取代基对醌的结构及电子转移能力的影响

用半经验的AM1,abinitio(HF/3-21G,HF/6-31G^*),及密度泛函[B3LYP/6-31G^*,B3LYP/6-311G(d,p)]方法对1,4-苯酯及其阴离子的结构与性质进行了研究。在此基础上用AM1及BLYP/6-31G(d,p)方法对泛醌Q~0,用AM1方法对泛醌Q~1,泛醌Q~2及其阴离子的结构与性质进行了研究。研究结果表明,由于取代基的影响,泛醌的环平面发生了扭曲,环上原子不再位于同一平面上。结构的变化导致了电子分布发生了变化,并由此导致了偶极矩随6位上取代基的增大而增大。随着6位支链的增长,泛醌的电离势逐渐减小而电子亲和势逐渐增大,泛醌传递电子的能力增强。在上述研究的基础上,对1,4-苯醌及泛醌的自交换电子转移反应过程进行了过程,计算了反应的内重组能,溶剂重组能及电子转移速率常数。结果表明内重组能的大小与取代基的长短无直接关系,而与得电子前后醌的结构变化程度密切相关。除高频振动的变化外,低频振动的变化对内重组能也有显著的贡献。计算所得1,4-苯醌自交换电子转移反应速率常数与实验值相符得很好。     

具有长侧碳链的苯醌类化合物在LB膜上的电化学行为

用LB膜技术将含有长侧碳链的泛醌或质体醌类似物转移到导电玻璃上，用循环伏安法研究了它们的电化学行为．发现醌环上的取代基对其电化学行为有明显影响，提出了泛醌类似物和质体醌类似物在LB膜上的具体电化学过程．     

噻吩甲酰三氟丙酮(TTFA)抑制琥珀酸泛醌还原酶的双位点性质

Dixon作图法和双倒数作图法都表明TTFA有两个抑制位点.低浓度下(0-20μmol/L)的高亲和位点对Q_2呈非竞争性,高浓度下(20μmol/L以上)的低亲和位点呈竞争性.由此得出结论:泛醌还原的两步反应均被TTFA抑制,低浓度时只抑制后半步从半醌还原成氢醌的反应,高浓度时对从泛醌到半醌以及半醌到氢醌两个半反应都抑制.     

天然产物色胺酮及其衍生物合成的研究进展

综述了色胺酮及其衍生物的合成方法。大部分方法都是以吲哚醌和吲哚酮为起始原料,其中吲哚醌和靛红酸酐反应合成色胺酮及其衍生物的方法较为理想。由于色胺酮类化合物具有很好的抗癌、杀菌和消炎等生物活性,新的简捷、低成本合成方法的开发仍然是必要的。     

布帕伐醌的改进合成方法

布帕伐醌是一种治疗牛泰勒焦虫病的药物,其传统的合成工艺存在产率低、污染严重以及成本过高的问题。本文在目前布帕伐醌的合成工艺上进行了优化,以1,4-萘醌作为起始原料,经过4步转化合成得到布帕伐醌,反应总收率达到62%,产品纯度可达99%以上,该方法在布帕伐醌的大规模生产上具有很好的应用前景。     

具有avarane骨架结构的Dysidea属海绵来源的倍半萜醌/氢醌类天然产物的合成研究进展

将具有avarane骨架结构的Dysidea属海绵来源的倍半萜醌/氢醌类天然产物按照连接醌/氢醌部分和倍半萜部分的键的差异分为三类,并以关键的合成策略为线索,分别对目前已报道的这三类倍半萜醌/氢醌类天然产物的合成方法进行了较为详细的阐述,期望能对其他天然产物的合成研究提供帮助.     

带有长侧链醌类化合物的Langmuir膜及其表面电势

泛醌(Ubiquinone)和质体醌(Plastoquinone)作为非蛋白电子载体存在于动物线粒体呼吸链和植物光合作用链中.这两类物质在生物膜上有活性.     

