1,4—二氟四苯基苯的合成,结构与构象

借助电子转移催化反应的方法，用电子给予体１，４－二锂四苯基丁二烯将惰性的三溴氟甲烷活化，并与之发生反应。产物１，４－二氟四苯基苯的结构经ＭＳ、ＮＭＲ和Ｘ射线单晶衍射确证，并以分子力学的方法对其进行了构象分析。     

四苯基卟啉质子化结构变化的理论研究（Ⅱ）－－五氟苯基及吡咯环上氟的取代基效应

卟啉的衍生物在DNA螺旋中的嵌入并堆积具有高选择性。为考察5，10，15，20－四（五氟苯基）卟啉（TF5PPH2）和2，3，7，8，12，13，17，18－八氟－5，10，15，20－四（五氟苯基）卟啉（F28TPPH2）中F取代基对质子化卟啉结构的影响，在四苯基卟啉研究的基础上，用半经验的AM1 MO方法，并进行合理的对称性限制，计算了TF5PPH2和F28TPPH2及其质子化二酸（TF5PHH4^2 ）和（F28TPPH4^2＋）的几种可能的构型。结果表明，由于F取代基的影响，质子化过程中的结构、键电荷布居和前线分子轨道均有明显的变化，二者的质子化二酸与溶液质子的快速交换作用也都变得更加困难。     

含氟杀菌剂5-氯-2，4，6-三氟-1，3-苯二腈的合成

1　前言2 ,4,5 ,6-四氯 -1 ,3 -苯二腈 ,俗名百菌清 ( 1 ) ,是一种广谱、高效、安全的农林及工业用杀菌剂 ,对多种作物具有预防和治疗作用 ,其持效期长且稳定 ,可用于麦类、水稻、果树、蔬菜、花生、茶叶、橡胶、森林等多种作物的各种病害 ,还可以用于防治蚕体酵母霉病和僵病及制革等工业防霉[1] 。国内有云南化工厂等 1 8家工厂生产其原药、粉剂或乳油。其含氟衍生物研究尚不多 ,由于氟原子或含氟基团的导入 ,使化合物的挥发性、扩散性、相溶性及表面活性增加 ,而位阻影响不大 ,故能充分发挥在有机体内的脂溶性 ,对生物体的多种相态、对膜…     

3,3'-二磺酸钠4,4'-二氟苯砜的合成

在高氯酸钠催化下,氟苯与氯化亚砜反应制得4,4'-二氟二苯亚砜(2);2经H2O2氧化制得4,4'-二氟二苯砜(3);3用发烟硫酸磺化合成了3,3'-二磺酸钠4,4'-二氟苯砜,总收率57%.其结构经1H NMR确证.     

相转移催化法合成N，N＇－二芳基－1，4－苯二氧基二乙酰胺

于液－液相转移催化条件下，以ＰＥＧ－４００为催化剂，通过１，４－苯二氧基二乙酰氯与芳胺反应，合成了相应的酞胺３ａ～３０。     

基于六苯基苯骨架四苯基乙烯衍生物的合成及聚集诱导发光性质研究

设计合成了三个基于六苯基苯骨架结构的四苯基乙烯衍生物HPB-nTPE (n=2, 4, 6), 它们的分解温度均在440 ℃以上, 具有很好的热稳定性. 研究了化合物的均相溶液、聚集体以及固体粉末的光物理性质. 该类化合物具有典型的聚集诱导发光性质, 在均相溶液中几乎不发光, 而形成聚集体后发出明亮的蓝绿色荧光, 荧光量子产率分别为0.37, 0.36和0.37, 与均相溶液中相比增强了400多倍. HPB-nTPE固态呈无定形结构, 荧光量子产率分别为0.39, 0.36和0.36, 约为固态四苯基乙烯的1.8倍. HPB-nTPE的聚集态和固态的高发光量子产率来自两方面的贡献, 一是凝聚态抑制了四苯基乙烯基团中苯环的自由旋转引起的激发态非辐射跃迁, 另一方面是星形刚性六苯基苯骨架进一步抑制了凝聚态分子内和分子间四苯基乙烯基团π-π堆积引起的激发态非辐射跃迁过程, 从而提高了四苯基乙烯基团的辐射跃迁效率. 本研究对高效有机光功能材料的发展有重要意义.     

N-[4-(三氟甲氧基)苯基]氨基甲酸苯酯的合成

以三氟甲氧基苯为起始原料,经硝化、加氢还原和酰化反应合成了N-[4-(三氟甲氧基)苯基]氨基甲酸苯酯,总收率84.6%,纯度98.9%,其结构经¹H NMR和MS（ESI）确证。     

四苯基吡嗪的微波合成

在乙酸酐存在下,苯偶姻与乙酸铵进行缩合反应,选择性地合成了2,3,5,6-四苯基吡嗪,产率51%;在微波辐射下反应6 min～10 min,产率可以提高到68%.其结构经1H NMR和IR表征.     

