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排序方式: 共有1898条查询结果,搜索用时 562 毫秒
61.
Dr. Zhihai Li Dr. Manuel Smeu Sepideh Afsari Dr. Yangjun Xing Prof. Mark A. Ratner Prof. Eric Borguet 《Angewandte Chemie (International ed. in English)》2014,53(4):1098-1102
Sensors play a significant role in the detection of toxic species and explosives, and in the remote control of chemical processes. In this work, we report a single‐molecule‐based pH switch/sensor that exploits the sensitivity of dye molecules to environmental pH to build metal–molecule–metal (m‐M‐m) devices using the scanning tunneling microscopy (STM) break junction technique. Dyes undergo pH‐induced electronic modulation due to reversible structural transformation between a conjugated and a nonconjugated form, resulting in a change in the HOMO–LUMO gap. The dye‐mediated m‐M‐m devices react to environmental pH with a high on/off ratio (≈100:1) of device conductivity. Density functional theory (DFT) calculations, carried out under the non‐equilibrium Green’s function (NEGF) framework, model charge transport through these molecules in the two possible forms and confirm that the HOMO–LUMO gap of dyes is nearly twice as large in the nonconjugated form as in the conjugated form. 相似文献
62.
HOMO Stabilisation in π‐Extended Dibenzotetrathiafulvalene Derivatives for Their Application in Organic Field‐Effect Transistors
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Dr. Yan Geng Dr. Raphael Pfattner Antonio Campos Prof. Wei Wang Dr. Olivier Jeannin Dr. Jürg Hauser Dr. Joaquim Puigdollers Prof. Stefan T. Bromley Prof. Silvio Decurtins Prof. Jaume Veciana Prof. Concepció Rovira Dr. Marta Mas‐Torrent Dr. Shi‐Xia Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(50):16672-16679
Three new organic semiconductors, in which either two methoxy units are directly linked to a dibenzotetrathiafulvalene (DB‐TTF) central core and a 2,1,3‐chalcogendiazole is fused on the one side, or four methoxy groups are linked to the DB‐TTF, have been synthesised as active materials for organic field‐effect transistors (OFETs). Their electrochemical behaviour, electronic absorption and fluorescence emission as well as photoinduced intramolecular charge transfer were studied. The electron‐withdrawing 2,1,3‐chalcogendiazole unit significantly affects the electronic properties of these semiconductors, lowering both the HOMO and LUMO energy levels and hence increasing the stability of the semiconducting material. The solution‐processed single‐crystal transistors exhibit high performance with a hole mobility up to 0.04 cm2 V?1 s?1 as well as good ambient stability. 相似文献
63.
Oligosiloxane Functionalized with Pendant (1,3‐Bis(9‐carbazolyl)benzene) (mCP) for Solution‐Processed Organic Electronics
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Dr. Dianming Sun Dr. Zhaomin Yang Dr. Zhongjie Ren Dr. Huihui Li Prof. Martin R. Bryce Prof. Dongge Ma Prof. Shouke Yan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16233-16241
A new oligosiloxane derivative (ODCzMSi) functionalized with the well‐known 1,3‐bis(9‐carbazolyl)benzene (mCP) pendant moiety, directly linked to the silicon atom of the oligosiloxane backbone, has been synthesized and characterized. Compared to mCP, the attachment of the oligosiloxane chain significantly improves the thermal and morphological stabilities with a high decomposition temperature (Td=540 °C) and glass transition temperature (Tg=142 °C). The silicon–oxygen linkage of ODCzMSi disrupts the backbone conjugation and maintains a high triplet energy level (ET=3.0 eV). A phosphorescent organic light‐emitting diode (PhOLED) using iridium bis(4,6‐difluorophenyl)pyridinato‐N,C2 picolinate (FIrpic) as the emitter and ODCzMSi as the host shows a relatively low turn‐on voltage of 5.0 V for solution‐processed PhOLEDs, maximum external quantum efficiency of 9.2 %, and maximum current efficiency of 17.7 cd A?1. The overall performance of this device is competitive with the best reported solution‐processed blue PhOLEDs. Memory devices using ODCzMSi as an active layer exhibit non‐volatile write‐once read‐many‐times (WORM) characteristics with high stability in retention time up to 104 s and a low switch on voltage. This switching behaviour is explained by different stable conformations of ODCzMSi with high or low conductivity states which are obtained under the action of electric field through a π–π stacking alignment of the pendant aromatic groups. These results with both PhOLEDs and memory devices demonstrate that this oligosiloxane–mCP hybrid structure is promising and versatile for high performance solution‐processed optoelectronic applications. 相似文献
64.
Tuning Thiophene with Phosphorus: Synthesis and Electronic Properties of Benzobisthiaphospholes
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Yunyan Qiu Joshua C. Worch Danielle N. Chirdon Aman Kaur Andrew B. Maurer Samuel Amsterdam Christopher R. Collins Prof. Tomislav Pintauer Prof. David Yaron Prof. Stefan Bernhard Prof. Kevin J. T. Noonan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(25):7746-7751
1,4‐Dimercapto‐2,5‐diphosphinobenzene and 3,6‐bis(hexyloxy)‐1,4‐dimercapto‐2,5‐diphosphinobenzene were synthesized and combined with various acid chlorides to obtain a series of benzobisthiaphospholes. Electrochemical and photophysical properties of the substituted benzobisthiaphospholes have been evaluated, and the observed reductions are more facile than the related benzothiaphospholes and 2,6‐diphenylbenzobisthiazole. A benzobisthiaphosphole with C6H4‐p‐CN substituents was reduced at E1/2=?1.08 V (vs. saturated calomel electrode (SCE)). X‐ray diffraction data for several of these phosphorus heterocycles has been obtained, and DFT calculations at the B3LYP level have been performed. 相似文献
65.
