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Find video protocols related to scientific articles indexed in Pubmed.
Two-Dimensional ?-Expanded Quinoidal Terthiophenes Terminated with Dicyanomethylenes as n-Type Semiconductors for High-Performance Organic Thin-Film Transistors.
J. Am. Chem. Soc.
PUBLISHED: 10-29-2014
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Quinoidal oligothiophenes (QOT), as classical n-type semiconductors, have been well-known for a long time but with non-optimal semiconducting properties. We report here the design and selective synthesis of new two-dimensional (2D) ?-expanded quinoidal terthiophenes, 2DQTTs, with proximal (2DQTT-i) and distal (2DQTT-o) regiochemistry for high-performance n-channel organic thin-film transistors (n-OTFTs) featuring high electron mobility, solution processability, and ambient stability. The elegant combination of thieno[3,4-b]thiophene [TT, donor (D)] and 5-alkyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione [TPD, acceptor (A)] units with relatively large ?-surface endows these 2DQTTs with distinctive 2D structural characteristics and flat configuration stabilized by weak intramolecular S-O/S weak interactions. Furthermore, the A-D-A-D-A electronic structure maintains an adequately low LUMO energy level. These 2DQTTs are shown to exhibit outstanding semiconducting properties with electron mobilities of up to 3.0 cm(2) V(-1) s(-1) and on/off ratios of up to 10(6) (2DQTT-o) in ambient- and solution-processed OTFTs. Investigations on thin-film morphology reveal that the microstructure of 2DQTTs is highly dependent on the orientation of the fused thiophene subunits, leading to differences in electron mobilities of 1 order of magnitude. X-ray diffraction studies in particular reveal increased crystallinity, crystalline coherence, and orientational order in 2DQTT-o compared to 2DQTT-i, which accounts for the superior electron transport property of 2DQTT-o.
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Thermoelectric materials: organic thermoelectric materials: emerging green energy materials converting heat to electricity directly and efficiently (adv. Mater. 40/2014).
Adv. Mater. Weinheim
PUBLISHED: 10-24-2014
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Organic conducting materials display great potential to be efficient thermoelectric materials according to the latest reports. On page 6829, W. Xu, D. B. Zhu and co-workers review thermoelectric and related properties of organic conducting materials, including polymers and small molecules, and highlight the most recent progress in materials, measurements, and devices. Prospects for future research are discussed in pursuit of green energy converted by organic thermoelectric materials.
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Effect of molecular asymmetry on the charge transport physics of high mobility n-type molecular semiconductors investigated by scanning Kelvin probe microscopy.
ACS Nano
PUBLISHED: 06-23-2014
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We have investigated the influence of the symmetry of the side chain substituents in high-mobility, solution processable n-type molecular semiconductors on the performance of organic field-effect transistors (OFETs). We compare two molecules with the same conjugated core, but either symmetric or asymmetric side chain substituents, and investigate the transport properties and thin film growth mode using scanning Kelvin probe microscopy (SKPM) and atomic force microscopy (AFM). We find that asymmetric side chains can induce a favorable two-dimensional growth mode with a bilayer structure, which enables ultrathin films with a single bilayer to exhibit excellent transport properties, while the symmetric molecules adopt an unfavorable three-dimensional growth mode in which transport in the first monolayer at the interface is severely hindered by high-resistance grain boundaries.
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Candidate quantum spin liquid due to dimensional reduction of a two-dimensional honeycomb lattice.
Sci Rep
PUBLISHED: 05-30-2014
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As with quantum spin liquids based on two-dimensional triangular and kagome lattices, the two-dimensional honeycomb lattice with either a strong spin-orbital coupling or a frustrating second-nearest-neighbor coupling is expected to be a source of candidate quantum spin liquids. An ammonium salt [(C3H7)3NH]2[Cu2(C2O4)3](H2O)2.2 containing hexagonal layers of Cu(2+) was obtained from solution. No structural transition or long-range magnetic ordering was observed from 290 K to 2 K from single crystal X-ray diffraction, specific heat and susceptibility measurements. The anionic layers are separated by sheets of ammonium and H2O with distance of 3.5 Å and no significant interaction between anionic layers. The two-dimensional honeycomb lattice is constructed from Jahn-Teller distorted Cu(2+) and oxalate anions, showing a strong antiferromagnetic interaction between S = 1/2 metal atoms with ? = -120 (1) K. Orbital analysis of the Cu(2+) interactions through the oxalate-bridges suggests a stripe mode pattern of coupling with weak ferromagnetic interaction along the b axis, and strong antiferromagnetic interaction along the a axis. Analysis of the magnetic susceptibility shows that it is dominated by a quasi-one-dimensional contribution with spin chains that are at least as well isolated as those of well-known quasi-one-dimensional spin liquids.
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Acceptor-donor-acceptor small molecules based on indacenodithiophene for efficient organic solar cells.
ACS Appl Mater Interfaces
PUBLISHED: 05-15-2014
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Four A-D-A type small molecules using 4,4,9,9-tetrakis(4-hexylphenyl)- indaceno[1,2-b:5,6-b']dithiophene as central building block, bithiophene or terthiophene as ?-bridges, alkyl cyanoacetate or rhodanine as end acceptor groups were synthesized and investigated as electron donors in solution-processed organic solar cells (OSCs). These molecules showed excellent thermal stability with decomposition temperatures over 360 °C, relatively low HOMO levels of -5.18 to -5.22 eV, and strong optical absorption from 350 to 670 nm with high molar extinction coefficient of 1.1 × 10(5) to 1.6 × 10(5) M(-1) cm(-1) in chloroform solution. OSCs based on blends of these molecules and PC71BM achieved average power conversion efficiencies of 2.32 to 5.09% (the best 5.32%) after thermal annealing. The effects of thiophene bridge length and end acceptor groups on absorption, energy level, charge transport, morphology, and photovoltaic properties of the molecules were investigated.
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Thieno[3,2-b]thiophene-Diketopyrrolopyrrole-Based Quinoidal Small Molecules: Synthesis, Characterization, Redox Behavior, and n-Channel Organic Field-Effect Transistors.
Chemistry
PUBLISHED: 04-11-2014
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We report the synthesis, characterization, redox behavior, and n-channel organic field-effect (OFET) characteristics of a new class of thieno[3,2-b]thiophene-diketopyrrolopyrrole-based quinoidal small molecules 3 and 4. Under ambient atmosphere, solution-processed thin-film transistors based on 3 and 4 exhibit maximum electron mobilities up to 0.22 and 0.16?cm(2) ?V(-1) ?s(-1) , respectively, with on-off current ratios (Ion /Ioff ) of more than than 10(6) . Cyclic voltammetry analysis showed that this class of quinoidal derivatives exhibited excellent reversible two-stage reduction behavior. This property was further investigated by a stepwise reductive titration of 4, in which sequential reduction to the radical anion and then the dianion were observed.
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Supramolecular association behavior of a strong C60 receptor with conjugated pentacene and tetrathiafulvalene moieties in solution and in the solid state.
Chem. Commun. (Camb.)
