- Green-, Red-, and Infrared-Emitting Polymorphs of Sterically Hindered Push–Pull Substituted Stilbenes
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The synthesis, XRD single-crystal structure, powder XRD, and solid-state fluorescence of two new DPA-DPS-EWG derivatives (DPA=diphenylamino, DPS=2,5-diphenyl-stilbene, EWG=electron-withdrawing group, that is, carbaldehyde or dicyanovinylene, DCV) are described. Absorption and fluorescence maxima in solvents of various polarity show bathochromic shifts with respect to the parent DPA-stilbene-EWGs. The electronic coupling in dimers and potential twist elasticity of monomers were studied by density functional theory. Both polymorphs of the CHO derivative emit green fluorescence (527 and 550 nm) of moderate intensity (10 % and 5 %) in polycrystalline powder form. Moderate (5 %) red (672 nm) monomer-like emission was also observed for the first polymorph of the DCV derivative, whereas more intense (32 %) infrared (733 nm) emission of the second polymorph was ascribed to the excimer fluorescence.
- Pauk, Karel,Luňák, Stanislav,R??i?ka, Ale?,Marková, Aneta,Mausová, Anna,Kratochvíl, Matou?,Melánová, Klára,Weiter, Martin,Imramovsky, Ale?,Vala, Martin
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- On-Surface Growth of Single-Layered Homochiral 2D Covalent Organic Frameworks by Steric Hindrance Strategy
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Investigation of chirality in on-surface synthesis is of significance not only for fabricating atomically precise covalently bonded chiral species but also for unveiling chiral phenomena involving chemical reactions. In this contribution, we present the growth of single-layered homochiral 2D covalent organic frameworks (COFs) on surfaces based on a steric hindrance strategy, by which both the chiral expression of the prochiral precursor and the newly formed Ca N bonds are successfully steered. When coupling a tritopic monomer with the prochiral ditopic molecule with phenyl substituents, two enantiomers of the precursor are randomly integrated in the product via variable Ca N linkages, resulting in distorted hexagonal frameworks without chiral expression. After equipping the prochiral precursor with more hindered bulky substituents, highly regular homochiral 2D COFs are fabricated, in which only one of the enantiomers of the prochiral precursor is integrated, and all Ca N linkages possess the same configuration. Structural analysis based on high resolution scanning tunneling microscopy images and theoretical simulations indicate that the homochiral 2D COFs are generated through an enantioselective on-surface polymerization driven by the steric hindrance effect. This result not only benefits understanding and controlling chirality in on-surface synthesis but also provides a new approach for the growth of highly regular COFs on surfaces.
- Chen, Ting,Hong, Ye,Lu, Cheng,Mo, Yi-Ping,Wan, Li-Jun,Wang, Dong,Yang, Zhi-Yong
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- Stimulated Emission-Controlled Photonic Transistor on a Single Organic Triblock Nanowire
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In this work, we demonstrate a stimulated emission-controlled photonic transistor on a single organic triblock nanowire composed of alternate energy donor and acceptor. The population of acceptor excitons was engineered by energy transfer to achieve enhanced fluorescence, which was further amplified by the stimulated emission of the donor and the optical feedback in the nanowire microcavities, yielding a remarkable nonlinear amplification of the acceptor emission. On this basis, a prototype of photonic transistor with high nonlinear gain at very low pump energy was achieved. The results will provide a useful enlightenment for the rational design of novel all-optical switches with desired performances.
- Wang, Kang,Zhang, Wenqing,Gao, Zhenhua,Yan, Yongli,Lin, Xianqing,Dong, Haiyun,Zhang, Chunhuan,Zhang, Wei,Yao, Jiannian,Zhao, Yong Sheng
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- Organic Janus Microspheres: A General Approach to All-Color Dual-Wavelength Microlasers
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We propose a general approach for obtaining dual-wavelength organic microlasers in amphiphilic Janus resonators, where hydrophilic and hydrophobic dyes can be spatially separated via polarity-driven encapsulation. Low-threshold dual-wavelength lasing was achieved in a single Janus particle with well-modulated output. This universal approach enables flexibly designing the lasing wavelength of the Janus microlasers in the full visible spectrum by systematically altering the encapsulated laser dyes. Our findings demonstrate a promising route to the photonic integration at the micro-/nanoscale that may lead to the innovation of concepts and device architectures for multifunctional optoelectronic applications.
