1,7,10,16—四氧—4,13—二氮杂—N,N‘—二苄基环十八烷对金属离子的识别作用

１，７，１０，１６┐四氧┐４，１３┐二氮杂┐Ｎ，Ｎ′┐二苄基环十八烷对金属离子的识别作用王利亚陈朝晖金林培＊（北京师范大学化学系１００８７５）关键词苄基冠醚稀土配合物晶体结构离子识别ＫｅｙｗｏｒｄｓＢｅｎｚｙｌ－ｃｒｏｗｎＲａｒｅｅａｒｔｈｃｏｍｐｌ...     

两种新型手性冠醚聚硅氧烷用于毛细管气相色谱法分离对映体

两种新型手性冠醚聚硅氧烷用于毛细管气相色谱法分离对映体周喜春，严慧，吴采樱，陈远荫（武汉大学化学系武汉４３００７２）手征性冠醚是在大醚环上兼连有手征性中心的冠醚。由于手性中心的引入，使其对客体分子具有独特的结构选择性和手征性选择。我们在多年研究冠醚聚...     

查尔酮冠醚PVC膜钾离子选择性电极的初步研究

查尔酮冠醚ＰＶＣ膜钾离子选择性电极的初步研究李廷盛，蔡汉临，王传林，张建明，魏旭东，胡宏纹（华中师范大学化学系武汉４３００７０））（南京大学化学系南京）关键词查尔酮冠醚ＰＶＣ膜，钾离子电极，性能钾离子在生物细胞膜内外的浓度梯度对生物膜的能量传输等起着...     

两种新型手性冠醚聚硅氧烷用于毛细管气相色谱法分离对映体

 两种新型手性冠醚聚硅氧烷用于毛细管气相色谱法分离对映体周喜春，严慧，吴采樱，陈远荫（武汉大学化学系武汉４３００７２）手征性冠醚是在大醚环上兼连有手征性中心的冠醚。由于手性中心的引入，使其对客体分子具有独特的结构选择性和手征性选择。我们在多年研究冠醚聚硅氧烷固定液的基础上，设计合成了两种含末端烯基的手性冠醚，并采用硅氢加成技术将其键合在聚硅氧烷链上，制得了两种高分子化的手性冠醚固定相，并初步考察了其气相色谱性能。研究结果表明：这两种手性冠醚裹硅氧烷固定液均具有普通冠醚聚硅氧烷固定液的良好柱性能.。     

氮杂冠醚研究Ⅶ、双仲胺型氮杂冠醚对过渡金属离子的选择性萃取作用

合成了五种新型双仲胺型氦杂冠醚，研究了它们对过渡金属离子进行液—液萃取，并用原子吸收法测定其浓度。实验结果表明：这类冠醚对Ａｇ￣＋、Ｐｄ￣（２＋）、和Ｐｔ￣（４＋）等贵金属离子有较强的选择配位性能，对选择性分离这些金属离子有重要的意义。     

冠醚的空腔及其与希土硝酸盐配合物结构的关系

本文计算了五十多种希土硝酸盐冠醚配合物中冠醚的空腔直径Ｄｃ及希土离子直径（Ｄｉ）与Ｄｃ之比值（Ｄｉ／Ｄｃ）．冠醚的空腔受许多因素影响．诸如希土元素的离子半径，希土离子与冠醚之间的结合力，冠醚环上的取代基等．Ｄｉ／Ｄｃ数值所处的范围与所形成的配合物结构类型密切相关，遵循下列四个近似规则：（１）如Ｄｉ／Ｄｃ＞１．４，所形成的配合物结构中三个阴离子占据冠醚的同一侧（结构类型Ⅰ）；（２）若０．８＜Ｄｉ／Ｄｃ＜０．９，配合物中金属离子被包围在冠醚空腔中．三个阴离子占据冠醚环的两侧（结构类型Ⅱ）；（３）如Ｄｉ／Ｄｃ＜０．８，配合物中冠醚分了一般与配位水分子以氢键相连（结构类型Ⅲ）；（４）若０．９＜Ｄｉ／Ｄｃ＜１．４，配合物一般为结构类型Ⅲ，在某些情况下也可为结构类型Ⅳ，它由几个配位阴离子及一个多硝酸根配阴离子形成．     

萃取法研究Cu~（2＋）－bpy－PCA~－体系有机配体间的芳环堆积作用

萃取法研究Ｃｕ~（２＋）－ｂｐｙ－ＰＣＡ~－体系有机配体间的芳环堆积作用徐景华，龚钰秋，黄宪（杭州大学化学系杭州３１００２８）关键词芳环堆积作用，铜，联吡啶，苯基羧酸可用ｐＨ电位滴定、质子核磁共振、电子光谱和ＣＤ光谱、萃取等方法研究混配配合物配体间的芳...     

