共查询到20条相似文献,搜索用时 93 毫秒
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手性分子光学开关在光学储存、 光学通信以及三维立体显示等领域有着重要的应用价值. 但是目前的手性分子光学开关存在材料种类少、 光学可调性差、 稳定性差等缺点, 如何构筑出具有高光学可调性以及稳定性的手性光学切换体系依旧是一项严峻的挑战. 本工作基于电致酸/碱理论, 通过将手性联萘官能团引入到酸响应的罗丹明主体结构中, 设计并合成了一种新型的酸响应手性光学开关分子, 并将其与电致酸材料相结合, 成功实现了电场驱动的手性光学开关过程, 开发了一种新型的手性光学切换体系. 发现在合适的电场控制下, 其颜色、 荧光以及圆二色谱信号均能发生可逆的变化. 这种方法为构筑新型手性光学开关体系提供了一种新思路, 对手性光学开关材料的应用拓展具有重要的参考价值. 相似文献
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光响应胆甾相液晶是一类在光刺激下通过改变液晶分子排列调控光学特性的智能“软”光子晶体材料,其分子自组装形成周期性螺旋结构,选择性地反射与自身螺旋方向相同的圆偏振光。近年来,利用光刺激诱导胆甾相液晶在左手螺旋和右手螺旋之间发生螺旋翻转的研究引起了广泛关注。胆甾相液晶的螺旋翻转能够改变反射光的圆偏振特性,有望拓展光子晶体材料在可调节滤光器、防伪与加密技术、圆偏振激光器、三维显示等领域的潜在应用。本综述重点关注光响应胆甾相液晶螺旋翻转的研究进展;总结了调控胆甾相液晶螺旋方向的两种主要策略:(1)直接引入螺旋性可逆转变的光响应手性分子开关,(2)利用光响应手性分子开关和与之螺旋性相反的手性掺杂剂之间的手性竞争;分析了分子空间构型转变对调控螺旋翻转程度的影响;并讨论了不同材料体系面临的挑战以及未来的发展方向。 相似文献
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超分子凝胶中的光化学反应是比较特殊的一类反应,通常是将具有光响应活性的基团或分子引入到超分子凝胶的自组装体系中,因此,能够将超分子凝胶独特的性质与光化学反应的优势有效地结合起来,构筑新型的光功能材料,这使得此类超分子凝胶在光信息存储、光开关及光转换器件等前沿领域具有广阔的应用前景.本文主要总结近年来国内外包括作者课题组对超分子凝胶中光化学反应方面的研究进展,以及其在多重响应凝胶、手性光学开关以及手性合成方面的应用. 相似文献
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有机分子笼是一类具有独特内在空腔的三维有机分子,在分子识别与分离、催化反应、气体吸附与存储等领域有着广阔的应用前景。有机分子笼的性能主要取决于骨架分子的化学结构与键合方式,而目前成功用于合成有机分子笼的前驱分子种类还比较有限,尤其是手性分子笼。近来,上海交通大学邱惠斌课题组以具有本征螺旋共轭结构的螺烯作为骨架分子,通过动态共价键等可逆键合过程,构建了一系列具有手性超级结构的有机分子笼,在手性识别与分离、圆偏振发光、手性分子开关等应用领域进行了积极探索。 相似文献
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This paper presents a review on kaurane diterpenes and their glycoside derivatives, covering aspects of their occurrence, biological activities and the synthesis of these natural products and their analogues. First, it shows and classifies diterpenes, in accordance with the already established structural criteria in the literature. Then, kaurane diterpenes are presented, focusing on their chemical structures, occurrence in the plant kingdom and their main, recently described, biological activities. Moreover, the most significant works, published between 1964 and November 2006, which describe the total synthesis or structural transformations of some kaurane diterpenes, including either semisynthetic and/or microbiological methodologies, are consisely reviewed. At this point, some general considerations on glycosides are introduced, and kaurane glycosides are presented and discussed on the basis of their toxic importance and occurrence in the plant kingdom, having focused on related aspects of their biological activities and the relationships between these activities and the structural factors of their molecules. Finally, the principal methods of glycosidation by enzymatic and chemical processes are both presented, and a few papers on the synthesis of kaurane glycosides are succinctly discussed. 相似文献
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R. M. Minas’yan 《Polymer Science Series D》2008,1(4):286-288
One-component adhesives-sealants, mechanisms of their synthesis and cure, the most important fields of their application, and peculiarities of their production under actual plant conditions are described. The assortment of domestic adhesives-sealants and their main developers and producers are reported. The most important parameters of the properties of domestic one-component adhesives-sealants, Elastosil, Pentelast, Avtogermesil, and other grades, are discussed. 相似文献
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Summary Two oxidation procedures for the synthesis of silicabased aliphatic sulfonic acid cation-exchangers for HPLC are described. Several reaction conditions for oxidizing a terminal-bonded thiol with organic peroxides are provided along with their yields, capacities, reproducibility, and chromatographic behavior. Also, three methods for determining exchange capacity are discussed, and their relationship to the capacity factors of charged solutes is compared. The maximum capacity determined by the titration of the bonded silica was 0.34 meq/gram. The general problems of synthesizing cation-exchangers, measuring their efficiencies and exchange capacities, and evaluating their overall performances are outlined. 相似文献
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Alan E. Tonelli 《Journal of Polymer Science.Polymer Physics》2009,47(16):1543-1553
Cyclodextrins (CDs) are cyclic starches containing α‐1,4‐linked glucose units. Commonly available α‐, β‐, and γ‐CDs have six, seven, and eight glucose units, respectively. They are well known for forming noncovalent inclusion complexes (ICs) with a variety of guest molecules, including many polymers, by threading and inclusion into their relatively hydrophobic interior cavities, which are roughly cylindrical, with diameters of ~0.5–1.0 nm. Warm water washing of crystalline CD‐ICs containing polymer guests insoluble in water or treatment with amylase enzymes serve to remove the host CDs and result in the coalescence of the guest polymers into solid bulk samples. When guest polymers are coalesced from their CD‐ICs by carefully removing the host CD lattices, they are observed to solidify with structures, morphologies, and even conformations that are distinct from bulk samples made from their solutions and melts. In addition, molecularly mixed, intimate blends can be obtained upon coalescence of two or more normally immiscible polymer guests from their common CD‐ICs. Not only are the organizations and behaviors of bulk polymer samples significantly modified on coalescence from their CD‐ICs, but both are also