O，O′－2，2′－联苯基，S－苄基二硫代磷酸酯分子的构象研究

本文用ＡＳＥＤ－ＭＯ法研究了Ｏ，Ｏ′－２，２′－联苯基，Ｓ－苄基二硫代磷酸酯单个分子的构象，得到４种低能构象。分析了常温下４种构象的分布，稳定构象之间的转化以及与晶态分子构象之间的关系．     

含4，4＇－二羟基二苯酮热致液晶四元共聚酯的合成与表征

含４，４＇－二羟基二苯酮热致液晶四元共聚酯的合成与表征董德文，韩平，倪玉山，丁孟贤，韩伟（中国科学院长春应用化学研究所长春１３００２２）（吉林化工学院化工系吉林）关键词　热致液晶，共聚酯，向列型，二羟基二苯酮关于热致液晶芳香族聚酯的研究已有大量的报道...     

顺式环十二碳烯的构象

用分子力学法(MMX程序)计算了15-苯基双环[10,3,0]十五碳-1(12)-烯-13-酮,其分子中环十二碳烯部分的构象为能量最低的[l_(ene)2333],与X衍射结果吻合.同时,还计算了15个顺式环十二碳烯的构象,求出了它们的能量及结构参数,讨论了影响构象稳定性的因素.     

味觉化合物的构象与活性的关系

味觉化合物的构象与活性的关系许禄,姚喻元（中国科学院长春应用化学研究所应用谱学开放实验室,长春,１３００２２）关键词味觉化合物,分子力学,构象分析分子结构和味觉的相关性是一个非常活跃的研究领域,许多人从不同的侧面进行这方面的研究,并总结出一定的规律［...     

间位聚苯及其衍生物的构象与电子结构的理论研究

用分子力学方法(MM)对间位聚苯(PMP)及其衍生物的势能随扭曲角(f)变化规律进行了研究.结果表明，势能曲线上出现四个能量最小值，分别对应于扭曲角f ≈－135°,－45°,45°,135°.进一步对以上构建的全部PMP及其衍生物用分子力场Drieding 2.11进行了分子力学能量优化.最终得到主要的四种构象，其中螺旋构象的能量最低，而且以螺旋构象为优势分布构象.在真实条件下，PMP及其衍生物长链可能采取以上四种构象的混合片段组成.用量子化学方法(GGA-DFT)研究了PMP及其衍生物的电子结构能隙随相邻苯环之间的扭曲角的变化趋势.用量子化学半经验方法(AM1)对四种构象分别进行几何优化，优化结果与分子力学优化结果基本一致，并运用混合密度泛函方法(DFT/B3LYP/6-31G)进一步对AM1优化的构象结构进行更精确的电子结构能隙计算.最终得出影响间位聚苯及其衍生物电子结构能隙的主要因素为连接苯环间扭曲角的大小.     

单嘧磺隆晶体-活性构象转换的分子动力学模拟

应用分子动力学模拟方法对单嘧磺隆在水、正辛醇和正辛烷3种不同溶剂中的构象行为、单嘧磺隆与3种溶剂之间的相互作用能及氢键相互作用进行了计算研究. 计算结果表明, 在3种不同的溶剂中, 单嘧磺隆的优势构象不同; 其构象转换过程, 特别是转换成活性构象的过程主要发生在水溶液中; 与溶剂分子间的相互作用是分子构象行为的决定因素; 单嘧磺隆的脲桥部分可以和含氢键接受体的溶剂形成氢键, 分子间与分子内氢键的竞争可能是从晶体构象转换成活性构象的主要驱动力.     

对叔丁基杯[6]-1,4-2,5-双冠醚的合成、构象及其对阳离子的识别性能研究

采用分步法高产率地合成了系列新型对叔丁基杯[6]双冠醚，并得到了除杯式与1，2，3－交替式构象之外的第3种稳定构象的杯[6]衍生物：1，4－交替式杯[6]-1,4-2,5-双冠醚。研究了它们对碱金属及脂肪胺离子的两相萃取性能，发现杯[6]双冠醚具有与杯[6]单冠醚不同的识别能力。     

