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排序方式: 共有247条查询结果,搜索用时 31 毫秒
91.
Yuan WZ Hu R Lam JW Xie N Jim CK Tang BZ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(10):2847-2856
Triphenylamine (TPA)-based conjugated hyperbranched poly(aryleneethynylene)s (PAEs), hb-P1/2, hb-P1/3, and hb-P1/4, were synthesized with high molecular weights and good solubilities through Sonogashira coupling reactions. These PAEs exhibited outstanding thermal stabilities and different emission behaviors. Tetraphenylethene (TPE)-containing hb-P1/2 fluoresced faintly in THF, although its light emission was enhanced by aggregate formation in aqueous media or in thin films, thereby exhibiting an aggregation-induced emission-enhancement (AIEE) effect. Whereas 1,1,2,3,4,5-hexaphenylsilole (HPS)-bearing hb-P1/3 showed no significant change in emission intensity with increasing water content in aqueous media, hb-P1/4, which consisted of TPA-fluorenone donor-acceptor groups, presented almost identical absorptions, but both positive and negative solvatochromic emissions in various solvents. A superquenching effect was observed in the picric-acid-detection process by using nanosuspensions of hb-P1/2. All of the polymers possessed good film formability. UV irradiation of the thin films induced simultaneous photobleaching and cross-linking, thus making them applicable in the fabrication of 2D and 3D patterns. Furthermore, the polymer films also showed high refractive indices, which were tunable upon exposure to UV light. 相似文献
92.
Variational formulations for classical dissipative equations, namely friction and diffusion equations, are given by means of fractional derivatives. In this way, the solutions of those equations are exactly the extremal of some fractional Lagrangian actions. The formalism used is a generalization of the fractional embedding developed by Cresson [Fractional embedding of differential operators and Lagrangian systems, J. Math. Phys. 48 (2007) 033504], where the functional space has been split in two in order to take into account the asymmetry between left and right fractional derivatives. Moreover, this asymmetric fractional embedding is compatible with the least action principle and respects the physical causality principle. 相似文献
93.
A new bis(aroylacetylene) containing tfiazole and fluorene moieties is synthesized by click chemistry. Polycyclotrimerization of the monomer is catalyzed by piperidine in refluxed dioxane,furnishing a regioregular poly(aroylarylene) in a satisfactory yield.The hyperbranched structure of the polymer is characterized spectroscopically with satisfactory results.The polymer enjoys no metal detriment and is soluble in common organic solvents such as tetrahydrofuran (THF),chloroform,dichloromethane (DCM),and N... 相似文献
94.
Jiajie Zeng Jingjing Guo Hao Liu Jacky W. Y. Lam Zujin Zhao Shuming Chen Ben Zhong Tang 《化学:亚洲杂志》2019,14(6):828-835
Aggregation‐induced delayed fluorescence (AIDF) can be regarded as a special case of aggregation‐induced emission (AIE). Luminogens with AIDF can simultaneously emit strongly in solid state and fully utilize the singlet and triplet excitons in organic light‐emitting diodes (OLEDs). In this work, two new AIDF luminogens, DMF‐BP‐DMAC and DPF‐BP‐DMAC, with an asymmetric D–A–D′ structure, are designed and synthesized. The characteristics of both luminogens are systematically investigated, including single crystal structures, theoretical calculations, photophysical properties and thermal stabilities. Inspired by their AIDF nature, the green‐emission non‐doped OLEDs based on them are fabricated, which afford good electroluminescence performances, with low turn‐on voltages of 2.8 V, high luminance of 52560 cd m?2, high efficiencies of up to 14.4 %, 42.3 cd A?1 and 30.2 lm W?1, and very small efficiency roll‐off. The results strongly indicate the bright future of non‐doped OLEDs on the basis of robust AIDF luminogens. 相似文献
95.
Chenchen Liu Jun-Cheng Yang Jacky W. Y. Lam Hai-Tao Feng Ben Zhong Tang 《Chemical science》2022,13(3):611
Chirality is important to chemistry, biology and optoelectronic materials. The study on chirality has lasted for more than 170 years since its discovery. Recently, chiral materials with aggregation-induced emission (AIE) have attracted increasing interest because of their fascinating photophysical properties. In this review, we discussed the recent development of chiral materials with AIE properties, including their molecular structures, self-assembly and functions. Generally, the most effective strategy to design a chiral AIE luminogen (AIEgen) is to attach a chiral scaffold to an AIE-active fluorophore through covalent bonds. Moreover, some propeller-like or shell-like AIEgens without chiral units exhibit latent chirality upon mirror image symmetry breaking. The chirality of achiral AIEgens can also be induced by some optically active molecules through non-covalent interactions. The introduction of an AIE unit into chiral materials can enhance the efficiency of their circularly polarized luminescence (CPL) in the solid state and the dissymmetric factors of their helical architectures formed through self-assembly. Thus, highly efficient circularly polarized organic light-emitting diodes (CPOLEDs) with AIE characteristics are developed and show great potential in 3D displays. Chiral AIEgens are also widely utilized as “turn on” sensors for rapid enantioselective determination of chiral reagents. It is anticipated that the present review can entice readers to realize the importance of chirality and attract much more chemists to contribute their efforts to chirality and AIE study.This review highlights the recent development of chiral materials with aggregation-induced emission properties, including their molecular structures, self-assembly and functions. 相似文献
96.
