共查询到20条相似文献,搜索用时 187 毫秒
1.
Yuuki Komoto Yasuomi Yamazaki Dr. Yusuke Tamaki Madoka Iwane Prof.Dr. Tomoaki Nishino Prof. Dr. Osamu Ishitani Prof. Dr. Manabu Kiguchi Dr. Shintaro Fujii 《化学:亚洲杂志》2018,13(10):1297-1301
Single‐molecule junctions are of particular interest in molecular electronics. To realize molecular electronic devices, it is crucial that functional single‐molecule junctions are connected to each other by using joint units on the atomic scale. However, good joint units have not been reported because controlling the charge transport directions through the junctions is not trivial. Here, we report a joint unit that controls and changes the charge transport directions through the junctions, by using a ruthenium–tris‐bipyridine (RuBpy) complex. The RuBpy single‐molecule junction was fabricated with scanning tunnelling microscopy‐based break junction techniques. The RuBpy single‐molecule junction showed two distinct high and low conductance states. The two states were characterized by the conductance measurement, the correlation analysis, and the comparative experiment of bipyridine (Bpy), which is the ligand unit of RuBpy. We demonstrate that the Ru complex has multiple charge transport paths, where the charge is carried vertically and horizontally through the complex depending on the path. 相似文献
2.
Stefan Ballmann Wolfgang Hieringer Dr. Daniel Secker Dr. Qinglin Zheng John A. Gladysz Prof. Andreas Görling Prof. Heiko B. Weber Prof. 《Chemphyschem》2010,11(10):2256-2260
We investigate the effect of vibrations on the electronic transport through single‐molecule junctions, using the mechanically controlled break junction technique. The molecules under investigation are oligoyne chains with appropriate end groups, which represent both an ideally linear electrical wire and an ideal molecular vibrating string. Vibronic features can be detected as satellites to the electronic transitions, which are assigned to longitudinal modes of the string by comparison with density functional theory data. 相似文献
3.
Ta‐Cheng Ting Dr. Liang‐Yan Hsu Dr. Min‐Jie Huang Er‐Chien Horng Dr. Hao‐Cheng Lu Chan‐Hsiang Hsu Dr. Ching‐Hong Jiang Prof. Bih‐Yaw Jin Prof. Shie‐Ming Peng Prof. Chun‐hsien Chen 《Angewandte Chemie (International ed. in English)》2015,54(52):15734-15738
The use of single‐molecule junctions for various functions constitutes a central goal of molecular electronics. The functional features and the efficiency of electron transport are dictated by the degree of energy‐level alignment (ELA), that is, the offset potential between the electrode Fermi level and the frontier molecular orbitals. Examples manifesting ELA are rare owing to experimental challenges and the large energy barriers of typical model compounds. In this work, single‐molecule junctions of organometallic compounds with five metal centers joined in a collinear fashion were analyzed. The single‐molecule i–V scans could be conducted in a reliable manner, and the EFMO levels were electrochemically accessible. When the electrode Fermi level (EF) is close to the frontier orbitals (EFMO) of the bridging molecule, larger conductance was observed. The smaller |EF?EFMO| gap was also derived quantitatively, unambiguously confirming the ELA. The mechanism is described in terms of a two‐level model involving co‐tunneling and sequential tunneling processes. 相似文献
4.
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
5.
