侧链液晶聚乙炔的合成及性能表征

取向液晶侧链引入聚乙炔主链促使主链共轭性提高,导致获得电活性和取向性的永久结合。最近,已有不少研究组将聚炔共轭聚合物作为刚性主链应用于制备侧链液晶聚合物。文中主要阐述带有液晶侧链聚乙炔的合成、液晶性及光学性能,并根据侧链液晶基元结构对其进行分类。     

酸酐固化侧链取代液晶环氧树脂的性能研究

采用DSC、DMA、TGA、SEM等研究了侧链取代液晶环氧树脂酸酐固化产物的动态力学和机械性能，并就侧链长度对液晶环氧树脂的性能影响进行了探讨。结果表明：侧链取代液晶环氧树脂表现出较高的模量和优良的耐热性能，其韧性也得到明显的改善。随着侧链长度的增加，固化产物的交联密度有所下降，随之下降的还有玻璃化转变温度、动态储能模量、弹性模量以及断裂伸长率。柔性链的增加也使其耐热性能下降，而其耐水性能则有所提高。     

取代聚乙炔的新应用

具有取代基的聚乙炔称取代聚乙炔。它通常是采用迁移金属催化剂使取代乙炔聚合而制得的,其主链上具有碳碳双键结构(见a式)。 RC≡CR’迁移金属催化剂→(C=C)n 取代聚乙炔引人注目的性能是具有高的气体透过性,最近对它在抗蚀剂材料、非线性光学材料、高分子磁性体等方面的应用开展了有关的基础研究。     

侧链液晶聚乙炔的最新研究进展

综述了侧链液晶聚乙炔的最新研究进展。根据侧链液晶基元结构的不同,介绍了这些聚合物材料的种类、结构和性质以及结构与性能的关系,着重介绍了结构对液晶性和发光性的影响。     

一种新型共轭接枝聚合物的合成及性能

将微波辐射合成的苯代三聚氰胺(BGA)-均苯四酸二酐(PMDA)体系的PAA与TDI-对位取代苯胺衍生物反应,通过改变TDI-对位取代苯胺衍生物的对位取代基来合成具有不同电子效应的侧链端基的接枝聚合物.用红外及核磁共振的测试方法对聚合物的结构进行表征.接枝聚合物具有较强的三阶非线性光学响应和较强的荧光性能.考察了侧链端基电子效应对聚合物三阶光学非线性极化率系数和荧光行为的影响.     

荧光共轭聚合物的合成及荧光淬灭研究

通过Sonogashira偶合反应合成了3种含pentiptycene基团、侧链分别含对称烷氧基取代、含非对称烷氧基取代和含烷基取代的聚对苯撑乙炔衍生物PPE-A、B和C.采用1H NMR,FT-IR,UV-Vis和PL等仪器对其进行了表征.讨论了侧链取代基类型对PPE溶解性和光学性能的影响;研究了间二硝基苯(m-DNB)和对硝基甲苯(p-NT)两种硝基化合物对PPE-A和B溶液的荧光淬灭影响,结果表明,PPE-A和B具有很高的荧光强度,对m-DNB和p-NT显示出良好的荧光响应.     

手性导电高分子聚合物的研究进展

手性导电高分子聚合物在手性高分子领域里有很多独特的化学性质,已成为功能材料领域的研究热点。综述了聚苯胺、聚吡咯和聚噻吩等一些经典手性导电高分子聚合物的合成途径:当共轭的导电聚合物链上带有对映体纯取代基或有手性的掺杂阴离子时,其光学活性可以被π-π*电子吸收带所诱导;阐述了它们的合成发展史、现状、显著特性及手性导电高聚合物的应用前景。     

上海有机所在多环天然产物全合成研究中取得进展

正甾体类天然产物在生物体内常常充当信号分子,因此具有重要的生理活性。该家族中的一小部分成员具有破缺的骨架结构,被称为开环甾体,其化学合成和生物活性研究尚未引起充分关注。2015年,筑波大学的Kigoshi研究组报道了从海兔Aplysia kurodai中分离的开环甾醇aplysiasecosterol A。该化合物的自然含量非常稀少,但具有特别的化学结构:三环双酮母核通过碳-碳单键连接高度取代的环戊烷侧链,分子中连续8个手性中心对化学合成提出了一定挑战。     