97.
Tunable Photochromism in the Robust Dithienylethene‐Containing Phospholes: Design,Synthesis, Characterization,Electrochemistry, Photophysics,and Photochromic Studies 下载免费PDF全文
Dr. Jacky Chi‐Hung Chan Dr. Hok‐Lai Wong Prof. Dr. Wing‐Tak Wong Prof. Dr. Vivian Wing‐Wah Yam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(18):6936-6948
A series of dithienylethene‐containing phosphole derivatives has been designed, synthesized and characterized. One of the compounds has been characterized by X‐ray crystallography. Upon photoexcitation, the compounds exhibit drastic color changes, ascribed to the reversible photochromic behavior. Their photochromic, photophysical and electrochemical properties have been studied. They show photochromic reactivities with high photocyclization quantum yields. Their photophysical and photochromic properties are found to be facilely tuned in this system by substitution at the phosphole backbone, as well as variation on the extent of π‐conjugation of the phosphole backbone. Some selected compounds have been demonstrated to exhibit photochromic properties in polymethylmethacrylate (PMMA) films. 相似文献
98.
Jacky Cresson 《Journal of Differential Equations》2004,196(2):289-300
Let A be a (normally) hyperbolic compact invariant manifold of an analytic diffeomorphism f of an analytic manifold M. We assume that the stable and unstable manifold of A intersect transversally (in an admissible way), the dynamics on A is ergodic and the modulus of the eigenvalues associated to the stable and unstable manifold, respectively, satisfy a non-resonance condition. In the case where A is a point or a torus, we prove that the discrete dynamical system associated to f does not admit an analytic first integral. The proof is based on a triviality lemma, which is of combinatorial nature, and a geometrical lemma. The same techniques, allow us to prove analytic non-integrability of Hamiltonian systems having Arnold diffusion. In particular, using results of Xia, we prove analytic non-integrability of the elliptic restricted three-body problem, as well as the planar three-body problem. 相似文献
99.
Jacky Cresson 《Journal of Differential Equations》2003,187(2):269-292
We consider hyperbolic tori of three degrees of freedom initially hyperbolic Hamiltonian systems. We prove that if the stable and unstable manifold of a hyperbolic torus intersect transversaly, then there exists a hyperbolic invariant set near a homoclinic orbit on which the dynamics is conjugated to a Bernoulli shift. The proof is based on a new geometrico-dynamical feature of partially hyperbolic systems, the transversality-torsion phenomenon, which produces complete hyperbolicity from partial hyperbolicity. We deduce the existence of infinitely many hyperbolic periodic orbits near the given torus. The relevance of these results for the instability of near-integrable Hamiltonian systems is then discussed. For a given transition chain, we construct chain of hyperbolic periodic orbits. Then we easily prove the existence of periodic orbits of arbitrarily high period close to such chain using standard results on hyperbolic sets. 相似文献
100.
Qiyao Li Junyi Gong Ying Li Ruoyao Zhang Haoran Wang Jianquan Zhang He Yan Jacky W. Y. Lam Herman H. Y. Sung Ian D. Williams Ryan T. K. Kwok Min-Hui Li Jianguo Wang Ben Zhong Tang 《Chemical science》2021,12(2):709
Developing versatile synthetic methodologies with merits of simplicity, efficiency, and environment friendliness for five-membered heterocycles is of incredible importance to pharmaceutical and material science, as well as a huge challenge to synthetic chemistry. Herein, an unexpected regioselective photoreaction to construct a fused five-membered azaheterocycle with an aggregation-induced emission (AIE) characteristic is developed under mild conditions. The formation of the five-membered ring is both thermodynamically and kinetically favored, as justified by theoretical calculation and experimental evidence. Markedly, a light-driven amplification strategy is proposed and applied in selective mitochondria-targeted cancer cell recognition and fluorescent photopattern fabrication with improved resolution. The work not only delivers the first report on efficiently generating a fused five-membered azaheterocyclic AIE luminogen under mild conditions via photoreaction, but also offers deep insight into the essence of the photosynthesis of fused five-membered azaheterocyclic compounds.A multifunctional, AIE-based, fused five-membered azaheterocycle is photogenerated with light-driven amplification to combat the photobleaching issue and fabricate display materials. 相似文献