The Synthesis of Functionalised Diaryltetraynes and Their Transport Properties in Single‐Molecule Junctions 下载免费PDF全文
Dr. Murat Gulcur Dr. Pavel Moreno‐García Xiaotao Zhao Masoud Baghernejad Dr. Andrei S. Batsanov Dr. Wenjing Hong Prof. Martin R. Bryce Prof. Thomas Wandlowski 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(16):4653-4660
The synthesis and characterisation is described of six diaryltetrayne derivatives [Ar‐(C?C)4‐Ar] with Ar=4‐NO2‐C6H4‐ ( NO24 ), 4‐NH(Me)C6H4‐ ( NHMe4 ), 4‐NMe2C6H4‐ ( NMe24 ), 4‐NH2‐(2,6‐dimethyl)C6H4‐ ( DMeNH24 ), 5‐indolyl ( IN4 ) and 5‐benzothienyl ( BTh4 ). X‐ray molecular structures are reported for NO24 , NHMe4 , DMeNH24 , IN4 and BTh4 . The stability of the tetraynes has been assessed under ambient laboratory conditions (20 °C, daylight and in air): NO24 and BTh4 are stable for at least six months without observable decomposition, whereas NHMe4 , NMe24 , DMeNH24 and IN4 decompose within a few hours or days. The derivative DMeNH24 , with ortho‐methyl groups partially shielding the tetrayne backbone, is considerably more stable than the parent compound with Ar=4‐NH2C6H4 ( NH24 ). The ability of the stable tetraynes to anchor in Au|molecule|Au junctions is reported. Scanning‐tunnelling‐microscopy break junction (STM‐BJ) and mechanically controllable break junction (MCBJ) techniques are employed to investigate single‐molecule conductance characteristics. 相似文献
6.
Multichannel Conductance of Folded Single‐Molecule Wires Aided by Through‐Space Conjugation 下载免费PDF全文
Long Chen Ya‐Hao Wang Bairong He Han Nie Dr. Rongrong Hu Prof. Fei Huang Prof. Anjun Qin Dr. Xiao‐Shun Zhou Prof. Zujin Zhao Prof. Ben Zhong Tang 《Angewandte Chemie (International ed. in English)》2015,54(14):4231-4235
Deciphering charge transport through multichannel pathways in single‐molecule junctions is of high importance to construct nanoscale electronic devices and deepen insight into biological redox processes. Herein, we report two tailor‐made folded single‐molecule wires featuring intramolecular π–π stacking interactions. The scanning tunneling microscope (STM) based break‐junction technique and theoretical calculations show that through‐bond and through‐space conjugations are integrated into one single‐molecule wire, allowing for two simultaneous conducting channels in a single‐molecule junction. These folded molecules with stable π–π stacking interaction offer conceptual advances in single‐molecule multichannel conductance, and are perfect models for conductance studies in biological systems, organic thin films, and π‐stacked columnar aggregates. 相似文献
7.
Pingchuan Shen Miaoling Huang Jingyu Qian Jinshi Li Siyang Ding Xiao‐Shun Zhou Bin Xu Zujin Zhao Ben Zhong Tang 《Angewandte Chemie (International ed. in English)》2020,59(11):4581-4588
Constructing single‐molecule parallel circuits with multiple conduction channels is an effective strategy to improve the conductance of a single molecular junction, but rarely reported. We present a novel through‐space conjugated single‐molecule parallel circuit (f‐4Ph‐4SMe) comprised of a pair of closely parallelly aligned p‐quaterphenyl chains tethered by a vinyl bridge and end‐capped with four SMe anchoring groups. Scanning‐tunneling‐microscopy‐based break junction (STM‐BJ) and transmission calculations demonstrate that f‐4Ph‐4SMe holds multiple conductance states owing to different contact configurations. When four SMe groups are in contact with two electrodes at the same time, the through‐bond and through‐space conduction channels work synergistically, resulting in a conductance much larger than those of analogous molecules with two SMe groups or the sum of two p‐quaterphenyl chains. The system is an ideal model for understanding electron transport through parallel π‐stacked molecular systems and may serve as a key component for integrated molecular circuits with controllable conductance. 相似文献
8.
Haipeng B. Li Behabitu E. Tebikachew Cedrik Wiberg Kasper Moth‐Poulsen Joshua Hihath 《Angewandte Chemie (International ed. in English)》2020,59(28):11641-11646
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
9.