PUBLISHED: 03-12-2014
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A ?-extended tetrathiafulvalene (exTTF) containing a conjugated pentacene moiety showed a large binding affinity toward C60 in solution. The crystal structure analysis of the cocrystal formed by this exTTF and C60 revealed that strong ?-? interactions existed between C60 and naphthalene and 1,3-dithiol-2-ylidene units.
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Organic thermoelectric materials: emerging green energy materials converting heat to electricity directly and efficiently.
Adv. Mater. Weinheim
PUBLISHED: 02-11-2014
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The abundance of solar thermal energy and the widespread demands for waste heat recovery make thermoelectric generators (TEGs) very attractive in harvesting low-cost energy resources. Meanwhile, thermoelectric refrigeration is promising for local cooling and niche applications. In this context there is currently a growing interest in developing organic thermoelectric materials which are flexible, cost-effective, eco-friendly and potentially energy-efficient. In particular, the past several years have witnessed remarkable progress in organic thermoelectric materials and devices. In this review, thermoelectric properties of conducting polymers and small molecules are summarized, with recent progresses in materials, measurements and devices highlighted. Prospects and suggestions for future research efforts are also presented. The organic thermoelectric materials are emerging candidates for green energy conversion.
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Specific and reproducible gas sensors utilizing gas-phase chemical reaction on organic transistors.
Adv. Mater. Weinheim
PUBLISHED: 02-08-2014
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Utilizing a textbook reaction on the surface of an organic active channel, achieves sensitive detection of HCl, NH3 and NO2, with good selectivity, excellent reproducibility, and satisfactory stability. These results reveal gas-phase reaction assisted detection as a unique and promising approach to construct practical applicable gas sensors with typical organic transistors.
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A star-shaped perylene diimide electron acceptor for high-performance organic solar cells.
Adv. Mater. Weinheim
PUBLISHED: 02-01-2014
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A novel nonplanar star-shaped perylene diimide acceptor with a triphenylamine core (S(TPA-PDI)) is explored and applied in solution-processed organic solar cells. These solar cells exhibit an encouraging power conversion efficiency of up to 3.32%.
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An easily accessible carbon material derived from carbonization of polyacrylonitrile ultrathin films: ambipolar transport properties and application in a CMOS-like inverter.
Chem. Commun. (Camb.)
PUBLISHED: 01-22-2014
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Ultrathin carbon films were prepared by carbonization of a solution processed polyacrylonitrile (PAN) film in a moderate temperature range (500-700 °C). The films displayed balanced hole (0.50 cm(2) V(-1) s(-1)) and electron mobilities (0.20 cm(2) V(-1) s(-1)) under ambient conditions. Spectral characterization revealed that the electrical transport is due to the formation of sp(2) hybridized carbon during the carbonization process. A CMOS-like inverter demonstrated the potential application of this material in the area of carbon electronics, considering its processability and low-cost.
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Charge-transfer complex crystal based on extended-?-conjugated acceptor and sulfur-bridged annulene: charge-transfer interaction and remarkable high ambipolar transport characteristics.
Adv. Mater. Weinheim
PUBLISHED: 01-05-2014
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A single crystal of a novel mixed-stack donor-acceptor complex formed by a tetracyanoquinodimethane derivative with an extended ?-conjugated system and a sulfur-bridged annulene displays the highest ambipolar transport behavior among donor-acceptor complexes reported with electron and hole mobilities reaching up to 0.24 and 0.77 cm(2) V(-1) s(-1) , respectively.
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Controllable fabrication of ultrathin free-standing graphene films.
Philos Trans A Math Phys Eng Sci
PUBLISHED: 01-01-2014
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Graphene free-standing film-like or paper-like materials have attracted great attention due to their intriguing electronic, optical and mechanical properties and potential application in chemical filters, molecular storage and supercapacitors. Although significant progress has been made in fabricating graphene films or paper, there is still no effective method targeting ultrathin free-standing graphene films (UFGFs). Here, we present a modified filtration assembly method to prepare these ultrathin films. With this approach, we have fabricated a series of ultrathin free-standing graphene oxide films and UFGFs, up to 40?mm in diameter, with controllable thickness from micrometre to nanoscale (approx. 40?nm) dimensions. This method can be easily scaled up and the films display excellent optical, electrical and electrochemical properties. The ability to produce UFGFs from graphene oxide with a scalable, low-cost approach should take us a step closer to real-world applications of graphene.
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Inkjet-printed flexible organic thin-film thermoelectric devices based on p- and n-type poly(metal 1,1,2,2-ethenetetrathiolate)s/polymer composites through ball-milling.
Philos Trans A Math Phys Eng Sci
PUBLISHED: 01-01-2014
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In this article, we put forward a simple method for the synthesis of thermoelectric (TE) composite materials. Both n- and p-type composites were obtained by ball-milling the insoluble and infusible metal coordination polymers with other polymer solutions. The particle size, film morphology and composition were characterized by dynamic light scattering, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. The TE properties of the drop-cast composite film were measured at different temperatures. An inkjet-printed flexible device was fabricated and the output voltage and short-circuit current at various hot-side temperatures (Thot) and temperature gradients (?T) were tested. The composite material not only highly maintained the TE properties of the pristine material but also greatly improved its processability. This method can be extended to other insoluble and infusible TE materials for solution-processed flexible TE devices.
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Tetracyanodibenzotetrathiafulvalene diimides: design, synthesis, and property study.
J. Org. Chem.
PUBLISHED: 11-12-2013
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Tetracyanodibenzotetrathiafulvalene diimide (TCDBTTF-DI), an isomer of core-expanded naphthalene diimides bearing two 2-(1,3-dithiol-2-ylidene)malononitrile moieties (NDI-DTYM2), has been designed and synthesized to explore the effect of its isomeric structure on the optical and electrochemical properties of the materials. UV-vis spectra show that TCDBTTF-DI exhibits variation in its absorption peaks while maintaining a similar optical band gap to NDI-DTYM2. Electrochemical studies indicate that TCDBTTF-DI can not only accept but also lose electrons, in contrast to the solely electron-accepting behavior of NDI-DTYM2.
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Low-temperature, bottom-up synthesis of graphene via a radical-coupling reaction.
J. Am. Chem. Soc.
PUBLISHED: 06-04-2013
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In this article, we demonstrated a method to synthesize graphene films at low temperature via a mild radical-coupling reaction. During the deposition process, with the effectively breaking of the C-Br bonds of hexabromobenzene (HBB) precursors, the generated HBB radicals couple efficiently to form graphene films at the low temperature of 220-250 °C. In situ low-temperature scanning tunneling microscopy was used to provide atomic scale investigation of the graphene growth mechanism using HBB as precursor. The chemical structure evolution during the graphene growth process was further corroborated by in situ X-ray photoelectron spectroscopy measurements. The charge carrier mobility of the graphene film grown at low temperature is at 1000-4200 cm(2) V(-1) s(-1), as evaluated in a field-effect transistor device configuration on SiO2 substrates, indicating the high quality of the films.
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Synthesis of wurtzite Cu2ZnGeSe4 nanocrystals and their thermoelectric properties.
