Recent applications of radical cascade reaction in the synthesis of functionalized 1-indenones

1-Indenones are important scaffolds in natural products, biologically active molecules as well as functional materials. Recently, radical cascade cyclization has emerged as an efficient and powerful strategy for the construction of valuable and versatile functionalized 1-indenones. In this review, the recent advances of this rapidly growing area were summarized. The selected examples have been classified according to the type of reaction substrates such as 1,3-diarylpropynones, 2-alkynylbenzonitriles, arylpropynols, 1,5-enynes and 2-alkynylated bromocinnamates.     

某些分析化学实验教材中均相沉淀概念的误区

目前,均相沉淀法在大学分析化学实验中已很少采用。高锰酸钾间接滴定法测定钙含量是大学分析化学实验中的经典实验之一,历史上存在均相沉淀法和传统沉淀法2种不同的沉淀操作。虽然我国现有大学分析化学实验中已不采用均相沉淀法进行该实验,但在某些分析化学实验教材中,却存在概念混乱的现象,即把传统沉淀法称作均相沉淀法。对这种现象进行了探讨和总结。     

基于结构性思维的生物化学实验教学探索

为了多维度地培养学生的实践创新能力、终身学习能力及信息获取能力等核心素养,以具体实验为例,探讨结构性思维在生物化学实验教学中的综合应用。教学实践表明：结构性思维可使知识更有序、梯度更明确、更易表达,实验操作变得程序化,学生学习倾向主动,是一种多维度地培养学生核心素养的教学模式。     

以羧酸作为酰化剂的酰化反应及其在有机合成中的应用

传统的傅-克酰基化反应以酰氯或酸酐作为酰化剂、路易斯酸作为催化剂。大量路易斯酸催化剂及反应产生的氯化氢都需要后处理,并且酰氯对湿度敏感,储存及使用过程中易发生危险。而以三氟乙酸酐作为活化剂、直接以羧酸作为酰化剂的酰化反应不需要事先将羧酸制成酰氯、酸酐或酰胺,且活化剂三氟乙酸酐及副产物三氟乙酸都能很容易地通过蒸馏回收,因此,这类酰化反应能有效解决传统的傅-克酰基化反应所存在的问题。本文综述了近20年来以三氟乙酸酐作为活化剂、直接以羧酸作为酰化剂的酰化反应方法的发展,以及其在功能有机分子、药物分子和天然产物合成中的应用。     

Ugi/Diels-Alder串联反应在构建杂环化合物中的应用

杂环化合物广泛存在于天然产物和药物分子中,许多杂环化合物还具有潜在生物活性和药理作用。因此,如何快速高效地构建小分子杂环化合物库成为当今有机合成和药物化学领域的研究热点。Ugi反应在多样性导向合成方面具有得天独厚的优势,能够解决待合成化合物数量庞大、结构复杂的难题;同时,Diels-Alder [4+2]环加成反应能够高效构建碳-碳键,以较高的立体选择性和区域选择性合成六元环系。目前,集二者于一身的Ugi/Diels-Alder串联反应在构建杂环化合物方面展现出了巨大优势和无穷潜能。本文以不同类型的DA反应分类:按照呋喃作为双烯体、吡咯作为双烯体、噻吩为双烯体、口恶唑作为双烯体、 1,2,4-三嗪作为双烯体、苯作为双烯体、不饱和键和芳环共同作为双烯体等对UDA串联反应的研究进行了综述。     