含偶氮侧基聚酰胺酸的合成及三阶非线性光学性质

选取苯代三聚氰胺(BGA)和均苯四酸二酐(PMDA)为单体进行微波辐射溶液聚合反应,所得的聚酰胺酸(PAA)与对位取代基不同的苯胺重氮盐偶合接枝．从而合成了一系列新的具有三阶非线性光学活性的侧链型聚合物。通过红外、紫外、元素分析、拉曼、核磁等测试方法对接枝聚合物的结构进行了表征。通过简并四波混频飞秒激光系统对各个接枝聚合物的三阶非线性极化率系数进行了测定．考察了偶氮侧链的引入对聚合物主链三阶非线性的影响,并考察了侧链上不同取代基的电子效应对主链三阶非线性的影响。结果表明．侧链上偶氮基对提高聚合物主链三阶非线性具有一定的贡献,取代基的电子效应也对聚合物的三阶非线性具有不同的影响。     

一种长侧链取代液晶环氧单体的酸酐固化与性能

采用非等温差示扫描量热法(DSC)研究了一种长侧链取代液晶环氧单体与甲基六氢苯酐的固化反应历程,考察了体系的固化反应动力学特征.并通过POM、WAXD、SEM、TGA和DMA 等对其等温固化产物的相结构、热性能和动态力学性能等进行表征和分析.结果表明,侧链的存在使其固化反应具有良好的可控性.固化反应活化能为77.8 kJ/mol,固化反应后期为扩散控制.液晶环氧单体经固化后呈向列相,其力学和耐热性能优良,韧性也得到明显改善.     

Supramolecular Chiroptical Switches Based on Achiral Molecules

Chirality plays an important role in biological and material sciences. By introducing chiral elements into functional materials, new properties are created and an increase in information density can be achieved. Chiral properties of functional materials do not only rely on molecular structure, but also on supramolecular interaction between the building blocks. In contrast to the generally accepted opinion that chiral systems should include chiral molecules, this Research News introduces the role of achiral molecules in realizing chiral properties in films and gel‐like materials. Even a system that is entirely composed of achiral molecules can exhibit interesting chiroptical properties in supramolecular ultrathin films. This article demonstrates how achiral molecules can be assembled into supramolecular chiral films and organogels. It further shows how the incorporated achiral molecules can be used to switch the chiral properties of these supramolecular films and organogels.     

Chiral Assemblies of Laser-Printed Micropillars Directed by Asymmetrical Capillary Force

Artificial microstructures composed of chiral building blocks are of great significance in the fields of optics and mechanics. Here, it is shown that highly ordered chiral structures can be spontaneously assembled by a meniscus-directed capillary force arising in an evaporating liquid. The chirality is facilitated by rationally breaking the intrinsic symmetry in the unit cells through cooperative control of the geometry and spatial topology of the micropillars. The interfacial dynamics of the assembly process are studied to show that the sequential self-organization of the micropillars is influenced by the geometries, stiffness, and spatial arrangements. A diversity of chiral assemblies with controlled handedness is yielded by varying the pillar number, height, cross-section, laser power, and spatial topology. Lastly, the differential reflectance of light carrying opposite orbital angular momentums on the assembled chiral architectures are investigated, showcasing their potential in the field of chiral photonics concerning enantioselective response and exceptional optical functions.     

Polycarboxylate derivative of <Emphasis Type="Italic">α</Emphasis>-amino acid as growth modifier of sulphide minerals

Construction of modified inorganic mineral with controlled mineralization analogues of those produced by nature is now of current interest for understanding the mechanism of the in vivo biomineralization processes, as well as looking for fresh industrial and technological applications. Low-molecular-weight chiral polycarboxylate ligands derived from naturally occurring L-α-amino acids have been used as model systems to study the effect of small organic matrix on crystal growth modification. The sulphide minerals are characterized by PXRD, FT–IR and SEM. Furthermore, the optical properties of these minerals have been characterized by UV-Vis and photoluminescence (PL) spectra.     

Playing with carbon and silicon at the nanoscale

Because of its superior properties silicon carbide is one of the most promising materials for power electronics, hard- and biomaterials. In the solid phase, the electronic and optical properties are controlled by the stacking of double layers of Si and C atoms. In thin films, a change in the stacking order often requires stress, which can be achieved naturally in systems with nanometre length scale. For this reason, nanotubes, nanowires and clusters can be used as building blocks for the synthesis of novel materials. Furthermore, playing at the nanometre length scale enables the nature of the SiC bonding to be modified, which is of prime importance for atomic engineering of nanostructures. In this review, emphasis is placed on the theoretical principles associated with SiC cage-like clusters and experimental work resulting from them.     