Chem Asian J
PUBLISHED: 03-28-2013
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An unusual wurtzite phase of Cu2ZnGeSe4 (CZGSe) has been discovered and its corresponding nanocrystals (NCs) were synthesized by using a facile hot-injection solution-phase synthesis method. Moreover, the formation mechanism of this new phase of CZGSe, instead of the typically observed stannite structure, has been investigated in detail, which indicates that wurtzite CZGSe, which represents the kinetic phase, could be prepared by using a kinetic growth process without phase transformation into the thermodynamically stable stannite structure during the colloidal synthesis. In addition, the potential of wurtzite CZGSe as a thermoelectric material is demonstrated by characterizing the thermoelectric properties of as-synthesized wurtzite CZGSe NCs. This work allows for a rational manipulation of the NCs with a desired crystal structure through adjusting the thermodynamics and kinetics without using any additives and, because of its simplicity and versatility, it may be extended to the phase-controlled synthesis of other chalcogenide NCs.
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High-performance organic field-effect transistors based on single and large-area aligned crystalline microribbons of 6,13-dichloropentacene.
Adv. Mater. Weinheim
PUBLISHED: 02-18-2013
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Single and large-area aligned crystalline microribbons of 6,13-dichloropentacene (DCP) are prepared. The ribbons display excellent charge transport properties with a mobility of up to 9.0 cm(2) V(-1) s(-1) in ambient conditions, one of the highest values reported for organic semiconductors. The slipped ?-? stacking with large intermolecular overlap is responsible for the high mobility of DCP ribbons.
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Critical role of alkyl chain branching of organic semiconductors in enabling solution-processed N-channel organic thin-film transistors with mobility of up to 3.50 cm² V(-1) s(-1).
J. Am. Chem. Soc.
PUBLISHED: 01-31-2013
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Substituted side chains are fundamental units in solution processable organic semiconductors in order to achieve a balance of close intermolecular stacking, high crystallinity, and good compatibility with different wet techniques. Based on four air-stable solution-processed naphthalene diimides fused with 2-(1,3-dithiol-2-ylidene)malononitrile groups (NDI-DTYM2) that bear branched alkyl chains with varied side-chain length and different branching position, we have carried out systematic studies on the relationship between film microstructure and charge transport in their organic thin-film transistors (OTFTs). In particular synchrotron measurements (grazing incidence X-ray diffraction and near-edge X-ray absorption fine structure) are combined with device optimization studies to probe the interplay between molecular structure, molecular packing, and OTFT mobility. It is found that the side-chain length has a moderate influence on thin-film microstructure but leads to only limited changes in OTFT performance. In contrast, the position of branching point results in subtle, yet critical changes in molecular packing and leads to dramatic differences in electron mobility ranging from ~0.001 to >3.0 cm(2) V(-1) s(-1). Incorporating a NDI-DTYM2 core with three-branched N-alkyl substituents of C(11,6) results in a dense in-plane molecular packing with an unit cell area of 127 Å(2), larger domain sizes of up to 1000 × 3000 nm(2), and an electron mobility of up to 3.50 cm(2) V(-1) s(-1), which is an unprecedented value for ambient stable n-channel solution-processed OTFTs reported to date. These results demonstrate that variation of the alkyl chain branching point is a powerful strategy for tuning of molecular packing to enable high charge transport mobilities.
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Nonsymmetrical dithienylethenes bearing dithieno[3,2-b:2,3-d]thiophene units with photochromic performance in the crystalline phase.
Chemistry
PUBLISHED: 01-17-2013
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Four novel nonsymmetrical photochromic diarylethene compounds containing dithieno[3,2-b:2,3-d]thiophene units were designed and synthesized to investigate their photochromic properties. All these molecules adopt a photoactive antiparallel conformation in single crystals, as revealed by X-ray crystallographic analysis, and exhibit excellent photochromism in solution as well as in the crystalline phase.
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Fullerene/sulfur-bridged annulene cocrystals: two-dimensional segregated heterojunctions with ambipolar transport properties and photoresponsivity.
J. Am. Chem. Soc.
PUBLISHED: 01-02-2013
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Fullerene/sulfur-bridged annulene cocrystals with a two-dimensional segregated alternating layer structure were prepared by a simple solution process. Single-crystal analysis revealed the existence of continuing ?-? interactions in both the donor and acceptor layers, which serve as transport paths for holes and electrons separately. The ambipolar transport behaviors were demonstrated with single-crystal field-effect transistors and rationalized by quantum calculations. Meanwhile, preliminary photoresponsivity was observed with the transistor configuration.
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One-pot synthesis of core-expanded naphthalene diimides: enabling N-substituent modulation for diverse n-type organic materials.
Org. Lett.
PUBLISHED: 12-09-2011
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A mild and versatile one-pot synthesis of core-expanded naphthalene diimides has been developed, which undergoes a nucleophilic aromatic substitution reaction and then an imidization reaction, allowing an easy and low-cost access to diverse n-type organic materials. Some newly synthesized compounds by this one-pot operation exhibited high electron mobility of up to 0.70 cm(2) V(-1) s(-1) in ambient conditions.
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(BEDT-TTF)3Cu2(C2O4)3(CH3OH)2: an organic-inorganic hybrid antiferromagnetic semiconductor.
Chem. Commun. (Camb.)
PUBLISHED: 11-09-2011
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An organic-inorganic hybrid combining a semiconducting BEDT-TTF layer and a Jahn-Teller distorted oxalato-bridged honeycomb antiferromagnetic layer [Cu(2)(C(2)O(4))(3)(2-)](n) was obtained and characterized.
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Oxygen bridged neutral annulenes: a novel class of materials for organic field-effect transistors.
Chem. Commun. (Camb.)
PUBLISHED: 11-04-2011
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New, neutral, meso-substituted tetraoxa[22]annulene[2,1,2,1] aromatic macrocycles are synthesised and disclosed as new p-type semiconductors with reproducible bulk-like carrier mobility (as high as 0.40 cm(2) V(-1) s(-1)) on highly crystalline thin films deposited on octadecyltrichlorosilane modified SiO(2).
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Interface engineering of semiconductor/dielectric heterojunctions toward functional organic thin-film transistors.
Nano Lett.
PUBLISHED: 10-21-2011
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Interface modification is an effective and promising route for developing functional organic field-effect transistors (OFETs). In this context, however, researchers have not created a reliable method of functionalizing the interfaces existing in OFETs, although this has been crucial for the technological development of high-performance CMOS circuits. Here, we demonstrate a novel approach that enables us to reversibly photocontrol the carrier density at the interface by using photochromic spiropyran (SP) self-assembled monolayers (SAMs) sandwiched between active semiconductors and gate insulators. Reversible changes in dipole moment of SPs in SAMs triggered by lights with different wavelengths produce two distinct built-in electric fields on the OFET that can modulate the channel conductance and consequently threshold voltage values, thus leading to a low-cost noninvasive memory device. This concept of interface functionalization offers attractive new prospects for the development of organic electronic devices with tailored electronic and other properties.
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Linear and cyclic tetrathiafulvalene-naphthalenediimide donor-acceptor molecules: metal ions-promoted electron transfer.
