含联萘基元的刚性环状齐聚物手性孔穴的振动圆二色谱研究

纳米尺度刚性环状齐聚物因其具有独特的孔穴结构,在基础与应用研究中引起了人们的广泛关注.当具有功能基团的分子骨架形成环状结构时,这种功能分子孔穴在分子识别及主-客体化学等方面具有广阔的应用前景.含有手性基团的手性大环分子具有特定的手性孔穴,在手性拆分、手性识别等方面引起了各国研究者的兴趣.     

含联萘基团的手性聚芳醚酮类环状齐聚物修饰电极的制备及其对色氨酸/磷钨杂多酸超分子化合物的手性识别

用溶剂诱导的含联萘基团的手性聚芳醚酮类环状齐聚物（S-PENEKC）制备修饰电极,利用循环伏安法实现了对D,L,DL-色氨酸／磷钨杂多酸的超分子化合物（D,L,DL—H,Trp2-[PW12O40]）的手性识别．     

可控交联聚醚醚酮的合成与热性能研究

聚醚醚酮因其优异的综合性能 (耐热性、耐水解、耐辐射等 )在许多领域得到应用 [1～ 4 ] .但聚醚醚酮的玻璃化转变温度 ( Tg)较低 ( 4 2 6K) ,导致其使用温度较低 (在 5 1 3K以下 ) .为进一步提高聚芳醚酮类材料的使用温度 ,人们在聚醚醚酮主链中引入刚性结构 ,通过提高聚芳醚酮的刚性度来提高聚芳醚酮的熔点 ( Tm)及 Tg,从而提高材料的使用温度 [5,6 ] .文献 [7]中聚芳醚酮的 Tm 已经高达 741 K,但此材料很难加工成型 .通常热塑性材料具有优异的加工性能 ,但使用温度较低 .热固性材料的使用温度较高 ,但在加工固定尺寸形状铸件时存在困…     

苯乙炔封端的可交联含氟聚芳醚的合成及性能

从光电集成器件对于材料性能的需要出发 ,我们相继合成了一系列可溶性的含氟聚芳醚和聚芳醚酮[1～ 5] .为了满足器件的多层化制备过程以及使器件成型后具有优异的性能 ,本文在间三氟甲基苯取代的聚芳醚 (1 1 F- PAE)中引进可交联的苯乙炔端基 ,合成了可热交联的高含氟量聚芳醚 ,并对其性能进行了初步研究 .1　实验部分1 .1　试剂与仪器　 4-苯乙炔苯酚 (PEP)按文献 [6 ]方法制备 ;3 -氟甲基苯代对苯二酚 (3 F- PH)按文献[2 ]方法制备 ;十氟联苯 ,Aldrich公司 ,99%;无水碳酸钾 ,A.R.级 ,天津化学试剂厂 ;甲苯 ,A.R.级 ,北京化工厂 ;N-…     

一类含联二萘结构的新型聚芳醚酮类刚性大环及其二聚体的合成与表征

通过一定的分子设计,利用一种全新的双酚单体(4-氯代苯基对苯二酚)和含有联二萘结构的双氟三聚体(BNDIF)经一步法合成环状齐聚物,制得了一类含有氯代苯基侧基和联二萘结构的新型聚芳醚酮类刚性大环;并通过氯苯基的催化偶联反应得到了该类刚性大环的二聚体(一类含有2个联二萘结构的新型结构双环齐聚物).利用MALDI-TOFMS和1HNMR及H-HCOSY分析,证明了目标产物的结构.     

芳香环状聚膦酸酯齐聚物的基质辅助激光解吸电离飞行时间质谱分析

用基质辅助激光解吸电离飞行时间质谱方法对一系列芳香环状聚膦酸酯低聚物进行了结构分析。比较了不同基质及阳离子剂对芳香环状聚膦酸酯分析结果的影响。1,8,9-蒽三酚基质仅对含有羰基基团聚膦酸酯环状齐聚物分析有效,而视黄酸基质则对所有聚膦酸酯环状剂聚物有效,是这类新型芳香环状齐聚物的适宜基质。环状聚膦酸酯齐聚物的阳离子齐分析表明,氯化锂是这种环状齐聚物的适宜的阳离子添加剂。     