激光防护光学材料的设计及性能研究

随着激光设备的不断发展，自动化程度的不断提高，它对人眼及各种电子装置的干扰、损伤等的威胁也越来越大，激光防护越来越受到各国的重视。报道了激光防护共轭功能高分子的分子设计，合成系列共轭高分子，采用FT-IR、^1H NMR、UV、GPC和TGA对分子结构和热性能进行表征，测试了高分子的光限幅和非线性光学性能，讨论了高分子材料热性能增强与光限幅产生的机理以及分子结构与高分子光学性能之间的关系。     

Supramolecular Helices: Chirality Transfer from Conjugated Molecules to Structures

Different scales of chirality endow a material with many excellent properties and potential applications. In this review, using π‐conjugated molecules as functional building blocks, recent progress on supramolecular helices inspired by biological helicity is summarized. First, induced chirality on conjugated polymers and small molecules is introduced. Molecular chirality can be amplified to nanostructures, superstructures, and even macroscopic structures by a self‐assembly process. Then, the principles for tuning the helicity of supramolecular chirality, as well as formation of helical heterojunctions, are summarized. Finally, the potential applications of chiral structures in chiral sensing and organic electronic devices are critically reviewed. Due to recent progress in chiral structures, an interdisciplinary area called “chiral electronics” is expected to gain wide popularity in the near future.     

导电高分子聚噻吩衍生物的研究进展

聚噻吩是研究最为广泛的功能高分子材料。介绍了烷基取代、带支链和杂原子取代的各类聚噻吩衍生物的结构和合成方法 ,以及其作为新型的导电高分子材料的电光学性能和应用研究     

Chiromagnetic Plasmonic Nanoassemblies with Magnetic Field Modulated Chiral Activity

Chiral plasmonic nanoassemblies, which exhibit outstanding chiroptical activity in the visible or near‐infrared region, are popular candidates in molecular sensing, polarized nanophotonics, and biomedical applications. Their optical chirality can be modulated by manipulating chemical molecule stimuli or replacing the building blocks. However, instead of irreversible chemical or material changes, real‐time control of optical activity is desired for reversible and noninvasive physical regulating methods, which is a challenging research field. Here, the directionally and reversibly switching optical chirality of magneto‐plasmonic nanoassemblies is demonstrated by the application of an external magnetic field. The gold‐magnetic nanoparticles core–satellite (Au@Fe₃O₄) nanostructures exhibit chiral activity in the UV–visible range, and the circular dichroism signal is 12 times greater under the magnetic field. Significantly, the chiral signal can be reversed by regulating the direction of the applied magnetic field. The attained magnetic field‐regulated chirality is attributed to the large contributions of the magnetic dipole moments to polarization rotation. This magnetic field‐modulated optical activity may be pivotal for photonic devices, information communication, as well as chiral metamaterials.     

Circular Dichroism Studies on Plasmonic Nanostructures

In recent years, optical chirality of plasmonic nanostructures has aroused great interest because of innovative fundamental understanding as well as promising potential applications in optics, catalysis and sensing. Herein, state‐of‐the‐art studies on circular dichroism (CD) characteristics of plasmonic nanostructures are summarized. The hybrid of achiral plasmonic nanoparticles (NPs) and chiral molecules is explored to generate a new CD response at the plasmon resonance as well as the enhanced CD intensity of chiral molecules in the UV region, owing to the Coulomb static and dynamic dipole interactions between plasmonic NPs and chiral molecules. As for chiral assembly of plasmonic NPs, plasmon–plasmon interactions between the building blocks are found to induce generation of intense CD response at the plasmon resonance. Three‐dimensional periodical arrangement of plasmonic NPs into macroscale chiral metamaterials is further introduced from the perspective of negative refraction and photonic bandgap. A strong CD signal is also discerned in achiral planar plasmonic nanostructures under illumination of circular polarized plane wave at oblique incidence or input vortex beam at normal incidence. Finally perspectives, especially on future investigation of time‐resolved CD responses, are presented.     

Chiral melamine derivatives: design, synthesis, and application to mass spectrometry-based chiral analysis

A novel class of chiral melamine derivatives has been designed and synthesized. The ability of these compounds to perform chiral recognition toward 19 natural chiral alpha-amino acids has been investigated by electrospray ionization tandem mass spectrometry for the first time. The enantioselectivities of these new chiral selectors are encouraging. To elucidate some mechanism and regularity in the chiral recognition process using chiral melamine derivatives as chiral selectors, the effect of different noncovalent interactions caused by various chiral or achiral moieties in melamine derivatives on the chiral recognition in the gas phase has been studied at the same time. The result shows that electrostatic, hydrogen bond, pi-pi stacking, and steric interaction between selector and analyte play important roles in the association and enantioselective recognition of amino acids with the chiral melamine derivatives as chiral selectors. Enantiodiscrimination for analytes with different structures and properties could be improved by modifying substituents in melamine derivatives on purpose.