable inhibition of B. subtilis, which was of varying extents but remained clearly significant.     

混合金属氧化物柱撑α-磷酸锆的研究

制备、表征了混合铝/铬金属氧化物柱撑α-磷酸锆(Al/Cr-ZrP),并对胶体化使用有机胺的种类、柱化液金属离子浓度以及金属离子用量等因素进行了研究。研究表明以乙醇胺为胶体化有机胺比使用正丙胺为胶体化有机胺所得到的产物的层间距更大;采用较低金属离子浓度、较高金属离子用量有利于Al/Cr-ZrP的合成。在Al/Cr比为1、以正丙胺为胶体化有机胺、金属离子浓度为0.067mol·L^-1、金属离子用量为6.67CEC的条件下,制备出了混合金属氧化物柱撑α-磷酸锆,其层间距可达3.60nm,     

SUPERCRITICAL-PHASE PROCESS FOR SELECTIVE SYNTHESIS OF HEAVIER HYDROCARBONS FROM SYNGAS OVER ARu/Al_2O_3 CATALYST

在Ｒｕ／Ａｌ２Ｏ３催化剂上进行了超临界条件下的固定床费托合成。研究了催化剂孔尺寸、α－Ｃ１４烯共进料和反应温度对费托合成产物分布的影响     

RExOy.nH2O对氟离子的吸附性能

La、Ce等稀土水含氧化物对阴离子的吸附性早有研究「‘－‘1，但从混合轻稀土氯化物制得的水合氧化物吸附F一的研究报道较少．为探讨难溶金属水合氧化物的除氟性能，本文以混合轻稀土氯化物为原料，制得其水含氧化物（RExOy·nH。O），采用高聚物造粒，研究了粒状RExOy·nH。O对F一的吸附性能及吸附机理．所用混合轻稀土氯化物由包头钢铁稀土公司提供，其主要组成（以氧化物计）为：CeO。（50％）、Nd。O3（25％）、La。O。（15％）、P36Oll（8％）．聚丙烯睛分子量为（2．5～5）X10‘．其它试剂为分析纯．RExO．·nH。O参照文…     

An azo dye for photodynamic therapy that is activated selectively by two-photon excitation

Two-photon photodynamic therapy (TP-PDT) is a promising approach for the treatment of cancer because of its better penetration depth and superior spatial selectivity. Here, we describe an azo group containing cyclized-cyanine derivatives (ACC1 and ACC2) as a two-photon activated, type I based photosensitizer (PS). These small-molecule and heavy atom-free organic dyes showed marked reactive oxygen species (ROS)-generating ability under physiological conditions, as well as fast loading ability into the cells and negligible dark toxicity. Live cell analyses with one- and two-photon microscopy revealed that these dyes showed higher ROS generation ability upon two-photon excitation than upon one-photon excitation via the type I process. The PSs have superior PDT properties compared to conventional Visudyne and 5-ALA under mild conditions. These characteristics allowed for precise PDT at the target region in mimic tumor spheroids, demonstrating that the developed TP PS could be useful in efficient PDT applications and in designing various PSs.

Azo containing dyes as a two-photon selective and type I based photosensitizers (PSs) were developed that exhibit excellent photodynamic therapy properties under mild condition.     

Probe metal binding mode of imine covalent organic frameworks: cycloiridation for (photo)catalytic hydrogen evolution from formate

Metalation of covalent organic frameworks (COFs) is a critical strategy to functionalize COFs for advanced applications yet largely relies on the pre-installed specific metal docking sites in the network, such as porphyrin, salen, 2,2′-bipyridine, etc. We show in this study that the imine linkage of simple imine-based COFs, one of the most popular COFs, readily chelate transition metal (Ir in this work) via cyclometalation, which has not been explored before. The iridacycle decorated COF exhibited more than 10-fold efficiency enhancement in (photo)catalytic hydrogen evolution from aqueous formate solution than its molecular counterpart under mild conditions. This work will inspire more functional cyclometallated COFs to be explored beyond catalysis considering the large imine COF library and the rich metallacycle chemistry.

This study describes cyclometallation as a new metal binding mode for imine-based COFs. The iridacycle decorated COF could be used for catalytic hydrogen evolution from aqueous formate solution with high stability and high efficacy.