醌类衍生物全反式合成方法研究进展

醌类衍生物是生命体活动中的重要物质,但是醌类衍生物只有其反式异构体才有生理活性,所以如何实现醌类物质的全反式合成,是其合成研究的热点.二十世纪六十年以来,具有生物活性的醌类衍生物合成的研究不断深入,并取得了很大的进展.作者就醌类衍生物的全反式合成做一概述.     

哌嗪酮取代醌类衍生物的简便合成

建立了一锅法合成哌嗪酮取代醌类衍生物的方法.该方法以哌嗪酮烯胺酯为合成砌块,以乙腈为溶剂,醋酸作催化剂,在室温条件下,通过哌嗪酮烯胺酯1与醌类化合物2的α-C选择性烷基化反应,再经氧化脱氢简洁高效地合成了一系列结构新颖的哌嗪酮醌类衍生物3a~3l,产率70%~88%.该方法具有原料易得、合成路线简洁、产率高和操作简便等特点.     

可见光诱导无金属条件下交叉脱氢偶联反应合成醌类苄基化衍生物

苄基化醌类化合物广泛存在于天然产物及药物活性分子中,对其进行简单高效的合成具有重要价值,目前已有的醌类苄基化反应条件都较为苛刻.介绍了一种以有机染料亚甲基蓝作为光敏剂,叔丁基过氧化氢作为氧化剂,在可见光照射条件下通过醌与甲苯衍生物之间的交叉脱氢偶联反应实现醌类化合物直接苄基化的新方法.该方法具有条件温和、底物范围广泛、官能团兼容性好、成本低廉及能有效避免金属残留等诸多优势.该方法的建立为醌类活性分子的合成及衍生化提供了新的思路和途径.     

Combining enabling techniques in organic synthesis: continuous flow processes with heterogenized catalysts

The concepts article describes enabling techniques (solid-phase assisted synthesis, new reactor design, microwave irradiation and new solvents) in organic chemistry and emphasizes the combination of several of them for creating new synthetic technology platforms. Particular focus is put on the combination of immobilized catalysts as well as biocatalysts with continuous flow processes. In this context, the PASSflow continuous flow technique fulfils both chemical as well as chemical engineering requirements. It combines reactor design with optimized, monolithic solid phases as well as reversible immobilization techniques for performing small as well as large scale synthesis with heterogenized catalysts under continuous flow conditions.     

3D Graphene Foam by Chemical Vapor Deposition: Synthesis,Properties, and Energy-Related Applications

In this review, we highlight recent advancements in 3D graphene foam synthesis by template-assisted chemical vapor deposition, as well as their potential energy storage and conversion applications. This method offers good control of the number of graphene layers and porosity, as well as continuous connection of the graphene sheets. The review covers all the substrate types, catalysts, and precursors used to synthesize 3D graphene by the CVD method, as well as their most viable energy-related applications.     

Chemical reaction and Soret effects on MHD convective flow of second grade fluid through an absorbent medium with ramped wall temperature as well as ramped surface concentration

In the present paper, the heat generating and/or absorption as well as thermo-diffusion on the unsteady free convection MHD gyrating flow of radiation and chemical reactive second grade fluid past an unbounded perpendicular plate during absorbent medium have been discussed. Here, it is assumed that, the confining plate has the ramped wall temperature with ramped surface concentration and isothermal temperature with ramped surface concentration. The analytical solutions for the governing equations are found by utilization of Laplace transformation methodology. The velocity, temperature and concentration profiles are analyzed with quite few figures. It is determined that, velocity, temperature and concentration distribution sketches in case of ramped temperature as well as ramped surface concentration are not as much of as those of isothermal temperature as well as ramped surface concentration. In addition to the idioms of skin friction, Nusselt number as well as Sherwood number are achieved and characterized numerically with tabular format.     