酚酞聚芳醚酮酮环状齐聚物的合成及开环聚合

从4,4’-二氟三苯二酮(DFTBDK)和酚酞出发,利用"拟高稀(pseudo high dillution)"技术,一步法制备酚酞聚芳醚酮酮环状齐聚物(c-PEKK-C),成环率78%。基质辅助激光解吸电离飞行时间质谱MALDI-TOF MS数据表明,聚合产物系聚合度为n=2~8的环状低聚物,其中以二、三聚体为主要成分(占环化产物的85%)。运用J-S高分子环化理论证实4,4’-二氟三苯二酮的单体结构有利于形成环状化合物。以4,4’-联苯二酚钾盐为催化剂,在300~350℃范围内,N2气保护下,环状齐聚物进行熔融开环聚合反应得到相应的线性高相对分子质量酚酞聚芳醚酮酮(ROP-PEKK-C),GPC测得其Mw为1.2×105。     

可交联聚醚醚酮酮交替共聚物的合成与热交联研究

聚芳醚酮类特种工程塑料以其优异的机械性能、热稳定性、耐溶剂、耐辐照等特性在运输、航空航天、军事、电子、信息、核能等领域得到了广泛应用_{[1].聚醚醚酮的玻璃化转变温度(Tg)和熔点(Tm)分别为416和607 K,其长期使用温度为513 K,而其热分解温度在800 K以上,是热稳定性较好的聚合物之一.为了满足一些特殊需求,人们通过在聚芳醚酮的主链中引入刚性结构链,提高其主链的刚性程度,从而提高其T g和Tm,进而提高其使用温度[2～4].文献[5]报道的新型聚芳醚酮的T g和T m最高可达482和742 K,采用常规方法进行加工难度较大.为了在不提高加工温度的前提下提高聚芳醚酮类材料的使用温度,我们已成功地在聚醚醚酮的主链中引入可交联的硫醚结构,得到使用温度更高的可控交联聚醚醚酮材料,其可利用热塑性材料的加工方法进行加工,加工温度与聚醚醚酮相同,交联后的材料具有热固性材料的使用特性[6,7].为了拓宽可交联聚芳醚酮材料的种类,本文合成了一种类新型的可交联型聚醚醚酮酮材料,并对其热交联性能进行了研究.}     

含氮杂环聚芳醚酮三元共聚物的性能

聚芳醚酮是一种新型热塑性耐高温高分子材料,具有优异的力学性能、电性能、抗辐射性能等,特别适合作高性能复合材料的基质及超级工程塑料,关于聚芳醚酮已有多篇文章报道,而基于C-N偶合反应合成的聚芳醚酮报道甚少^[1],我们曾报道含氮杂环聚醚酮酮PPEKK的合成^[2].本文以1,4-二(4-氯代苯甲酰基)苯,4,4′-二氟二苯酮及4-(4-羟基苯基)-2,3-二氮杂 萘-1-酮为原料,合成了主链中含有C—N键的新型含氮杂环聚芳醚酮三元共聚物 (PPEKEKK),对共聚物的结构和性能进行了表征.     

侧基磺酸型含氟聚芳醚的合成

考察了多种高含氟量聚芳醚的磺化反应, 发现苯侧基的聚芳醚具有磺化反应条件简单, 磺化点与磺化度可控, 同时, 对其与质子交换膜材料相关的基本性能进行了表征.     

Expression of molecular chirality and two-dimensional supramolecular self-assembly of chiral, racemic, and achiral monodendrons at the liquid-solid interface

We have investigated the two-dimensional ordering of chiral and achiral monodendrons at the liquid-solid interface. The chiral molecules self-assemble into extended arrays of dimers. As expected, the R enantiomer forms the mirror image type pattern of the chiral two-dimensional structure formed by the S enantiomer. A racemic mixture applied from solution onto the substrate undergoes spontaneous segregation: the enantiomers separate on the surface and appear in different domains. In contrast to the chiral molecules, the achiral analogue self-assembles into cyclic tetramers. Moreover, the pattern formed by the achiral molecule strongly depends on the solvent used. In the case of 1-phenyloctane, solvent molecules are coadsorbed in a 2:1 (dendron:solvent) ratio whereas in 1-octanol, no solvent molecules are coadsorbed. By the appropriate solvent choice, the distance between the potential "supramolecular containers" can be influenced.     