J. Org. Chem.
PUBLISHED: 10-03-2011
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Three linear and one cyclic tetrathiafulvalene-1,4,5,8-naphthalenediimide (TTF-NDI) compounds 1, 2, 3, and 4 were synthesized and studied in the presence of metal ions. Both absorption and electron spin resonance spectroscopic studies clearly indicate that electron transfer occurs from TTF to the NDI unit in the presence of metal ions (Pb(2+) and Sc(3+)) for linear compounds 1 and 2. The mechanism based on the metal ion coordination is proposed for the electron transfer within 1 and 2 after the addition of metal ions. Compound 3 exhibits intramolecular charge-transfer absorption because of the cyclophane framework. Interestingly, intramolecular electron transfer also takes place for 3 after the addition of either Sc(3+) or Pb(2+).
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Anthraceno-perylene bisimides: the precursor of a new acene.
Org. Lett.
PUBLISHED: 09-26-2011
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A controlled synthesis strategy for a anthracene-fused perylene bisimide was developed from the cyclization of an anthracene unit pendant to a perylene diimide scaffold. The direct cyclization led to a zigzag molecule, while a Diels-Alder strategy influenced the regiochemistry of cyclization to afford the linear precursor of a new acene.
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A convenient preparation of multi-spectral microparticles by bacteria-mediated assemblies of conjugated polymer nanoparticles for cell imaging and barcoding.
Adv. Mater. Weinheim
PUBLISHED: 05-31-2011
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A novel technique was developed for preparing encoded multicolour microparticles based on the self-assembly of bacteria and conjugated polymer nanoparticles (CPNs) by a very simple and time-saving manner. These bacteria-CPNs microparticles show multicolor emissions by tuning FRET efficiencies among CPNs under single excitation wavelength and can be successfully applied for cell imaging and optical barcoding.
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Mn(C2O4)(H2O)(0.25): an antiferromagnetic oxalato-based cage compound.
Dalton Trans
PUBLISHED: 04-18-2011
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An oxalato-based cage compound Mn(C(2)O(4))(H(2)O)(0.25) was obtained using a solvothermal method. Mn is pentagonal bipyramidal coordinated with O from oxalato with three-atom and one-atom bridges. There are hydrogen bonds between the framework and clathrated H(2)O. A 3D long-range magnetic ordering was observed at 10.9 K.
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A new fluorescence turn-on assay for trypsin and inhibitor screening based on graphene oxide.
ACS Appl Mater Interfaces
PUBLISHED: 03-21-2011
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In this paper, we describe a new continuous fluorescence turn-on method for trypsin assay and inhibitor screening in situ. This assay is designed based on the following assumptions: (1) It is expected that the fluorescein-labeled peptide composed of six arginine residues (Arg(6)-FAM) with positive charges will interact with the negatively charged edge of water-soluble graphene oxide (GO) because of electrostatic interactions to form a GO/Arg(6)-FAM complex. As a result, the fluorescence of fluorescein will be quenched because of the energy transfer from fluorescein to GO. (2) Arg(6)-FAM can be hydrolyzed into small fragments in the presence of trypsin, and accordingly, the GO/Arg(6)-FAM complex will be dissociated, gradually leading to fluorescence recovery for the solution. In this way, the trypsin activity can be easily assayed with the ensemble of Arg(6)-FAM and GO. Additionally, the ensemble can be employed for screening of the inhibitors of trypsin.
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Synthesis of a pentalene centered polycyclic fused system.
Org. Lett.
PUBLISHED: 02-24-2011
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A novel pentalene-centered polycyclic 24?-electron system, IB1, was synthesized via a Pd-catalyzed homocoupling reaction. The geometry structure was studied by X-ray diffraction and theoretical method. The HOMO level of IB1 was studied by electrochemical experiment and DFT methods. The IB1 molecule shows a strong electro-donating property and can form a charge transfer complex with electro-acceptor TCNQ, indicating fascinating potential in the field of organic electronics.
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Linear fused dithieno[2,3-b:32-d]thiophene diimides.
Org. Lett.
PUBLISHED: 02-18-2011
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Linear fused dithieno[2,3-b:32-d]thiophene diimides (DTTDIs, 1-4) were synthesized. Physicochemical investigations suggested that these diimides might be used as potential n-channel organic semiconductors. Single-crystal analysis of N-propyl DTTDI (1) revealed that molecules adopt a layered herringbone packing motif.
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New sulfur bridged neutral annulenes. Structure, physical properties and applications in organic field-effect transistors.
Chem. Commun. (Camb.)
PUBLISHED: 11-15-2010
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New, neutral, meso-substituted tetrathia[22]annulene[2,1,2,1] aromatic macrocyclic architectures display p-type semiconductor behaviour and constitute efficacious molecular field-effect transistors with reproducible bulk-like carrier mobility (as high as 0.63 cm(2) V(-1) S(-1)) on highly crystalline thin films deposited on octadecyltrichlorosilane modified SiO(2).
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A highly sensitive viscosity probe based on ferrocene-BODIPY dyads.
Dalton Trans
PUBLISHED: 09-22-2010
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Two novel ferrocene-BODIPY molecules FcEB and FcB have been synthesized and characterized. An "interlock" packing mode was demonstrated in both FcEB and FcB by analysis of X-ray diffraction data. FcEB exhibits a molecular rotor property with a significant enhancement of quantum yield in viscous solvent. The result shows that the emission of FcEB increased dramatically as the viscosity of solution increased and also confirms that the structure-optical properties can be tuned by the structure design of molecule and introduction of different functional group. Our studies reveal that the system has great potential for developing viscosity probes in biological systems.
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A new tetrathiafulvalene-phenoxynaphthacenequinone dyad: switching on the intramolecular electron-transfer with UV light irradiation and metal ion coordination.
Chem. Commun. (Camb.)
PUBLISHED: 08-19-2010
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The metal ion-promoted intramolecular electron transfer within TTF-based dyad 1 containing a photochromic PNQ unit can be switched on with UV light irradiation by taking advantage of the photochromic feature of the PNQ unit and the fact that the trans and ana forms of PNQ show different electron accepting capacity.
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A biomimetic asymmetric responsive single nanochannel.
J. Am. Chem. Soc.
PUBLISHED: 08-04-2010
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Artificial single nanochannels have emerged as possible candidates for mimicking the process of ionic transport in ion channels and boosting the development of bioinspired intelligent nanomachines for real-world applications, such as biosensors, molecular filtration, and nanofluidic devices. One challenge that remains is to make the artificial nanochannel "smart", with various functions like an organism in Nature. The components of ion channels are asymmetrically distributed between membrane surfaces, which are significant for the implementation of the complex biological function. Inspired by this natural asymmetrical design, here we develop a biomimetic asymmetric responsive single nanochannel system that displays the advanced feature of providing control over pH- and temperature-tunable asymmetric ionic transport properties through asymmetric modifications inside the single nanochannels, which could be considered as a primal platform for the simulation of different ionic transport processes as well as the enhancement of the functionality of ion channels.