maintained for significant periods of time even when heated above their Tgs and Tms, where their chains are mobile. Here, we discuss the long‐time, high temperature stabilities of the organizations and properties of bulk polymers coalesced from their crystalline CD‐ICs. While random‐coiling of their initially coalesced, largely extended, separated, and unentangled chains may be relatively rapid, we conclude that the subsequent slow establishment of homogeneous melts or phase‐segregated blends results from the extremely sluggish center‐of‐mass diffusion that must accompany full entanglement of their chains. Apparently, the process of entangling the largely separated and not fully interpenetrating randomly coiled chains initially coalesced from their CD‐ICs is particularly slow, much slower in fact than the center‐of mass diffusion of polymer chains in their fully entangled melts. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1543–1553, 2009 相似文献
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Atomic clusters characterized by finite size, low dimensionality, and reduced coordination number exhibit many novel properties that are very different from their bulk. As these clusters are assembled, their properties can be significantly altered due to the interaction of these clusters with each other as well as with their support. This paper provides a brief review of the cluster properties that are affected when clusters are deposited on metallic or organic substrates, isolated in matrices or in zeolite cages, coated with acetate ligands, or simply allowed to self-assemble without the presence of any reactive species. It is shown that the interface between the clusters and their support can play an important role on the properties of clusters as their unique characteristics do. 相似文献
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Dr. Sudhina Guragain Dr. Bishnu Prasad Bastakoti Dr. Victor Malgras Prof. Kenichi Nakashima Prof. Yusuke Yamauchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(38):13164-13174
Stimuli‐responsive materials are of immense importance because of their ability to undergo alteration of their properties in response to their environment. The properties of such materials can be tuned by subtle adjustments in temperature, pH, light, and so forth. Among such smart materials, multi‐stimuli‐responsive polymeric materials are of pronounced significance as they offer a wide range of applications and their properties can be tuned through several mechanisms. Here, we aim to highlight some recent studies showcasing the multi‐stimuli‐responsive character of these polymers, which are still relatively little known compared to their single‐stimuli‐responsive counterpart. 相似文献
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Electron-deficient 1- and 2-azabuta-1,3-dienes are reagents intrinsically able to provide a wide range of cyclic and acyclic N-containing building blocks. Depending on their substitution, they behave as dienes for Diels-Alder reactions, as partners for [4+1], [3+2], [2+2]-cycloadditions, for aziridinations and as electrophiles for 1,2 and 1,4-additions. Nowadays, they are a very versatile family of compounds, despite their usual instability and complex reactivity. Four decades of research in this challenging area are reviewed in this critical review: their synthetic aspects and their reactivity towards a wide range of dienophiles, dipoles and nucleophiles are described as well. The introduction focuses on their electronic properties in order to get a clear picture of their reactivity (190 references). 相似文献
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Barbara J. Barker Joseph Rosenfarb Joseph A. Caruso 《Angewandte Chemie (International ed. in English)》1979,18(7):503-507
N-Alkylated ureas, including cyclic derivatives, are readily obtained pure. These stable compounds are already used as industrial solvents owing to their considerable solvent power, their wide liquid range, and their favorable dielectric constants and dipole moments. They are being increasingly employed as reaction media for electrochemical and analytical studies. 相似文献
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Pasqualina Liana Scognamiglio Chiara Platella Ettore Napolitano Domenica Musumeci Giovanni Nicola Roviello 《Molecules (Basel, Switzerland)》2021,26(12)
Peptides and their synthetic analogs are a class of molecules with enormous relevance as therapeutics for their ability to interact with biomacromolecules like nucleic acids and proteins, potentially interfering with biological pathways often involved in the onset and progression of pathologies of high social impact. Nucleobase-bearing peptides (nucleopeptides) and pseudopeptides (PNAs) offer further interesting possibilities related to their nucleobase-decorated nature for diagnostic and therapeutic applications, thanks to their reported ability to target complementary DNA and RNA strands. In addition, these chimeric compounds are endowed with intriguing self-assembling properties, which are at the heart of their investigation as self-replicating materials in prebiotic chemistry, as well as their application as constituents of innovative drug delivery systems and, more generally, as novel nanomaterials to be employed in biomedicine. Herein we describe the properties of nucleopeptides, PNAs and related supramolecular systems, and summarize some of the most relevant applications of these systems. 相似文献