- Wei, Cong,Du, Yuxiang,Liu, Yingying,Lin, Xianqing,Zhang, Chuang,Yao, Jiannian,Zhao, Yong Sheng
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- Sterically Crowded Trianglimines—Synthesis, Structure, Solid-State Self-Assembly, and Unexpected Chiroptical Properties
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The chiral, triangular-shape hexaimine macrocycles (trianglimines), bearing bulky alkynyl or aryl substituents were synthesized and studied by means of experimental and theoretical methods. The macrocyclization reactions are driven by the extraordinary stability of the trianglimine ring and provided products with high yields. Electrostatic repulsion between imine nitrogen atoms and the substituents forced an anti conformation of the aromatic linkers. Although the DFT-optimized structure of 7 is D3 symmetrical, in the crystal, the macrocycle adopts a bowl-like molecular shape. The macrocycle self-assembles into tail-to-tail dimers by mutual interdigitation of aromatic moieties. In contrast, macrocycle 8 adopts a rigid pillararene-like conformation. The nature of the substituent significantly affects the electronic properties of the linker. As a result, unexpectedly high exciton Cotton effects are observed in the electronic circular dichroism (ECD) spectra. The origin of these effects was subject of an in-depth study.
- Prusinowska, Natalia,Bardziński, Mateusz,Janiak, Agnieszka,Skowronek, Pawe?,Kwit, Marcin
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- Fluorescent material with properties of aggregation-induced emission and piezochromism
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The invention discloses a fluorescent material with properties of aggregation-induced emission and piezochromism. A structural formula of the fluorescent material is as shown in the specification. The fluorescent material is prepared through a simple condensation reaction by taking dicyanomethylene as an electron acceptor. The fluorescent material is high in solubility in common organic solvents but hardly dissolved in water and forms nano aggregates, so that the characteristic of aggregation-induced emission is achieved. By grinding, fluorescence emission wavelength of the fluorescent material moves towards a long wave direction and recovers after fumigation with dichloromethane, so that the property of piezochromism is achieved.
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Paragraph 0044
(2017/02/09)
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- Synthesis and characterizations of novel spindle-like terphenyl-type chromophores for non-linear optical materials
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A series of novel spindle-like terphenyl-type chromophores, based on 2,5-diphenyl-1,4-distyrylbenzene π-conjugating bridge, N,N-dimethyl and triphenyl amino donors, and Tricyanovinyldihydrofuran(TCF), 1,3,3-trimethyl-5- dicyanovinyl-1-cyclohexene (TDC) acceptors, have been synthesized successfully for the first time. And the non-linear optical properties were evaluated by using the finite-field (FF) method. The results show that, the first-order hyperpolarizability of the chromophores increase with the increase of the withdraw ability of the substituent group on the π-conjugating bridge.
- Shi, Zuosen,Zhang, Xiaolong,Yang, Guochun,Su, Zhongmin,Cui, Zhanchen
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experimental part
p. 4110 - 4117
(2011/06/24)
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- Experimental and theoretical studies of 2,5-diphenyl-1,4-distyrylbenzenes with all-cis- And all-trans double bonds: Chemical structure determination and optical properties
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2,5-Diphenyl-1,4-distyrylbenzene (DPDSB) with all-cis (cw-DPDSB) and all-trans double bonds (trans-DPDSB) were synthesized by Wittig reaction and the differences in structural and optical properties between the cis- and trans-isomers are discussed in detail. Both compounds were fully characterized by NMR spectroscopy, FT-IR spectroscopy, x-ray crystallography, differential scanning calorimetry (DSC) and electrochemical methods. X-ray analysis and molecular simulation revealed that the structure of cis-DPDSB obviously deviates from planarity along both the distyrylbenzene and terphenyl directions, and less intermolecular interaction exists in crystal. The cisisomer shows a large blue shift in the absorption spectrum in comparison with that of the trans-isomer, and cyclic voltammetric measurements give bandgaps of 3.16 and 2.97 eV for cis- and trans-DPDSB, respectively. Both compounds show unusually strong blue fluorescence in the solid state, probably due to the weak intermolecular interaction existing in both isomers owing to the large steric hindrance induced by the substituted phenyl groups. DSC experiments determined that both isomers have excellent thermal stability, which indicates that they can be used as active layers to make stable devices. Quantum chemical calculations for the frontier molecular orbital and the cation and anion properties reveal that the HOMO and LUMO are completely localized in the distyrylbenzene direction and the distyrylbenzene segment has more sensitive electroactivity than the terphenyl segment whether it is cis- or trans-DPDSB. Copyright
- Xie, Zengqi,Yang, Bing,Liu, Linlin,Li, Mao,Lin, Dong,Ma, Yuguang,Cheng, Gang,Liu, Shiyong
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p. 962 - 973
(2007/10/03)
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