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Boron-containing monopyrrolo-annelated tetra thiafulvalene compounds: synthesis and absorption spectral/electrochemical responsiveness toward fluoride ion.
J. Org. Chem.
PUBLISHED: 07-31-2010
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Two new boron-based conjugated compounds 1 and 2 containing one and three monopyrrolo-annelated tetrathiafulvalene (TTF) unit(s) were synthesized and characterized. They exhibit typical ICT absorptions which can be modulated after addition of fluoride ion. In addition, the oxidation potentials of 1 and 2 are shifted to low potential region in the presence of fluoride ion. Such absorption spectral and electrochemical responsiveness of 1 and 2 toward fluoride ion is due to the binding of the boron units with fluoride ion.
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Isolation by crystallization of translational isomers of a bistable donor-acceptor [2]catenane.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 07-27-2010
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The template-directed synthesis of a bistable donor-acceptor [2]catenane wherein both translational isomers--one in which a tetrathiafulvalene unit in a mechanically interlocked crown ether occupies the cavity of a cyclobis(paraquat-p-phenylene) ring and the other in which a 1,5-dioxynaphthalene unit in the crown ether resides inside the cavity of the tetracationic cyclophane--exist in equilibrium in solution, has led to the isolation and separation by hand picking of single crystals colored red and green, respectively. These two crystalline co-conformations have been characterized separately at both the molecular and supramolecular levels, and also by dynamic NMR spectroscopy in solution where there is compelling evidence that the mechanically interlocked molecules are present as a complex mixture of translational, configurational, and conformational isomers wherein the isomerization is best described as being a highly dynamic and adaptable phenomenon.
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Self-assembly of indolocarbazole-containing macrocyclic molecules.
Org. Biomol. Chem.
PUBLISHED: 07-12-2010
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A successful approach for the synthesis of indolocarbazole-containing macrocycles based upon pi-pi stacking preorganization of indolocarbazole planes and click-chemistry reactions has been developed. The macrocycles are able to form folded structures with the help of hydrogen-bonding and pi-pi stacking interactions. Two of the receptors were successfully characterized by single-crystal X-ray diffraction analysis. Our results confirmed that they showed different interesting self-assembly with the anions due to the N-H...X(-) and the triazole C-H...X(-) hydrogen-bonding.
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High quality graphene with large flakes exfoliated by oleyl amine.
Chem. Commun. (Camb.)
PUBLISHED: 06-30-2010
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Large-flake graphene membranes up to 300 microm(2) can be exfoliated from graphite by oleyl amine based on solvothermal conditions. The exfoliated graphene sheets are of high quality and have few defects. The graphene dispersion, predominantly composed of monolayer graphene, had a high concentration of 0.15 mg ml(-1), and can be stabilized against re-aggregation.
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Highly effective protein detection for avidin-biotin system based on colloidal photonic crystals enhanced fluoroimmunoassay.
Biosens Bioelectron
PUBLISHED: 06-18-2010
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There has been immense interest in both instruments and methods to enhance fluorescence signal and achieve highly sensitive fluoroimmunoassay (FIA). In this paper, we present a facile, low-cost and general method of biotinylated colloidal photonic crystal (PC) to improve the FIA of avidin (avidin FIA). The fluorescence signal intensity of the avidin FIA on the colloidal PC can be enhanced over two orders of magnitude relative to the control sample, attributed to the large surface area, resonance field and coherent scattering effect of the colloidal PC. The detection limit is shrunk to 1/69 of that of the control sample. Furthermore, the signal to interference ratio (S/I ratio) is increased because the band-edge induced fluorescence enhancement is wavelength-selective. The interference fluorescence does not go up proportionally while the signal is significantly enhanced by the colloidal PCs. It is believed that the colloidal PC modified with biotin can act as an effective material for a general and sensitive fluoroimmunoassay.
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A new ex-TTF-based organogelator: formation of organogels and tuning with fullerene.
Langmuir
PUBLISHED: 05-29-2010
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A new ex-TTF-based organogelator with L-glutamide-derived lipid unit (compound 1) was synthesized and characterized. The resulting transparent organogels can be obtained with several organic solvents such as toluene, DMSO, and ethanol. It is interesting that its gelation ability can be further enhanced by addition of C(60). The (1)H NMR and absorption spectral studies indicate that the intermolecular interaction between the ex-TTF unit in 1 and C(60) may be responsible for this phenomenon. Further studies imply that the assembly structures in the gel phases in the absence and presence of C(60) may be different. Additionally, organogels can also be prepared with compound 1 and PCBM, and the corresponding xerogel was used to modify ITO electrode. A stable and rapid photocurrent was generated after exposure of the modified ITO electrode to light. This may provide an alternative way for photocurrent generation with high energy conversion efficiency.
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A direct continuous fluorometric turn-on assay for monoamine oxidase B and its inhibitor-screening based on the abnormal fluorescent behavior of silole.
Analyst
PUBLISHED: 05-27-2010
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As essential enzymes in the body, monoamine oxidases (MAOs), including MAO-B, help maintain the proper balance of neurotransmitters and other dietary and biogenic amines. Thus, development of convenient and continuous assays for MAO-B and its inhibitor-screening is highly desirable since the inhibitors have implications for therapeutics for many brain diseases. In this paper, we report a direct continuous fluorescence turn-on assay for MAO-B and its inhibitor-screening with the ensemble of silole 1, heptylamine and HSO(3)(-), which are either easily accessible or commercially available. Fluorescent spectral investigations show that this fluorometric assay can be performed continuously in aqueous solution and MAO-B of concentrations as low as 0.25 microg/mL can be analyzed. Moreover, the ensemble of silole 1, heptylamine, HSO(3)(-) and MAO-B can be employed to screen the inhibitors of MAO-B.
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A new label-free continuous fluorometric assay for trypsin and inhibitor screening with tetraphenylethene compounds.
Org. Lett.
PUBLISHED: 04-22-2010
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A new label-free continuous assay with the ensemble of compound 1 and Arg(6) for trypsin and inhibitor screening was successfully developed by taking advantage of the aggregation-induced emission feature of tetraphenylethene compounds. Both CLSM and DLS studies confirm the formation of the aggregation complex of compound 1 and Arg(6) and disassembly after further addition of trypsin.
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Nanogap electrodes.
Adv. Mater. Weinheim
PUBLISHED: 03-11-2010
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Nanogap electrodes (namely, a pair of electrodes with a nanometer gap) are fundamental building blocks for the fabrication of nanometer-sized devices and circuits. They are also important tools for the examination of material properties at the nanometer scale, even at the molecular scale. In this review, the techniques for the fabrication of nanogap electrodes, the preparation of assembled devices based on the nanogap electrodes, and the potential application of these nanodevices for analysis of material properties are introduced. The history, the research status, and the prospects of nanogap electrodes are also discussed.
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Water-soluble fluorescent conjugated polymers and their interactions with biomacromolecules for sensitive biosensors.