Feng Jiang Douglas I. Trupp Norah Algethami Haining Zheng Wenxiang He Afaf Alqorashi Chenxu Zhu Chun Tang Ruihao Li Junyang Liu Hatef Sadeghi Jia Shi Ross Davidson Marcus Korb Alexandre N. Sobolev Masnun Naher Sara Sangtarash Paul J. Low Wenjing Hong Colin J. Lambert 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(52):19163-19169
Together with the more intuitive and commonly recognized conductance mechanisms of charge‐hopping and tunneling, quantum‐interference (QI) phenomena have been identified as important factors affecting charge transport through molecules. Consequently, establishing simple and flexible molecular‐design strategies to understand, control, and exploit QI in molecular junctions poses an exciting challenge. Here we demonstrate that destructive quantum interference (DQI) in meta‐substituted phenylene ethylene‐type oligomers (m‐OPE) can be tuned by changing the position and conformation of methoxy (OMe) substituents at the central phenylene ring. These substituents play the role of molecular‐scale taps, which can be switched on or off to control the current flow through a molecule. Our experimental results conclusively verify recently postulated magic‐ratio and orbital‐product rules, and highlight a novel chemical design strategy for tuning and gating DQI features to create single‐molecule devices with desirable electronic functions. 相似文献
10.
Single‐Molecule Spin Switch Based on Voltage‐Triggered Distortion of the Coordination Sphere 下载免费PDF全文
Dr. Gero D. Harzmann Riccardo Frisenda Prof. Dr. Herre S. J. van der Zant Prof. Dr. Marcel Mayor 《Angewandte Chemie (International ed. in English)》2015,54(45):13425-13430
Here, we report on a new single‐molecule‐switching concept based on the coordination‐sphere‐dependent spin state of FeII species. The perpendicular arrangement of two terpyridine (tpy) ligands within heteroleptic complexes is distorted by the applied electric field. Whereas one ligand fixes the complex in the junction, the second one exhibits an intrinsic dipole moment which senses the E field and causes the distortion of the FeII coordination sphere triggering the alteration of its spin state. A series of complexes with different dipole moments have been synthesized and their transport features were investigated via mechanically controlled break‐junctions. Statistical analyses support the hypothesized switching mechanism with increasing numbers of junctions displaying voltage‐dependent bistabilities upon increasing the FeII complexes’ intrinsic dipole moments. A constant threshold value of the E field required for switching corroborates the mechanism. 相似文献
11.
Xiaohui Li Qingqing Wu Jie Bai Songjun Hou Wenlin Jiang Chun Tang Hang Song Xiaojuan Huang Jueting Zheng Yang Yang Junyang Liu Yong Hu Jia Shi Zitong Liu Colin J. Lambert Deqing Zhang Wenjing Hong 《Angewandte Chemie (International ed. in English)》2020,59(8):3280-3286
The experimental investigation of intermolecular charge transport in π‐conjugated materials is challenging. Herein, we describe the investigation of charge transport through intermolecular and intramolecular paths in single‐molecule and single‐stacking thiophene junctions by the mechanically controllable break junction (MCBJ) technique. We found that the ability for intermolecular charge transport through different single‐stacking junctions was approximately independent of the molecular structure, which contrasts with the strong length dependence of conductance in single‐molecule junctions with the same building blocks, and the dominant charge‐transport path of molecules with two anchors transited from an intramolecular to an intermolecular path when the degree of conjugation increased. An increase in conjugation further led to higher binding probability owing to the variation in binding energies, as supported by DFT calculations. 相似文献
12.
Yonghai Li Masoud Baghernejad Al‐Galiby Qusiy David ZsoltManrique Guanxin Zhang Joseph Hamill Yongchun Fu Peter Broekmann Wenjing Hong Thomas Wandlowski Deqing Zhang Colin Lambert 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(46):13790-13793
We studied charge transport through core‐substituted naphthalenediimide (NDI) single‐molecule junctions using the electrochemical STM‐based break‐junction technique in combination with DFT calculations. Conductance switching among three well‐defined states was demonstrated by electrochemically controlling the redox state of the pendent diimide unit of the molecule in an ionic liquid. The electrical conductances of the dianion and neutral states differ by more than one order of magnitude. The potential‐dependence of the charge‐transport characteristics of the NDI molecules was confirmed by DFT calculations, which account for electrochemical double‐layer effects on the conductance of the NDI junctions. This study suggests that integration of a pendant redox unit with strong coupling to a molecular backbone enables the tuning of charge transport through single‐molecule devices by controlling their redox states. 相似文献
13.