喹啉基氮杂大环铜,镍配合物的结构和性质差异

喹啉基氮杂大环铜、镍配合物的结构和性质差异安道利，卜显和，李金亮，陈荣悌（南开大学化学系，天津３０００７１）二氧四胺大环配体是Ｃｕ￣（２＋）、Ｎｉ￣（２＋）、Ｃｏ￣（２＋）、Ｐｔ￣（２＋）等金属离子的优良配体，它们同时具有饱和大环多胺和寡聚肽的结构特...     

含氮杂冠醚结构单元的吲哚啉螺苯并吡喃的合成和性质

含氮杂冠醚结构单元的吲哚啉螺苯并吡喃的合成和性质伍新燕吴成泰＊（武汉大学化学系武汉４３００７２）关键词氮杂冠醚，螺吡喃，合成，性质１９９７－０６－０５收稿，１９９７－１２－０８修回国家自然科学基金和国家教委博士点专项基金资助项目含冠醚结构单元的吲哚啉...     

以AmberlystA－27为载体的光纤铁反射传感器的研究

以ＡｍｂｅｒｌｙｓｔＡ－２７为载体的光纤铁反射传感器的研究卢建忠，章竹君（南京大学化学系，南京，２１０００８）（陕西师范大学化学系，西安，７１００６２）关键词光纤传感器，反射，铁离子金属离子光纤传感器的设计是基于固定在探头上的指示剂与溶液中金属离子之...     

Synthesis of Eight Nitrogen‐Pivot Benzo‐aza‐lariat Crown Ethers

A short and convenient synthesis of two series of eight totally new lariat crown ethers is reported in this article. These lariat ethers are derived from triaza‐dibenzo‐27‐crown‐7 and diaza‐dibenzo‐27‐crown‐7 through condensation of appropriate aza‐crown ethers with appropriate substituted compounds in chloroform. The substituted reagents are acetic anhydride, benzoyl chloride, phthalic anhydride, and butanedioic anhydride, respectively.     

Enhanced activity of α-chymotrypsin in organic media using designed molecular staples

We report the enhancement of α-chymotrypsin activity in organic solvents using modified peptides bearing two crown ethers. The transesterification of N-acetyl-l-phenylalanine ethyl ester with 1-propanol was used as model reaction. Co-lyophilization of crown ether modified peptides with α-chymotrypsin prior to use resulted in an increase of enzyme catalytic activity in non-aqueous media. The efficiency of enzyme activation is dependent on the amino acid sequence of peptidic additives and on the positions of the amino acids bearing the crown ligand.     

Reaction of Amino Acid Salts with 4-Nitrophenyl Acetate under Solid-Liquid Phase Transfer Conditions

The reaction of amino acid salts with 4-nitrophenyl acetate in a system consisting of a solid phase and organic solvent with catalysis by crown ethers and quaternary onium salts may be carried out both on the phase separation surface and in the organic phase depending on the nature of the participants in the phase transfer catalysis reaction.     

The complexation of alkali metal ions by crown ethers,aza crown ethers,and cryptands in propylene carbonate

The reactions between alkali metal ions and crown ethers, aza crown ethers, and cryptands in propylene carbonate were studied by potentiometric and calorimetric titrations. The most stable complexes formed by macrocyclic and macrobicyclic ligands are when the ligand and cation dimensions are comparable. On comparing the complex stabilities of crown ethers and aza crown ethers of the same size, crown ethers were, on the whole, found to form the most stable complexes, with the exception of the lithium cation. Enthalpic factors are responsible. Substitution of the amino group protons of the aza crown ethers by benzyl groups leads to a high increase in values of the reaction enthalpy. This effect is partly compensated by entropic contributions. The bulky benzyl groups reduce the ligand solvent interactions and induce a ligand conformation with the lone pair of electrons from the nitrogen donor atoms which are more or less directed inside the cavity. The thermodynamic data for the transfer from methanol to propylene carbonate indicate that the ligands containing nitrogen show specific interactions with methanol.This paper is dedicated to Professor H. Strehlow on the occasion of his 70th birthday.     