Chem Soc Rev
PUBLISHED: 03-05-2010
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Over the past decades, water-soluble conjugated polymers (CPs) have gained increasing attention as optical platforms for sensitive detection of biomacromolecules (DNA, protein and cell) due to the amplification of fluorescent signals. To meet the requirement for high throughput assays, chip and microarray techniques based on CPs have also been developed. Very recently, fluorescence imaging in vivo and at the cellular level have also been successfully accomplished using these water-soluble CPs. In this tutorial review, we provide a brief review of the synthesis and optical properties of CPs, focusing especially on their applications in biosensors and cell imaging.
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Core-expanded naphthalene diimides fused with 2-(1,3-dithiol-2-ylidene)malonitrile groups for high-performance, ambient-stable, solution-processed n-channel organic thin film transistors.
J. Am. Chem. Soc.
PUBLISHED: 03-02-2010
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A new class of n-type semiconductors for organic thin film transistors (OTFTs), based on core-expanded naphthalene diimides fused with 2-(1,3-dithiol-2-ylidene)malonitrile groups, is reported. The first two representatives of these species, derived from long branched N-alkyl chains, have been successfully used as active layers for high-performance, ambient-stable, solution-processed n-channel OTFTs. Their bottom-gate top-contact devices fabricated by spin-coating methods exhibit high electron mobilities of up to 0.51 cm(2) V(-1) s(-1) with current on/off ratios of 10(5)-10(7), and small threshold voltages below 10 V under ambient conditions. As this class of n-type organic semiconductors has relatively low-lying LUMO levels and good film-formation ability, they also displayed good environmental stability even with prolonged exposure to ambient air. Both the device performance and the ambient stability are among the best for n-channel OTFTs reported to date.
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Multistimuli responsive organogels based on a new gelator featuring tetrathiafulvalene and azobenzene groups: reversible tuning of the gel-sol transition by redox reactions and light irradiation.
J. Am. Chem. Soc.
PUBLISHED: 02-18-2010
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For the development of multistimuli responsive organogels, the new organic gelator LMWG 1, featuring electroactive TTF and photoresponsive azobenzene groups, was designed and studied. By manipulating the redox state of the TTF group in LMWG 1, the gel-sol transition for organogels with the LMWG 1 can be reversibly tuned by either chemical or electrochemical oxidation/reduction reactions. Alternatively, the photoisomerization of the azobenzene group in LMWG 1 can also trigger the gel-sol transition. Therefore, organogels with LMWG 1 respond not only to thermal stimuli but also to redox reactions and light irradiation.
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Current rectification in temperature-responsive single nanopores.
Chemphyschem
PUBLISHED: 02-09-2010
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Herein we demonstrate a fully abiotic smart single-nanopore device that rectifies ionic current in response to the temperature. The temperature-responsive nanopore ionic rectifier can be switched between a rectifying state below 34 degrees C and a non-rectifying state above 38 degrees C actuated by the phase transition of the poly(N-isopropylacrylamide) [PNIPAM] brushes. On the rectifying state, the rectifying efficiency can be enhanced by the dehydration of the attached PNIPAM brushes below the LCST. When the PNIPAM brushes have sufficiently collapsed, the nanopore switches to the non-rectifying state. The concept of the temperature-responsive current rectification in chemically-modified nanopores paves a new way for controlling the preferential direction of the ion transport in nanofluidics by modulating the temperature, which has the potential to build novel nanomachines with smart fluidic communication functions for future lab-on-chip devices.
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Construction and photophysical properties of organic-inorganic nanonetworks based on oligo(phenylenevinylene) and functionalized gold nanoparticles.
Chemphyschem
PUBLISHED: 01-20-2010
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Novel organic-inorganic nanonetworks of oligo(phenylenevinylene) (OPV) and gold nanoparticles (GNPs) have been synthesized by the amine-based epoxide ring-opening reaction. The resulting OPV-GNPs nanocomposites exhibit homogeneous and well-defined interfaces between the organic ligands and the inorganic nanoparticles, thereby promoting efficient electronic interfacial interaction between the two constituents. The functionalized gold nanoparticles serve as chemical reagents for the construction of nanohybrids, while the epoxide-terminated OPV acts as linkage between gold nanoparticles. The new architecture provides a facile methodology for fabrication of novel organic-inorganic nanohybrids under relatively mild conditions, which facilitates further applications of hybrid materials.
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The configuration, solvatochromism and metallo-responses of two novel cyano-containing oligo(phenylene-vinylene) derivatives.
Luminescence
PUBLISHED: 01-14-2010
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Two novel cyano-containing oligo(phenylenevinylene) (OPV) derivatives have been designed and synthesized. Photophysical and sensing properties of the two compounds were studied. Such studies reveal the intramolecular charge transfer process between cyano groups and OPV core. The results showed that the alkyl difference of substituted OPV leads to the changes of molecular configuration and metallo-response of two compounds.
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Micro- and nanocrystals of organic semiconductors.
Acc. Chem. Res.
PUBLISHED: 01-14-2010
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Organic semiconductors have attracted wide attention in recent decades, resulting in the rapid development of organic electronics. For example, the solution processibility of organic semiconductors allows researchers to use unconventional deposition methods (such as inkjet printing and stamping) to fabricate large area devices at low cost. The mechanical properties of organic semiconductors also allow for flexible electronics. However, the most distinguishing feature of organic semiconductors is their chemical versatility, which permits the incorporation of functionalities through molecular design. However, key scientific challenges remain before organic electronics technology can advance further, including both the materials low charge carrier mobility and researchers limited knowledge of structure-property relationships in organic semiconductors. We expect that high-quality organic single crystals could overcome these challenges: their purity and long-range ordered molecular packing ensure high device performance and facilitate the study of structure-property relationships. Micro- and nanoscale organic crystals could offer practical advantages compared with their larger counterparts. First, growing small crystals conserves materials and saves time. Second, devices based on the smaller crystals could maintain the functional advantages of larger organic single crystals but would avoid the growth of large crystals, leading to the more efficient characterization of organic semiconductors. Third, the effective use of small crystals could allow researchers to integrate these materials into micro- and nanoelectronic devices using a "bottom-up" approach. Finally, unique properties of crystals at micro- and nanometer scale lead to new applications, such as flexible electronics. In this Account, we focus on organic micro- and nanocrystals, including their design, the controllable growth of crystals, and structure-property studies. We have also fabricated devices and circuits based on these crystals. This interdisciplinary work combines techniques from the fields of synthetic chemistry, self-assembly, crystallography, and condensed matter physics. We have designed new molecules, including a macrocycle and polyaromatic compounds that self-assemble in a predictive manner into regular high-quality crystals. We have examined how the structure, particularly pi-pi interactions, determines the crystal growth and how the external conditions affect the crystal morphology. We have developed new methods, such as the gold wire mask, the organic ribbon mask, and the gold layer stamp techniques, to fabricate high-performance devices based on the small crystals and investigate their anisotropic charge transport properties. In addition, we have demonstrated small-crystal organic circuits that function with high performance and ultralow power consumption. We expect that organic micro- and nanocrystals have a bright future in organic electronics.
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A biomimetic zinc activated ion channel.
Chem. Commun. (Camb.)
PUBLISHED: 01-13-2010
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A novel biomimetic zinc activated ion channel was prepared by incorporating a zinc responsive peptide, zinc finger, into a single polymeric nanochannel.