Sepideh Afsari Parisa Yasini Haowei Peng John P. Perdew Eric Borguet 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(40):14413-14418
In most junctions built by wiring a single molecule between two electrodes, the electrons flow along only one axis: between the two anchoring groups. However, molecules can be anisotropic, and an orientation‐dependent conductance is expected. Here, we fabricated single‐molecule junctions by using the electrode potential to control the molecular orientation and access individual elements of the conductivity tensor. We measured the conductance in two directions, along the molecular plane as the benzene ring bridges two electrodes using anchoring groups (upright) and orthogonal to the molecular plane with the molecule lying flat on the substrate (planar). The perpendicular (planar) conductance is about 400 times higher than that along the molecular plane (upright). This offers a new method for designing a reversible room‐temperature single‐molecule electromechanical switch that controllably employs the electrode potential to orient the molecule in the junction in either “ON” or “OFF” conductance states. 相似文献
14.
Fadil Iyikanat Prof. Dr. Ramazan T. Senger Prof. Dr. Francois M. Peeters Prof. Dr. Hasan Sahin 《Chemphyschem》2016,17(23):3985-3991
By using density functional theory and non‐equilibrium Green′s function‐based methods, we investigated the electronic and transport properties of a TiS3 monolayer p–n junction. We constructed a lateral p–n junction on a TiS3 monolayer using Li and F adatoms. An applied bias voltage caused significant variability in the electronic and transport properties of the TiS3 p–n junction. In addition, the spin‐dependent current–voltage characteristics of the constructed TiS3 p–n junction were analyzed. Important device characteristics were found, such as negative differential resistance and rectifying diode behaviors for spin‐polarized currents in the TiS3 p–n junction. These prominent conduction properties of the TiS3 p–n junction offer remarkable opportunities for the design of nanoelectronic devices based on a recently synthesized single‐layered material. 相似文献
15.
Chun Tang Lijue Chen Longyi Zhang Zhixin Chen Guopeng Li Zhewei Yan Luchun Lin Junyang Liu Longfeng Huang Yiling Ye Yuhui Hua Jia Shi Haiping Xia Wenjing Hong 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(31):10711-10715
Molecular components are vital to introduce and manipulate quantum interference (QI) in charge transport through molecular electronic devices. Up to now, the functional molecular units that show QI are mostly found in conventional π‐ and σ‐bond‐based systems; it is thus intriguing to study QI in multicenter bonding systems without both π‐ and σ‐conjugations. Now the presence of QI in multicenter‐bond‐based systems is demonstrated for the first time, through the single‐molecule conductance investigation of carborane junctions. We find that all the three connectivities in carborane frameworks show different levels of destructive QI, which leads to highly suppressed single‐molecule conductance in para‐ and meta‐connected carboranes. The investigation of QI into carboranes provides a promising platform to fabricate molecular electronic devices based on multicenter bonds. 相似文献
16.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(7):1856-1860
Fused‐pentagons results in an increase of local steric strain according to the isolated pentagon rule (IPR), and for all reported non‐IPR clusterfullerenes multiple (two or three) metals are required to stabilize the strained fused‐pentagons, making it difficult to access the single‐atom properties. Herein, we report the syntheses and isolations of novel non‐IPR mononuclear clusterfullerenes MNC@C76 (M=Tb, Y), in which one pair of strained fused‐pentagon is stabilized by a mononuclear cluster. The molecular structures of MNC@C76 (M=Tb, Y) were determined unambiguously by single‐crystal X‐ray diffraction, featuring a non‐IPR C 2v (19138)‐C76 cage entrapping a nearly linear MNC cluster, which is remarkably different from the triangular MNC cluster within the reported analogous clusterfullerenes based on IPR‐obeying C82 cages. The TbNC@C76 molecule is found to be a field‐induced single‐molecule magnet (SMM). 相似文献
17.
