几种三相催化剂在氰代、碘代和二氯卡宾反应中的催化行为

本工作研究了带含氧冠醚、氮杂冠醚、酚醛型冠醚、开链冠醚的四种聚合物作为三相催化剂在氰代、碘代和二氯卡宾反应中的催化活性,其中以冠醚环上带有叔胺氮原子的氮杂冠醚聚合物催化活性最好。     

我国的冠醚合成化学

我国冠醚工作者已发表冠醚论文540余篇,合成冠醚化合物超过560个,我国冠醚工作者对冠醚化学作出了卓越贡献。本文介绍我国冠醚合成化学的主要成就。 1.冠醚典型冠醚的合成,一般都是沿用Pedersen的经典方法。吴养洁等发明的冠醚合成新方法具有操作简便、反应时间短和成本低等优点。该法已在工厂实现冠醚系列产品的生产。     

基于密度泛函理论研究锂-冠醚复合物的结构和热力学参数

冠醚对碱金属离子具有高选择性,在锂元素的分离富集上有着广泛的应用。本文基于密度泛函理论（DFT）研究了冠醚环大小、取代基种类、配位原子种类和数量等因素对冠醚空间结构和热力学参数的影响。结果表明,苯并冠醚系列中的苯并-15-冠-5具有更好的配位能力,取代基、配位原子对冠醚的络合能力均有一定影响,因此可通过选择合适的冠醚环,引入供电子基团和含氮杂原子等方法来改善冠醚的分离富集能力。这对冠醚体系分离富集锂元素具有重要的指导意义。     

冠醚共缩聚物的合成与性能

双冠醚化合物对某些金属离子比单冠醚具有更好的络合性能和选择性,它们合成、应用研究越来越受到人们的重视,本工作采用2,6-二羟甲基对甲氧基苯酚为缩合剂与芳香族冠醚缩聚,得到一系列具有双冠醚结构特征的新酚醛型聚苯并冠醚(简称聚冠醚),聚冠醚合成容易,并呈现了比相应单冠醚更优越的络合萃取能力和富集效率。     

基于手性冠醚的对映选择性识别研究进展

介绍了冠醚类化合物的结构特点及络合性能、冠醚的络合作用和识别分子的新进展.冠醚类化合物因其稳定的构象和易于修饰的特点,成为研究最为广泛的主体分子之一,其中大量的文献报道了能够用于对映选择性识别和检测的手性冠醚.在分子识别的研究中,核磁、荧光、紫外和质谱是四种最常见的研究方法,总结了近年来手性冠醚运用这四种方法在对映选择性识别领域的最新研究进展并对手性冠醚的发展前景作了展望.     

冠醚菁染料的研究——Ⅰ.冠醚菁染料的合成

Dix等^[1]曾讨论冠醚偶氮染料、冠醚二苯甲烷染料和冠醚三苯甲烷染料的研究结果,关于冠醚菁染料迄今还未见报道.鉴于菁染料发色团之甲川链的可调性[2a]和冠醚空腔大小的可调性^[3],作者设想将菁染料结构因子和冠醚结构因子结合于同一分子之中,可望延伸出一系列富于颜色变化的离子选择性络合的冠醚菁染料;也可能用于分析化学和生物膜的研究等.     

由(+)-2-氨基丁醇合成氮杂手性冠醚

手性冠醚由于具有手性识别和不对称催化有机反应的性质而受到人们的重视,有关它们的合成及性质,已很多论述。氮杂冠醚则是合成穴醚、双冠醚、套索冠醚(LariatEther)等的重要中间体,也可与高分子材料(高分子载体或高分子基质)连接,用于有机化合物的色谱分离。氮杂手性冠醚兼备手性和氮杂冠醚两种特性,而可能具有广泛的用途。     

端烯基液晶冠醚的合成及其性质的研究

合成了端烯基液晶冠醚新化合物,通过紫外光谱、红外和拉曼光谱以及质谱对液晶冠醚的结构进行了详细的分析;并利用差示量热扫描(DSC)方法和热台偏光显微镜研究了液晶冠醚的热性质及织构,探讨了液晶冠醚的结构与相态的关系。     

新型蒽并冠醚的合成及主客体键合行为

以9,10-二溴甲基蒽为原料,经过3步反应合成了2种新型蒽并冠醚;采用核磁共振波谱、紫外光谱和单晶X射线衍射等手段研究了蒽并冠醚与2种π-缺电子客体之间的键合行为.结果表明,蒽并冠醚与客体之间的键合作用主要是π-堆积作用.通过紫外光谱滴定法测得蒽并冠醚与客体之间的键合常数高于经典的苯并冠醚和萘并冠醚,表明蒽结构基团的引入改善了冠醚的主-客体键合能力.     