Characteristic monomials with chirality fittingness for combinatorial enumeration of isomers with chiral and achiral ligands

A new method of combinatorial enumeration based on characteristic monomials with chirality fittingness (CM-CFs) has been proposed in order to enumerate isomers with chiral ligands as well as with achiral ones. The CM-CFs have been defined as monomials that consist of three kinds of dummy variables in light of the subduction of the Q-conjugacy representations for chiral and achiral cyclic groups. A procedure of calculating CM-CFs for cyclic groups and finite groups has been discribed so as to tabulate them as CM-CF tables. Then the CM-CF method has been applied to the enumeration of isomers with achiral ligands as well as chiral ones.     

Novel chiral liquid crystals based on amides and azo compounds derived from 2-amino-1,3,4-thiadiazoles: synthesis and mesomorphic properties

Novel chiral amides (Ia-Ie, II) and azo compounds (III, IV) with a 1,3,4-thiadiazole unit in the rigid core were synthesized and their liquid crystalline properties investigated by polarizing optical microscopy and differential scanning calorimetry. The amides Ia-Ie contain a chiral alkoxy chain derived from (R)-2-octanol and an achiral chain varying from 6 to 10 carbon atoms at the end of the rigid core. In amide II one of the terminal group is a chiral alkoxy chain derived from (S)-isoleucine and the other terminal substituent is an achiral n-decyloxy chain. Azo compounds III and IV contain an achiral n-decyloxy chain and a chiral alkoxy chain derived from (R)-2-octanol and (S)-isoleucine, respectively, at the end of the rigid core. The first homologue in the series of amides (Ia) exhibits enantiotropic smectic X (SmX)-chiral nematic (N*) dimorphism and the homologues Ib-Ie display enantiotropic SmX-chiral smectic C (SmC*)-N* mesomorphism. Amide II displays an enantiotropic smectic A phase. The azo compounds III and IV do not show smectic order and only an enantiotropic N* phase was observed. Thus, the mesomorphic behaviour depends on the nature of the central linkage and on the nature of the chiral alkoxy chain.     

On‐Surface Evolution of meso‐Isomerism in Two‐Dimensional Supramolecular Assemblies

Chiral structures created through the adsorption of molecules onto achiral surfaces play pivotal roles in many fields of science and engineering. Here, we present a systematic study of a novel chiral phenomenon on a surface in terms of organizational chirality, that is, meso‐isomerism, through coverage‐driven hierarchical polymorphic transitions of supramolecular assemblies of highly symmetric π‐conjugated molecules. Four coverage‐dependent phases of dehydrobenzo[12]annulene were uniformly fabricated on Ag(111), exhibiting unique chiral characteristics from the single‐molecule level to two‐dimensional supramolecular assemblies. All coverage‐driven phase transitions stem from adsorption‐induced pseudo‐diastereomerism, and our observation of a lemniscate‐type (∞) supramolecular configuration clearly reveals a drastic chiral phase transition from an enantiomeric chiral domain to a meso‐isomeric achiral domain. These findings provide new insights into controlling two‐dimensional chiral architectures on surfaces.     

Charge assisted chiral hybrid H-bonded molecular networks

The co-crystallisation of [Fe(CN)5NO]2- and cyclic achiral 1(2+) and chiral 2(2+) or 3(2+) bisamidinium tectons leads in the crystalline phase to the formation of 1-D H-bonded achiral and chiral molecular networks respectively. In all cases, the network is formed by mutual bridging of the anionic and cationic units through a chelate mode of H-bonding.     

Synthesis of stable and soluble one-handed helical homopoly(substituted acetylene)s without the coexistence of any other chiral moieties via two-step polymer reactions in membrane state: molecular design of the starting monomer