Crystal Structure and Conformation of a Dipyrrylmethane. The gem-Dimethyl Effect

Summary.  A crystal structure determination of the new dipyrrylmethane diethyl-2,3,5,5,7,8-hexamethyl-5,10-dihydrodipyrrin-1,9-dicarboxylate (1) is only the third reported for a dipyrrylmethane and the first with a gem-dimethyl group at the bridging carbon atom. Conformation determining torsion angles are compared to those from molecular mechanics calculations and to the corresponding data for an analogous dipyrrylmethane (2) with no gem-dimethyl moiety. The crystal structures of 1 and 2 differ significantly: 1 adopts the +ac,+ac or −ac,−ac conformation, whereas 2 exists in the −ac,+sc conformation in an intermolecularly hydrogen bonded dimer. There is no evidence for hydrogen bonding in crystals of 1, and its ac conformation is unlike that found about the central core of bilirubin (sc,sc). Taken collectively, the data indicate that the presence of a sterically demanding and potentially conformation distorting gem-dimethyl group located at the bridging carbon of a dipyrrylmethane (i) stabilizes a conformation that brings the pyrrole NH groups syn to the gem-dimethyls and (ii) would destabilize the ridge-title conformation of 10,10-dimethylbilirubin. Received December 3, 1999. Accepted December 15, 1999     

Synthesis,Structure, and Conformation of 2′,3′‐Fused Oxathiane and Thiomorpholine Uridines

The syntheses of two 2′,3′‐fused bicyclic nucleoside analogues, i.e., 1‐[(4aR,5R,7R,7aS)‐hexahydro‐5‐(hydroxymethyl)‐4,4‐dioxidofuro[3,4‐b][1,4]oxathiin‐7‐yl]pyrimidine‐2,4(1H,3H)‐dione ( 1a ) and 1‐[(4aS,5R,7R,7aS)‐hexahydro‐7‐(hydroxymethyl)‐1,1‐dioxido‐2H‐furo[3,4‐b][1,4]thiazin‐5‐yl]pyrimidine‐ 2,4(1H,3H)‐dione ( 1b ), are described, the key step being an intramolecular hetero‐Michael addition. Their structures and conformations, previously solved by X‐ray crystallography, were analyzed in more detail, using 1D‐ and 2D‐NMR as well as HR‐MS analyses.     

Conformation of 1,2-Dimethoxyethane in Water

To understand the conformation of 1,2-dimethoxyethane (DME) in water, a system of two kinds of molecules, DME and H_2O, was focused. The interaction of various conformers of DME with water was studied by means of ab initio molecular orbital calculation with 6-31G (d) basis set. It is shown that there are two forms of interactions between the two molecules in the system, the close touched (H_2O attaches to the two oxygen atoms of DME) and the open touched (H_2O attaches to one oxygen atom of DME) structures. The conformation of DME is remarkably influenced by the interactions. Instead the ttt conformer is preferred in the gas state, with a close touched H_2O the tgt conformer becomes the most stable one. The obtained hydration energies show that the stabilized order of DME conformers by water is tgt>tgg′>ttt.     

Non-Covalent Interactions Enforce Conformation in Switchable and Water-Soluble Diketopiperazine-Pyridine Foldamers

To reach their potential as mimics of the dynamic molecules present in biological systems, foldamers must be designed to display stimulus-responsive behavior. Here we report such a foldamer architecture based on alternating pyridine-diketopiperazine linkers. Epimerization is conveniently prevented through a copper-catalyzed coupling protocol. The compounds’ native unswitched conformation is first discovered in the solid and solution state. The foldamers can be solubilized in DMSO and pH 9.5 buffer, retaining conformational control to a large degree. Lastly, dynamic switching is demonstrated through treatment with acid, leading to behaviour we describe as stimulus-responsive sidechain reconfiguration.     

Locking the Conformation of a Paddlewheel Rhodium Complex: Design,Synthesis, and Applications in Catalytic Nitrene Transfers

The exponential proliferation of conformers makes it impossible to examine the entire population in most systems. Controlling conformational ensembles is thus pivotal in many areas of chemistry. Rh₂(esp)₂, a dicarboxylate-derived paddlewheel rhodium complex, is one of the most effective catalysts for nitrene chemistry. Its enormous success has led to preparing many analogous complexes. However, there has been little consideration for the conformational dynamics of the parent catalyst. Herein, we report a new ligand modification principle that prevents conformer interconversion. The resulting complex comprises two isolable conformers, whose structures have been determined by X-ray diffraction. Combined experimental and computational data has revealed similarities and dissimilarities between the conformationally confined and parent complexes. Three model cases have demonstrated the utility of conformational fixation in the development of stereoselective catalysts for nitrene transfer reactions. The design principle described in this study can be combined with other established modification strategies, serving as a springboard for further advancement of the chemistry of paddlewheel metal complexes.