4′-N-烷基(芳基)-氨甲基苯并-18-冠醚-6及高聚物支载和硅胶支载冠醚的合成

本文报道新冠醚4′-N-烷基-和4′-N-芳基-氨甲基苯并-18-冠醚-6及聚苯乙烯珠体和硅胶支载冠醚的合成。后二者均可用作相转移催化剂。聚苯乙烯珠体支载的苯并-18-冠醚-6催化溴辛烷与氰化钾、氰化钠、或醋酸钾的取代反应时,活性较上述高聚物支载的苯并-15-冠醚-5为高。     

Molecular recognition by macropolycyclic hosts

The formation of complexes between crown ethers and aklylammonium cations may, to some extent, be modelled using standard molecular mechanics methods and an appropriate charge distribution scheme. Monocyclic crown ethers may be developed to give chromoionophores suitable for use in optical fibre based ion sensors. The incorporation of two crown ether systems into polycyclic host molecules which show highly selective complexation of guest bis-alkylammonium cations is described. The scope of these ditopic receptors may be extended by using metalloporphyrins in place of one or both of the crown ether binding sites.     

Crown Ether Host-Guest Molecular Ferroelectrics

In recent years, molecular ferroelectrics have received great attention due to their low weight, mechanical flexibility, easy preparation and excellent ferroelectric properties. Among them, crown-ether-based molecular ferroelectrics, which are typically composed of the host crown ethers, the guest cations anchored in the crown ethers, and the counterions, are of great interest because of the host-guest structure. Such a structure allows the components to occur order-disorder transition easily, which is beneficial for inducing ferroelectric phase transition. Herein, we summarized the research progress of crown ether host-guest molecular ferroelectrics, focusing on their crystal structure, phase transition, ferroelectric-related properties. In view of the small spontaneous polarization and uniaxial nature, we outlook the chemical design strategies for obtaining high-performance crown-ether-based molecular ferroelectrics. This minireview will be of guiding significance for the future exploration of crown ether host-guest molecular ferroelectrics.     

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.     

Ultrafast dynamics of liquid poly(ethylene glycol)s and crown ethers studied by femtosecond Raman-induced Kerr effect spectroscopy

Ultrafast molecular dynamics of liquid poly(ethylene glycol)s, tetra(ethylene glycol), penta(ethylene glycol), and poly(ethylene glycol) with the molecular weight of 600, and crown ethers, 12-crown-4 and 15-crown-5, have been investigated by means of femtosecond optical heterodyne-detected Raman-induced Kerr effect spectroscopy. Picosecond Kerr transients of poly(ethylene glycol)s and crown ethers are characterized by a biexponential function with the time constants of about 2 and 20 ps. Both the faster and slower time constants do not vary much among the five oligo(ethylene oxide)s. Femtosecond dynamics is discussed based on the Kerr (depolarized Raman) spectra obtained by Fourier transform deconvolution analysis of the high time resolution Kerr transients. The broad low-frequency band (0-200 cm(-1)) in the Kerr spectrum is analyzed by two Brownian oscillators. The spectral shapes of linear poly(ethylene glycol) and cyclic crown ether are very different. Both the low- and high-frequency Brownian oscillators for crown ethers show lower frequency and broader spectral features than those for poly(ethylene glycol)s. The comparison of the low-frequency spectra of poly(ethylene glycol)s and crown ethers shows that the low-frequency spectrum of 15-crown-5 is closer to that of poly(ethylene glycol)s than that of 12-crown-4 is. The difference of the low-frequency spectra between poly(ethylene glycol) and crown ether is discussed with the concepts of molecular conformation and liquid density. The features of the observed intramolecular vibrational bands are also correlated with the molecular conformations.     