Komplexierungseigenschaften von Pyridinokronenethern gegenüber Alkali- und Erdalkaliionen in Methanol

Complexing Properties of Pyridino Crown Ether with Alkali and Alkali-Earth Cations in Methanol The stability constants and thermodynamic values of the complex formation of several pyridino crown ethers with alkali and alkaline-earth cations were determined by calorimetric titration in methanol. The stability of the complexes is lower than with crown ethers. This is mainly caused by a decrease of reaction enthalpies. Compared with other mono substituted crown ethers the complexes with pyridino crown ethers are fare more stable due to entropic effects. With increasing cavity size the stability constants, enthalpies and entropies for the reaction of crown ethers and pyridino crown ethers approach similar values.     

Capillary electrophoresis separation of peptide diastereomers that contain methionine sulfoxide by dual cyclodextrin‐crown ether systems†

A dual‐selector system employing achiral crown ethers in combination with cyclodextrins has been developed for the separation of peptide diastereomers that contain methionine sulfoxide. The combinations of the crown ethers 15‐crown‐5, 18‐crown‐6, Kryptofix® 21 and Kryptofix® 22 and β‐cyclodextrin, carboxymethyl‐β‐cyclodextrin, and sulfated β‐cyclodextrin were screened at pH 2.5 and pH 8.0 using a 40/50.2 cm, 50 μm id fused‐silica capillary and a separation voltage of 25 kV. No diastereomer separation was observed in the sole presence of crown ethers, while only sulfated β‐cyclodextrin was able to resolve some peptide diastereomers at pH 8.0. Depending on the amino acid sequence of the peptide and the applied cyclodextrin, the addition of crown ethers, especially the Krpytofix® diaza‐crown ethers, resulted in significantly enhanced chiral recognition. Keeping one selector of the dual system constant, increasing concentrations of the second selector resulted in increased peak resolution and analyte migration time for peptide‐crown ether‐cyclodextrin combinations. The simultaneous diastereomer separation of three structurally related peptides was achieved using the dual selector system.     

The synthesis of unique structures of tetra-crown ethers through Michael addition

Unique structures of tetra-crown ethers were successfully synthesized by the reaction of tetramethylolmethane tetraacrylate (TMMT) reacted with crown ethers containing primary amine functional group such as 2-aminomethyl crown ethers and 4-aminobenzo crown ethers; containing secondary amine group like 1-aza crown ethers through Michael reaction. The newly synthesized tetra-crown ethers were characterized by ¹H NMR, ¹³C NMR, FAB mass spectrum, elemental analyses, IR, respectively.     

Oxidation of organic sulfur compounds with hydrogen peroxide in the presence of crown ethers

Hydrogen peroxide oxidizes methyl phenyl sulfide and benzothiophene in the presence of crown ethers to the corresponding sulfoxides and sulfones. The oxidation is retarded by amino acids. UV and NMR spectroscopies show that, at the initial stage of oxidation, complexation occurs between crown ether, hydrogen peroxide, and sulfide, as well as between crown ether and amino acid.     

Crowning Proteins: Modulating the Protein Surface Properties using Crown Ethers

Crown ethers are small, cyclic polyethers that have found wide‐spread use in phase‐transfer catalysis and, to a certain degree, in protein chemistry. Crown ethers readily bind metallic and organic cations, including positively charged amino acid side chains. We elucidated the crystal structures of several protein‐crown ether co‐crystals grown in the presence of 18‐crown‐6. We then employed biophysical methods and molecular dynamics simulations to compare these complexes with the corresponding apoproteins and with similar complexes with ring‐shaped low‐molecular‐weight polyethylene glycols. Our studies show that crown ethers can modify protein surface behavior dramatically by stabilizing either intra‐ or intermolecular interactions. Consequently, we propose that crown ethers can be used to modulate a wide variety of protein surface behaviors, such as oligomerization, domain–domain interactions, stabilization in organic solvents, and crystallization.     

单氮杂冠醚的合成及性质研究(Ⅱ)──两亲分子的合成及在水溶液中的自组织行为

以酰氯或酸酐与N-(3′-氨苯基)氮杂冠醚反应合成了一系列含长脂链基团的单氮杂冠醚两亲分子。电镜观测结果表明:系列两亲分子在稀溶液中均能自组织稳定的以双分子膜为基本结构的囊泡,其大小为30～150nm,泡壁厚度为5～25nm;并用UV-Vis和微量差示扫描量热研究了双分子膜中分子的聚集态和相变过程。