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Architecture of graphdiyne nanoscale films.
Chem. Commun. (Camb.)
PUBLISHED: 01-11-2010
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We have demonstrated a methodology to generate large area graphdiyne films with 3.61 cm(2) on the surface of copper via a cross-coupling reaction using hexaethynylbenzene. The device based on graphdiyne films for measurement of electrical property is fabricated and shows conductivity of 2.516 x 10(-4) S m(-1) indicating a semiconductor property.
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Pi-conjugated molecules with fused rings for organic field-effect transistors: design, synthesis and applications.
Chem Soc Rev
PUBLISHED: 12-08-2009
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Pi-conjugated molecular materials with fused rings are the focus of considerable interest in the emerging area of organic electronics, since the combination of excellent charge carrier mobility and high stability may lead to their practical applications. This tutorial review discusses the synthesis, properties and applications of pi-conjugated organic semiconducting materials, especially those with fused rings. The achievements to date, the remaining problems and challenges, and the key research that needs to be done in the near future are all discussed.
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Field emission from nanorod crystalline films of a strong organic electron donor, tetrathiotetracene.
J Nanosci Nanotechnol
PUBLISHED: 11-14-2009
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A strong electron donor, tetrathiotetracene (TTT), with low ionization potential (6.27 eV), low electron affinity (1.10 eV), high conductivity (up to 10(-5) S/m) and good thermal stability (melting point approximately 375 degrees C) was introduced into field emitters. Nanorod crystalline films of TTT were synthesized by vacuum deposition depending on the strong pi--pi interaction between TTT molecules. The nanorod films exhibited excellent field emission properties with a turn-on field of 11.1-11.3 V/microm, a maximum current density of 5.0-7.1 mA/cm2 at an applied field of 25 V//microm, which indicated great potential for field emission application of the strong organic electron donor, TTT.
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Fused-ring pyrazine derivatives for n-type field-effect transistors.
ACS Appl Mater Interfaces
PUBLISHED: 11-12-2009
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Three new fused-ring pyrazine derivatives end-functionalized with trifluoromethylphenyl groups have been synthesized. The effect of a fused-ring pyrazine core on the thermal, electronic, optical, thin film morphology, and organic field-effect transistor (OFET) properties was investigated both experimentally and theoretically. Electrochemistry measurements and density functional theory calculations suggest that the pyrazine core plays a significant role in tuning the electron affinities of these compounds. The optical absorption and fluorescence properties are also sensitive to the pyrazine core. The OFET devices based on the fused-ring pyrazine compounds exhibit electron mobilities as high as ca. 0.03 cm(2) V(-1) s(-1) under nitrogen, and their performance is sensitive to the pyrazine core. The larger pyrazine core leads to a lower LUMO level and lower reorganization energy, to more ordered thin film morphology with larger grain size, and finally to higher mobilities.
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Aggregation-enhanced emission in gold nanoparticles protected by tetradentate perylene derivative.
Langmuir
PUBLISHED: 09-04-2009
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Three novel gold nanoparticle (AuNPs) composites protected by perylene bisimide derivatives have been designed and synthesized. Thanks to the rational molecular design, AuNPs capped by N,N-2,6-bis(4-aminomethylpyridine)-1,6,7,13-tert-[4-(hydroxymethyl)phenoxy-5-(1,2-dithiolan-3-yl)pentanoate]-3,4,9,10- tetracarboxylic acid bisimide (8SP-AuNPs) exhibited unusual enhancement in fluorescence intensity, while the other two nanoparticle composites showed slight enhancement or quench in emission spectra. The structural effect of ligands on aggregation enhanced emission had been studied, and temperature dependence experiments had been conducted. Deductive explanation had been made to elucidate the special spectral behavior of 8SP-AuNPs led by restricted motion of perylene chromophores in the packed nanoclusters.
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A fluorescence "turn-on" ensemble for acetylcholinesterase activity assay and inhibitor screening.
Org. Lett.
PUBLISHED: 08-28-2009
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By making use of the aggregation-induced emission feature of compound 1 and the cascade reactions among acetylthiocholine iodide (ATC), AChE, and compound 2, a new fluorescence "turn-on" method is developed for AChE assay and inhibitor-screening.
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Langmuir-Blodgett monolayer as an efficient p-conducting channel of ambipolar organic transistors and a template for n-type molecular alignment.
Langmuir
PUBLISHED: 08-27-2009
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The Langmuir-Blodgett (LB) technique was used to deposit a monolayer on the gate insulator to identify the role of the monolayer in the organic transistors. Ambipolar transistors were obtained on the basis of the CuPc LB monolayer and F16CuPc films. The results proved that a single molecular layer is enough to show field-effect performance. Moreover, the preorganized LB monolayer led to the alignment of subsequent molecules deposited on it through intermolecular pi-pi interactions.
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Interface engineering: an effective approach toward high-performance organic field-effect transistors.
Acc. Chem. Res.
PUBLISHED: 08-04-2009
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By virtue of their excellent solution processibility and flexibility, organic field-effect transistors (OFETs) are considered outstanding candidates for application in low-cost, flexible electronics. Not only does the performance of OFETs depend on the molecular properties of the organic semiconductors involved, but it is also dramatically affected by the nature of the interfaces present. Therefore, interface engineering, a novel approach towards high-performance OFETs, has attracted considerable attention. In this Account, we focus on recent advances in the study of OFET interfaces--including electrode/organic layer interfaces, dielectric/organic layer interfaces, and organic/organic layer interfaces--that have resulted in improved device performance, enhanced stability, and the realization of organic light-emitting transistors. The electrode/organic layer interface, one of the most important interfaces in OFETs, usually determines the carrier injection characteristics. Focusing on OFETs with copper and silver electrodes, we describe effective modification approaches of the electrode/organic layer interfaces. Furthermore, the influence of electrode morphology on device performance is demonstrated. These results provide novel approaches towards high-performance, low-cost OFETs. The dielectric/organic layer interface is a vital interface that dominates carrier transport; modification of this interface therefore offers a general way to improve carrier transport accordingly. The dielectric layer also affects the device stability of OFETs. For example, high-performance pentacene OFETs with excellent stability are obtained by the selection of a dielectric layer with an appropriate surface energy. The organic/organic layer interface is a newly investigated topic in OFETs. Introduction of organic/organic layer interfaces, such as heterojunctions, can improve device performance and afford ambipolar OFETs. By designing laterally arranged heterojunctions made of organic field-effect materials and light-emitting materials, we realized both light emission and field effects simultaneously in a single OFET. The preceding decade has seen great progress in OFETs. Interface engineering provides a simple but effective approach toward creating high-performance OFETs and will continue to make essential contributions in the development of useful OFET-based devices. The exploration of novel interface engineering applications also merits further attention; the design of gas sensors through a more complete understanding of interface phenomena serves as just one example.
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Heterocyclic annelated di(perylene bisimide): constructing bowl-shaped perylene bisimides by the combination of steric congestion and ring strain.