冠醚修饰的固体支撑双层类脂膜的形成及性能研究

用饱和了胆固醇和饰用冠醚的角鲨烷／氯仿溶液作成膜液，制备了冠醚修饰的固体支撑双层类脂分子膜。重点考察了成膜物种及技术对膜稳定性及电特生影响。其膜电势随接触水相中的变化呈现Ｎｅｒｎｓｔ响应，线性范围１０＾－４－１０＾－１ｍｏｌ／Ｌ。     

网状聚合物冠醚的合成与性能—Ⅰ.以双环氧丙基醚、乙二醇双环氧丙基醚及多缩乙二醇双环氧丙基醚为原料合成

本文报道了一类新型网状聚合物冠醚的合成方法及其性能。分别通过双环氧丙基醚、乙二醇双环氧丙基醚及多缩乙二醇双环氧丙基醚等五种双环氧单体的网化聚合,直接合成了八种网状聚合物冠醚。聚合反应中分别采用了两种催化体系:BF₃·OEt₂和(i-Bu)₃Al。测定了网状聚合物冠醚对金属阳离子的络合容量及其在亲核取代反应中的相转移催化活性。实验表明,这类网状聚合物冠醚合成简便、性能良好且便于重复使用。     

Allylation of phenoxides by crown ethers and their polymers

Allylation of sodium phenoxide in the presence of crown ethers produces a high ratio of O/O + C allylation when conducted in water, phenol, benzene, or diethyl ether. The striking increase in the product ratios is attributed to specific complexation of the crown ethers that facilitate the dissociation of the ion pair aggregate of the sodioderivative in benzene or diethyl ether. The crown ethers may act as a phase transfer catalyst when the reaction is run in water. Furthermore, the O/O + C ratios of the allylation strongly depend on the kind of crown ethers used. To examine their effect the allylation of sodium phenoxide was studied with various crown ethers, such as 18-crown-6, benzo-18-crown-6, benzo-15-crown-5, poly(vinylmonobenzo-15-crown-5), and poly(vinylmono-benzo-18-crown-6), as catalysts. It was found that among these crown ethers poly(vinylmono-benzo-15-crown-5) was the most effective catalyst.     

Synthesis of lipophilic crown ethers with pendant phosphonic acid or phosphonic acid monoethyl ester groups

Synthetic routes to fifteen lipophilic crown ether phosphonic acid monoethyl esters and nine lipophilic crown ether phosphonic acids are described. For both classes of crown ethers which have pendant, protonionizable groups, the crown ether ring sizes are systematically varied from 12-crown-4 and 24-crown-8.     

DFT Study for a Series of Less-Symmetrical Crown Ethers and Their Complexes with Alkali Metal Cations

A series of ring‐contracted (14‐crown‐5, 17‐crown‐6) and ring‐enlarged (16‐crown‐5, 17‐crown‐5, 19‐crown‐6, 20‐crown‐6) crown ethers and their complexes with alkali‐metal cations Na⁺ and K⁺ had been explored using density functional theory (DFT) at B3LYP/6‐31G* level in order to reveal the effects of the methylene‐chain length in a crown ether. The nucleophilicity of all crown ethers had been investigated by the Fukui functions. The quantum chemistry parameters, such as the energy gap (ΔE), the highest occupied molecular orbital energy (E_HOMO) and the lowest unoccupied molecular orbital energy (E_LUMO) for less‐symmetrical crown ethers and symmetrical frameworks (15‐crown‐5, 18‐crown‐6) had been calculated. In addition, the thermodynamic energies of complexation reactions had also been studied. The results of the DFT calculations show that the methylene‐chain length plays an important role in determining the structure characters of the crown ethers and also strongly influences the properties of the ethers. Some of the calculated results are in a good agreement with the experimental values.     

Adsorption of polymers with crown ether substituents on muscovite mica

Ultrahigh specific surface area muscovite with different ions at the surface (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Ca²⁺, Sr²⁺, Ba²⁺, Cu²⁺) was treated with aqueous solutions of low molecular weight crown ethers and polymers with crown ether substituents. The adsorption was assessed by UV analysis of the supernatant solution, and with TGA and IR spectroscopy of the mica solids. In contrast to other layered silicates, the low molecular weight crown ethers show no affinity to any of the muscovite surfaces. The polymers can adsorb, however, depending on the type of surface cation. The results indicate that at least some of the crown ether moieties are complexed to surface cations and that the diameter of the ions at the surface plays an important role in the adsorption process.