Impact of neutral and acidic species on cycloalkenes nucleation

Non-covalent hydrogen bond interactions between the π cloud of cycloalkenes and three atmospheric common nucleation precursors (H₂S, H₂O, and MeOH) have been investigated using DFT and CCSD(T). The structures and the energies of the 1:1 and 1:2 adducts were computed with the B3LYP-D3 method. The analysis of the investigated electronic properties and geometric parameters shows that cyclohexene is a stronger hydrogen bond acceptor than cyclopentene, then followed by 1,4-cyclohexadiene and 1,3-cyclohexadiene. Comparable red shifts of the OH-/SH-stretching vibrational frequencies were noticed for the studied clusters. Increasing the ring size enhances the hydrogen bond interaction, and increasing the π delocalization decreases the hydrogen bond interactions. This is further confirmed by Bader’s quantum theory of atoms in molecules. The nonadditivity effects were observed in the trimolecular complexes. All the complexes were analyzed by energy decomposition analysis to divide the interaction energy into individual components. Furthermore, the dipole moments and atmospheric implications were also investigated.

     

A New Small-Molecule Donor Containing Non-Fused Ring π-Bridge Enables Efficient Organic Solar Cells with High Open Circuit Voltage and Low Acceptor Content

To achieve high open-circuit voltage (V_oc) and low acceptor content, the molecular design of a small-molecule donor with low energy loss (E_loss) is very important for solution-processable organic solar cells (OSCs). Herein, we designed and synthesized a new coplanar A−D−A structured organic small-molecule semiconductor with non-fused ring structure π-bridge, namely B2TPR , and applied it as donor material in OSCs. Owing to the strong electron-withdrawing effect of the end group and the coplanar π-bridge, B2TPR exhibits a low-lying highest occupied molecular orbital and strong crystallinity. Furthermore, benefiting from the coplanar molecular skeleton, the high hole mobility, balanced charge transport and reduced recombination were achieved, leading to a high fill factor (FF). The OSCs based on B2TPR : PC₇₁BM blend film (w/w=1 : 0.35) demonstrates a moderate power conversion efficiency (PCE) of 7.10 % with a remarkable V_oc of 0.98 V and FF of 64 %, corresponding to a low fullerene content of 25.9 % and a low E_loss of 0.70 eV. These results demonstrate the great potential of small-molecule with structure of B2TPR for future low-cost organic photovoltaic applications.     

Effect of heat-pretreatment of the graphite rod on the quality of SWCNTs by arc discharge

Single-walled carbon nanotubes (SWCNTs) have been synthesized in high yield by the dc arc discharge technique under heat-pretreatment of the graphite rod conditions. Before executing arc discharge, the graphite rods containing the catalysts were heat treated at 600, 700, 800 and 900 °C for 1–3 h, respectively. Effects of heat-pretreatment of the graphite rod on the quality of SWCNTs by arc discharge were investigated. The heat-treatment temperature and time were found to be crucial for a high yield of high-purity SWCNTs. Optimum parameter was found to be at the heat-treatment temperature of 800 °C for 2 h. The SWCNTs synthesized under the optimum condition have better field-emission characteristics. The turn-on field needed to produce a current density of 10 μA/cm² is found to be 1.9 V/μm and the threshold field where current density reaches 10 mA/cm² is 3.9 V/μm.     

Microstructure and Optical Properties of AgxO Prepared by Direct-Current Magnetron-Sputtering Method

Two series of AgxO films are prepared on glass substrates by dc magnetron-sputtering method at room temperature and 90℃ under different oxygen to argon gas ratio （OAR） conditions. The mierostrueture is investigated by XRD and SEM in order to obtain the information on the component evolution of AgO＋Ag2O to Ag2O. Its optical properties are investigated by reflectance and absorption spectroscopy to extract the information on metallic and dielectric behaviour evolution of Ag2O, AgO and silver particles and the interband transition. The results indicate that the AgxO film prepared at room temperature is mainly made up of AgO and Ag2 O clusters while Ag2O is the primary component of AgxO prepared at 90℃. The AgxO film mainly consisting of the primary component shows indirect interband transition structure occurring at 2.89eV. Combination of increasing OAR and substrate temperature is an effective method to lower the threshold of thermal decomposition temperature of AgxO and to deal with the bottleneck of short-wavelength optical and magneto-optieM storage.