基于杯芳烃主体的分子自组装研究进展

分子自组装是超分子化学最重要的研究内容之一. 杯芳烃作为继冠醚、环糊精之后的第三代人工合成受体分子已在分子自组装研究方面取得了重要进展并显示了广泛的应用前景. 主要综述杯芳烃衍生物通过氢键、金属诱导配位、π-π作用、疏水作用等非共价键弱相互作用力在溶液状态、固态和界面的分子自组装方面的研究进展.     

Nitraza-/Oxa-Propylene- and Hydrazonemethylene-Bridged 1,2,4-Nitraminotriazoles and Selected Salts

Two new bridged nitraminotriazoles with bridging oxapropylene and nitrazapropylene moieties were synthesized, and converted into several salts, as well as from the hydrazonemethylene bridged nitraminotriazole. All compounds were fully characterized by NMR and IR spectroscopy, elemental analysis as well as differential thermal analysis. The sensitivity towards friction and impact were determined according to BAM standard technics and the energetic properties were calculated by using the EXPLO5 computer code. The neutral compounds as well as the various salts were examined in terms of their physicochemical properties and detonation performance to each other and compared to the commonly used secondary explosive RDX.     

The determination of trace metals in lubricating oils by atomic spectrometry

The determination of trace metals in lubricating oils using atomic spectrometric methods is reviewed. The importance of such analyses for technical diagnostics as well as the specific sample characteristics related to the analyte form (metallo-organic and metal particles) is discussed. Problems related to sample pre-treatment for appropriate sample introduction and calibration are addressed as well as the strategies to overcome them. Recent trends aimed at simplifying sample manipulation are presented. The applications and scope of AAS, ICP OES and ICP MS techniques for the determination of trace metals in lubricating oil is individually discussed, as well as some present instrumental trends.     

Modification of aqueous polyurethanes by forming latex interpenetrating polymer networks with polystyrene

A series of latex particles with interpenetrating polymer network structure have been synthesized from waterborne polyurethane (PU) and polystyrene (PS). The effect of PU/PS composition, cross-linking density in the PS domain as well as in PU have been studied in terms of dispersion size, transmission electron microscopy morphology, mechanical and dynamic mechanical properties in addition to swellability in water and toluene of the dispersion cast film. It was found that inverted core (PS)–shell (PU) morphology was well defined and that the domain size as well as the film properties were well controlled by the latex composition and cross-linking density of both phases. Received: 15 March 2000 Accepted: 21 February 2001     

Two-mode Fluorescent Detection of Cyanide by a Simple AIE-based Chemosensor with Red Emission

TPE-TCF, a simple TPE-derivative with red-emission was used to detect cyanide in the condition of single dispersion as well as under aggregate state. It could be found that TPE-TCF exhibited excellent fluorescent response to cyanide in both situations, and the mechanism was supposed to be the reaction between cyanide and the double bond in TPE-TCF as well as the aggregation induced emission property of the reacted TPE-TCF molecules. What's more, TPE-TCF could distinguish cyanide with other species, such as common anions and biotiol well, which indicated it as a potential indicator for cyanide with good selectivity and specificity.     

Theory and practice of a powerful technique for electrochemical investigation of solid solution electrode materials

The theory and practice of a solid-state electrochemical technique which allows measurement of the chemical diffusion coefficient and partial conductivities of the mobile species in a mixed ionic-electronic conductor, as well as the equilibrium partial thermodynamic quantities, are described. The theory incorporates nonideal thermodynamic behavior of the carriers as well as cross terms in the flux equations. Once the cell is assembled, all parameters can be measured as a function of composition without any further physical manipulation, so that the experiments are well suited to automatic control.     

光诱导钌配合物的几何异构和结构异构反应研究进展

金属钌(Ru)的配合物具有丰富的基态和激发态的光物理、光化学性质,在太阳能转换、光催化以及分子识别等方面都得到了广泛深入的研究.光诱导的钌配合物的异构反应是其颇具特色的一类光反应,研究光异构反应对于光能量转化、信息储存以及"分子光开关"和"分子马达"的设计具有重要的意义.本文小结和综述了钌配合物的光诱导几何异构和结构异构反应的特性和机理以及最新的研究进展.