Observation of Charge Separation and Space‐Charge Region in Single‐Crystal P3HT/C60 Heterojunction Nanowires 下载免费PDF全文
Dr. Kyung Sun Park Ki Seok Lee Jangmi Baek Lynn Lee Byung Hee Son Dr. Yong‐Eun Koo Lee Prof. Yeong Hwan Ahn Prof. Won Il Park Prof. Youngjong Kang Prof. Myung M. Sung 《Angewandte Chemie (International ed. in English)》2016,55(35):10273-10277
We directly observed charge separation and a space‐charge region in an organic single‐crystal p–n heterojunction nanowire, by means of scanning photocurrent microscopy. The axial p–n heterojunction nanowire had a well‐defined planar junction, consisted of P3HT (p‐type) and C60 (n‐type) single crystals and was fabricated by means of the recently developed inkjet‐assisted nanotransfer printing technique. The depletion region formed at the p–n junction was directly observed by exploring the spatial distribution of photogenerated carriers along the heterojunction nanowire under various applied bias voltages. Our study provides a facile approach toward the precise characterization of charge transport in organic heterojunction systems as well as the design of efficient nanoscale organic optoelectronic devices. 相似文献
18.
Wei Wang Rui Sun Jing Guo Jie Guo Jie Min 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(41):14698-14703
A new balanced donor–acceptor molecule, namely, benzodithiophene (BDT)‐rhodanine‐[6,6]‐phenyl‐C71 butyric acid methyl ester (Rh‐PC71BM) comprising two covalently linked blocks, a p‐type oligothiophene‐containing BDT‐based moiety and an n‐type PC71BM unit was designed and synthesized. The single‐component organic solar cell (SCOSC) fabricated from Rh‐PC71BM molecules showed a power conversion efficiency (PCE) of 3.22 % with an open‐circuit voltage (Voc) of 0.98 V. These results rank are among the highest values for SCOSCs based on a monomolecular material. In particular, the one‐molecule Rh‐PC71BM device exhibits excellent thermal stability compared to reference Rh‐OH:PC71BM device. The success of our monomolecular strategy can provide a new way to develop high‐performance SCOSCs. 相似文献
19.
Peng‐Bo Jin Yuan‐Qi Zhai Ke‐Xin Yu Richard E. P. Winpenny Yan‐Zhen Zheng 《Angewandte Chemie (International ed. in English)》2020,59(24):9350-9354
The dicarbollide ion, nido‐C2B9H112? is isoelectronic with cyclopentadienyl. Herein, we make dysprosiacarboranes, namely [(C2B9H11)2Ln(THF)2][Na(THF)5] (Ln=Dy, 1Dy ) and [(THF)3(μ‐H)3Li]2[{η5‐C6H4(CH2)2C2B9H9}Dy{η2:η5‐C6H4(CH2)2C2B9H9}2Li] 3Dy and show that dicarbollide ligands impose strong magnetic axiality on the central DyIII ion. The effective energy barrier (Ueff) for the loss of magnetization can be varied by the substitution pattern on the dicarbollide. This finding is demonstrated by comparing complexes of nido‐C2B9H112? and nido‐[o‐xylylene‐C2B9H9]2?, which show a Ueff of 430(5) K and 804(7) K, respectively. The blocking temperature defined by the open hysteresis temperature of 3Dy reaches 6.8 K. Moreover, the linear complex [Dy(C2B9H11)2]? is predicted to have comparable properties with the linear [Dy(CpMe3)2]+ complex. As such, carboranyl ligands and their derivatives may provide a new type of organometallic ligand for high‐performance single‐molecule magnets. 相似文献
20.
《Chemphyschem》2005,6(11):2404-2409
Herein, we continue our investigation of the single‐molecule spectroscopy of the conjugated polymer poly[2‐methoxy,5‐(2′‐ethylhexyloxy)‐p‐phenylene‐vinylene] (MEH‐PPV) at cryogenic temperatures. First, the low temperature microsecond dynamics of single MEH‐PPV conjugated polymer molecules are compared to the dynamics at room temperature revealing no detectible temperature dependence. The lack of temperature dependence is consistent with the previous assignment of the dynamics to a mechanism that involves intersystem crossing and triplet–triplet annihilation. Second, the fluorescence spectra of single MEH‐PPV molecules at low temperature are studied as a function of excitation wavelength (i.e. 488, 543, and 568 nm). These results exhibit nearly identical fluorescence spectra for different excitation wavelengths. This strongly suggests that electronic energy transfer occurs efficiently to a small number of low‐energy sites in the multichromophoric MEH‐PPV chains. 相似文献