A soluble and stable one-handed helical poly(substituted phenylacetylene) without the coexistence of any other chiral moieties was successfully synthesized by asymmetric-induced polymerization of a chiral monomer followed by two-step polymer reactions in membrane state: (1) removing the chiral groups (desubstitution); and (2) introduction of achiral long alkyl groups at the same position as the desubstitution to enhance the solubility of the resulting one-handed helical polymer (resubstitution). The starting chiral monomer should have four characteristic substituents: (i) a chiral group bonded to an easily hydrolyzed spacer group; (ii) two hydroxyl groups; (iii) a long rigid hydrophobic spacer between the chiral group and the polymerizing group; (iv) a long achiral group near the chiral group. As spacer group a carbonate ester was selected. The two hydroxyl groups formed intramolecular hydrogen bonds stabilizing a one-handed helical structure in solution before and after the two-step polymer reactions in membrane state. The rigid long hydrophobic spacer, a phenylethynylphenyl group, enhanced the solubility of the starting polymer, and realized effective chiral induction from the chiral side groups to the main chain in the asymmetric-induced polymerization. The long alkyl group near the chiral group avoided shrinkage of the membrane and kept the reactivity of resubstitution in membrane state after removing the chiral groups. The g value (g = ([θ]/3,300)/ε) for the CD signal assigned to the main chain in the obtained final polymer was almost the same as that of the starting polymer in spite of the absence of any other chiral moieties. Moreover, since the one-handed helical structure was maintained by the intramolecular hydrogen bonds in a solution, direct observation of the one-handed helicity of the final homopolymer has been realized in CD for the solution for the first time.     

Chiral pair monolayer adsorption of iodine-substituted octadecanol molecules on graphite

High-resolution scanning tunneling microscopy has been used to examine the adsorbate structures formed when a racemic mixture of (9R,10R)-9,10-diiodooctadecan-1-ol and (9S,10S)-9,10-diiodooctadecan-1-ol is adsorbed at the basal plane of highly ordered pyrolytic graphite. The herringbone structure characteristic of the adsorption of long-chain molecules on graphite is observed. Close examination of the micrographs indicates a unique structure in which the chiral molecules adsorb in pairs, with one enantiomer filling half of the unit cell, and the other enantiomer filling the other half. Instead of forming separate chiral domains, as is sometimes observed when a racemic mixture adsorbs on an achiral surface, chiral pairs are formed and the pairs form an ordered monolayer, exposing opposite faces of the same molecule. An achiral racemic mixture is observed to form a chiral structure on an achiral surface in the regions of the surface examined here.     

Strictly diastereocontrolled photocyclodimerization of 2-anthracenecarboxylates tethered to cyclic tetrasaccharides

Photocyclodimerization of 2-anthracenecarboxylate tethered to a cyclic nigerosylnigerose scaffold gave a single chiral cyclodimer (out of two achiral and two chiral stereoisomers) in 99% optical and 96% chemical yields, achieving the ultimate stereocontrol of the supramolecular photochirogenesis in aqueous solution at 25 °C.     

Enantiospecific electrodeposition of chiral CuO films on single-crystal Cu(111)

Epitaxial films of monoclinic CuO have been electrodeposited on single-crystal Cu(111) from solutions containing either (S,S)- or (R,R)-tartrate. X-ray pole figure analysis reveals that the CuO film grown from (S,S)-tartrate exhibits a (1) out-of-plane orientation while the film grown from (R,R)-tartrate has a (11) orientation. Even though CuO does not crystallize within a chiral space group, the orientations obtained exhibit a surface chirality similar to that obtained from high index fcc metal surfaces. The films were shown to be enantioselective toward the catalytic oxidation of tartrate molecules by cyclic voltammetry. The technique should prove to be applicable to the electrodeposition of chiral surfaces of other low-symmetry materials on achiral substrates and should prove to be of use to those interested in the synthesis, separation, and detection of chiral molecules.     

Synthesis of chiral iridium complexes immobilized on amphiphilic polymers and their application to asymmetric catalysis

This article details the enantioselective catalytic performance of crosslinked, polymer immobilized, Ir‐based, chiral complexes for transfer hydrogenation of cyclic imines to chiral amines. Polymerization of the achiral vinyl monomer, divinylbenzene, and a polymerizable chiral 1,2‐diamine monosulfonamide ligand followed by complexation with [IrCl₂Cp*]₂ affords the crosslinked polymeric chiral complex, which can be successfully applied to asymmetric transfer hydrogenation of cyclic imines. Polymeric catalysts prepared from amphiphilic achiral monomers have high catalytic activity in the reaction and can be used both in organic solvents and water to give chiral cyclic amines with a high level of enantioselectivity (up to 98% ee). The asymmetric reaction allows for reuse of the heterogeneous catalyst without any loss in activity or enantioselectivity over several runs. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3037–3044