Sepideh Afsari Dr. Zhihai Li Prof. Dr. Eric Borguet 《Angewandte Chemie (International ed. in English)》2014,53(37):9771-9774
The conductivity of a single aromatic ring, perpendicular to its plane, is determined using a new strategy under ambient conditions and at room temperature by a combination of molecular assembly, scanning tunneling microscopy (STM) imaging, and STM break junction (STM‐BJ) techniques. The construction of such molecular junctions exploits the formation of highly ordered structures of flat‐oriented mesitylene molecules on Au(111) to enable direct tip/π contacts, a result that is not possible by conventional methods. The measured conductance of Au/π/Au junction is about 0.1 Go , two orders of magnitude higher than the conductance of phenyl rings connected to the electrodes by standard anchoring groups. Our experiments suggest that long‐range ordered structures, which hold the aromatic ring in place and parallel to the surface, are essential to increase probability of the formation of orientation‐controlled molecular junctions. 相似文献
66.
Heptagon‐Embedded Pentacene: Synthesis,Structures, and Thin‐Film Transistors of Dibenzo[d,d′]benzo[1,2‐a:4,5‐a′]dicycloheptenes
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Xuejin Yang Danqing Liu Prof. Qian Miao 《Angewandte Chemie (International ed. in English)》2014,53(26):6786-6790
This study presents a new class of conjugated polycyclic molecules that contain seven‐membered rings, detailing their synthesis, crystal structures and semiconductor properties. These molecules have a nearly flat C6‐C7‐C6‐C7‐C6 polycyclic framework with a p‐quinodimethane core. With field‐effect mobilities of up to 0.76 cm2 V?1 s?1 as measured from solution‐processed thin‐film transistors, these molecules are alternatives to the well‐studied pentacene analogues for applications in organic electronic devices. 相似文献
67.
Dr. Ryo Tsunashima Yoshifumi Iwamoto Yusuke Baba Chisato Kato Katsuya Ichihashi Dr. Sadafumi Nishihara Prof. Katsuya Inoue Prof. Katsuya Ishiguro Prof. Yu‐Fei Song Prof. Tomoyuki Akutagawa 《Angewandte Chemie (International ed. in English)》2014,53(42):11228-11231
In a mixed‐valence polyoxometalate, electrons are usually delocalized within the cluster anion because of low level of inter‐cluster interaction. Herein, we report the structure and electrical properties of a single crystal in which mixed‐valence polyoxometalates were electrically wired by cationic π‐molecules of tetrathiafulvalene substituted with pyridinium. Electron‐transport characteristics are suggested to represent electron hopping through strong interactions between cluster and cationic π‐molecules. 相似文献
68.
Haipeng B. Li Behabitu E. Tebikachew Cedrik Wiberg Kasper Moth-Poulsen Joshua Hihath 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(28):11738-11743
The exponential proliferation of data during the information age has required the continuous exploration of novel storage paradigms, materials, and devices with increasing data density. As a step toward the ultimate limits in data density, the development of an electrically controllable single-molecule memristive element is reported. In this device, digital information is encoded through switching between two isomer states by applying a voltage signal to the molecular junction, and the information is read out by monitoring the electrical conductance of each isomer. The two states are cycled using an electrically controllable local-heating mechanism for the forward reaction and catalyzed by a single charge-transfer process for the reverse switching. This single-molecule device can be modulated in situ, is fully reversible, and does not display stochastic switching. The I–V curves of this single-molecule system also exhibit memristive character. These features suggest a new approach for the development of molecular switching systems and storage-class memories. 相似文献
69.
Pauline Jaumaux Qi Liu Dr. Dong Zhou Xiaofu Xu Tianyi Wang Yizhou Wang Feiyu Kang Prof. Baohua Li Prof. Guoxiu Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(23):9219-9227
The deployment of high-energy-density lithium-metal batteries has been greatly impeded by Li dendrite growth and safety concerns originating from flammable liquid electrolytes. Herein, we report a stable quasi-solid-state Li metal battery with a deep eutectic solvent (DES)-based self-healing polymer (DSP) electrolyte. This electrolyte was fabricated in a facile manner by in situ copolymerization of 2-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-yl)ureido)ethyl methacrylate (UPyMA) and pentaerythritol tetraacrylate (PETEA) monomers in a DES-based electrolyte containing fluoroethylene carbonate (FEC) as an additive. The well-designed DSP electrolyte simultaneously possesses non-flammability, high ionic conductivity and electrochemical stability, and dendrite-free Li plating. When applied in Li metal batteries with a LiMn2O4 cathode, the DSP electrolyte effectively suppressed manganese dissolution from the cathode and enabled high-capacity and a long lifespan at room and elevated temperatures. 相似文献
70.
AbstractA metal-free and base-free strategy was developed in DES to synthesize styrenes for the first time by decarboxylation of cinnamic acid derivatives, which provided a renewable and cost efficiently protocol to access various styrenes including those with functional groups such as 4-vinylphenol and 1-chloro-4-vinylbenzene. 相似文献