J. Org. Chem.
PUBLISHED: 07-07-2009
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In this paper, we present the synthesis of S- and N-heterocyclic annelated di(perylene bisimide) with extraordinary doubly bowl-shaped structures. The structures of fused PBI bowls confirmed by single-crystal X-ray structure analysis and temperature-dependent (1)H NMR are realized by the introduction of the steric congestion in nonbay regions and by the concurrent formation of the five-membered heterorings strain in bay regions. On the basis of the geometry obtained from the X-ray analysis, the maximum POAV1 pyramidalization angle is found in N-heterocyclic annelated diPBI 7, as large as 4.7 degrees , indicating the formation of two PBI bowls with significant curvatures. Furthermore, to assist the electrochemical and spectroscopic characterization of the two bowl-shaped derivatives and to assess the influence of heteroatoms on the bowl curvature, quantum-chemically optimized atomic structures, electronic properties, and optical signatures were computed with density functional theory.
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Fluorescence logic-signal-based multiplex detection of nucleases with the assembly of a cationic conjugated polymer and branched DNA.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 06-19-2009
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An energy-transfer cascade is generated from a cationic conjugated polymer (PFP) and negatively charged, Y-shaped DNA labeled with three dyes at its termini (fluorescein (Fl), Tex Red, and Cy5). Multistep fluorescence resonance energy transfer regulates the fluorescence intensities of PFP and the dyes. Different types of logic gates can be operated by observing the emission wavelengths of different dyes with multiplex nucleases as inputs.
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Effect of dielectric layers on device stability of pentacene-based field-effect transistors.
Phys Chem Chem Phys
PUBLISHED: 06-11-2009
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We report stable organic field-effect transistors (OFETs) based on pentacene. It was found that device stability strongly depends on the dielectric layer. Pentacene thin-film transistors based on the bare or polystyrene-modified SiO(2) gate dielectrics exhibit excellent electrical stabilities. In contrast, the devices with the octadecyltrichlorosilane (OTS)-treated SiO(2) dielectric layer showed the worst stabilities. The effects of the different dielectrics on the device stabilities were investigated. We found that the surface energy of the gate dielectric plays a crucial role in determining the stability of the pentacene thin film, device performance and degradation of electrical properties. Pentacene aggregation, phase transfer and film morphology are also important factors that influence the device stability of pentacene devices. As a result of the surface energy mismatch between the dielectric layer and organic semiconductor, the electronic performance was degraded. Moreover, when pentacene was deposited on the OTS-treated SiO(2) dielectric layer with very low surface energy, pentacene aggregation occurred and resulted in a dramatic decrease of device performance. These results demonstrated that the stable OFETs could be obtained by using pentacene as a semiconductor layer.
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New cholesterol-based gelators with maleimide unit and the relevant Michael adducts: chemoresponsive organogels.
Langmuir
PUBLISHED: 06-11-2009
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Compound 1 containing cholesteryl and maleimide units can gel a few organic solvents such as cyclohexane. It is interesting to note that the gel-sol transition can be triggered by addition of trace amounts of thiol and triethylamine. In this regard, we successfully demonstrate the proof of principle for designing chemoresponsive gels by incorporating the reactive groups into the gelators. Additionally, the Michael adducts 2 and 3 were prepared. Compounds 2 and 3 can also gel several organic solvents. The results also show that slight molecular structural variation has a large effect on the gelation ability of the compound. These organogels were characterized with SEM, AFM, CD, and XRD. Interestingly, gelation-induced CD spectra were observed for gels of 1, 2, and 3.
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Single-nucleotide polymorphism (SNP) genotyping using cationic conjugated polymers in homogeneous solution.
Nat Protoc
PUBLISHED: 06-06-2009
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This protocol describes a simple, convenient and sensitive single-nucleotide polymorphism (SNP) genotyping method using an optically amplifying cationic conjugated polymer and single base primer extension reaction. The fluorescence resonance energy transfer (FRET) efficiency between the conjugated polymer (PFP, poly{(1,4-phenylene)-2,7-[9,9-bis(6-N,N,N-trimethyl ammonium)-hexyl fluorene] dibromide}) and a fluorescein-labeled dNTP (dNTP-Fl) is correlated to the incorporation of the dNTP-Fl into an allele-specific primer; incorporation occurs by a single base extension reaction when the target DNA and the primer are complementary at the SNP site. By triggering the FRET from PFP to fluorescein and measuring the change in fluorescence intensity of samples, the SNP genotypes can be discriminated. In comparison with other SNP genotyping methods, this protocol simplifies procedures and improves sensitivity by eliminating the need for primer labeling, cumbersome workups, chemical/enzymatic coupling reactions and sophisticated instruments. The assay takes about 2 h for PCR amplification followed by 5.5-7.5 h to obtain the genotypes.
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Hierarchical assembly of an achiral pi-conjugated molecule into a chiral nanotube through the air/water interface.
Langmuir
PUBLISHED: 05-23-2009
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An achiral pi-conjugated fluorinated fused pyrazine derivative has been spread at the air/water interface, and its assembling property is investigated. It has been found that the compound, although without any long alkyl chain, could be spread as a floating film on water surface, the surface pressure of which can be compressed up to ca. 70 mN/m. An inflection point has been observed in the isotherm of the floating film on water surface. The atomic force microscope (AFM), scanning electron microscope (SEM) as well as the transmission electron microscope (TEM) observations revealed that the floating film first formed a multilayer structure and then was compressed into nanotubes after the inflection region as a result of the rolling of the ultrathin film. Interestingly, the rolled nanotubes show circular dichroism although the molecule itself is an achiral species, suggesting the chiral nanotube is predominantly produced on the water surface. The investigation provides an effective way to fabricate supramolecular-based organic chiral nanotubes through an interfacial supramolecular assembly process.
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A new tetrathiafulvalene-quinone-tetrathiafulvalene triad: modulation of the intramolecular charge transfer by the electron-transfer process promoted by metal ions.
J. Org. Chem.
PUBLISHED: 05-09-2009
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Electron transfer can occur from the TTF units to the substituted quinone unit in a new TTF-quinone-TTF triad 1 containing the N,N-dialkylaniline-substituted quinone unit flanked by two TTF units, in the presence of metal ions (Pb(2+), Zn(2+), and Sc(3+)). Simultaneously, the corresponding charge transfer within the substituted quinone unit becomes weak in the presence of metal ions. Moreover, the metal ion-promoted electron transfer and the intramolecular charge transfer can be tuned by alternating UV and visible light irradiation in the presence of spiropyran.
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Ultra-sensitivity glucose sensor based on field emitters.
Nanoscale Res Lett
PUBLISHED: 05-04-2009
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A new glucose sensor based on field emitter of ZnO nanorod arrays (ZNA) was fabricated. This new type of ZNA field emitter-based sensor shows high sensitivity with experimental limit of detection of 1 nM glucose solution and a detection range from 1 nM to 50 ?M in air at room temperature, which is lower than that of glucose sensors based on surface plasmon resonance spectroscopy, fluorescence signal transmission, and electrochemical signal transduction. The new glucose sensor provides a key technique for promising consuming application in biological system for detecting low levels of glucose on single cells or bacterial cultures.
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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.