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Chen L.,South China University of Technology | Jiang Y.,Hong Kong University of Science and Technology | Nie H.,South China University of Technology | Hu R.,South China University of Technology | And 6 more authors.
ACS Applied Materials and Interfaces | Year: 2014

In this work, two tailored luminogens (TPE-NB and TPE-PNPB) consisting of tetraphenylethene (TPE), diphenylamino, and dimesitylboryl as a Ï-conjugated linkage, electron donor, and electron acceptor, respectively, are synthesized and characterized. Their thermal stabilities, photophysical properties, solvachromism, fluorescence decays, electronic structures, electrochemical behaviors, and electroluminescence (EL) properties are investigated systematically, and the impacts of electron donor-acceptor (D-A) interaction on optoelectronic properties are discussed. Due to the presence of a TPE unit, both luminogens show aggregation-induced emission, but strong D-A interaction causes a decrease in emission efficiency and red-shifts in photoluminescence and EL emissions. The luminogen, TPE-PNPB, with a weak D-A interaction fluoresces strongly in solid film with a high fluorescence quantum yield of 94%. The trilayer OLED [ITO/NPB (60 nm)/TPE-PNPB (20 nm)/TPBi (40 nm)/LiF (1 nm)/Al (100 nm)] utilizing TPE-PNPB as a light emitter shows a peak luminance of 49a"‰993 cd m-2 and high EL efficiencies up to 15.7 cd A-1, 12.9 lm W-1, and 5.12%. The bilayer OLED [ITO/TPE-PNPB (80 nm)/TPBi (40 nm)/LiF (1 nm)/Al (100 nm)] adopting TPE-PNPB as a light emitter and hole transporter simultaneously affords even better EL efficiencies of 16.2 cd A-1, 14.4 lm W-1, and 5.35% in ambient air, revealing that TPE-PNPB is an eximious p-type light emitter. © 2014 American Chemical Society. Source


Xia H.,Chinese University of Hong Kong | Liu D.,Chinese University of Hong Kong | Xu X.,Chinese University of Hong Kong | Miao Q.,Chinese University of Hong Kong | Miao Q.,Institute of Molecular Functional Materials
Chemical Communications | Year: 2013

Reported here are a new group of cyclopent[hi]aceanthrylene derivatives, which have a cyclopentadiene moiety to accept electrons and thus function as ambipolar organic semiconductors in thin film transistors. © 2013 The Royal Society of Chemistry. Source


Li J.,Hong Kong Polytechnic University | Yan F.,Hong Kong Polytechnic University | Miao Q.,Chinese University of Hong Kong | Miao Q.,Institute of Molecular Functional Materials
Chemistry of Materials | Year: 2010

Quinones are well-known as organic oxidizing reagents in organic synthesis and biological systems, but their ability of accepting electrons was rarely explored in connection with n-type organic semiconductors. Here, we report a comprehensive study on two groups of π-deficient pentacenequinones, fluorinated pentacenequinones and N-heteropentacenequinones, highlighting their electronic structures,molecular packing, and n-channel thin film transistors. It is found that replacingH atoms of pentacenequinone with F atoms or replacing C atoms with N can lower the lowest unoccupied molecular orbital (LUMO) energy level of pentacenequinone to yield n-type organic semiconductors with the field effect mobility up to higher than 0.1 cm2V-1s-1 in thin film transistors. A comparison between the two groups of quinones in terms of their electronic structures and molecular packing has led to interesting findings on the roles of electron-withdrawing moieties in tuning frontier molecular orbitals and p-stacking. Another interesting finding on the molecular packing is the quadruple weak hydrogen bonds, which link the neighboring p-stacks of quinones. This study suggests that π-deficient quinones would be a general design for n-type organic semiconductors. ©2010 American Chemical Society. Source


Xuan S.,Institute of Molecular Functional Materials | Xuan S.,Hefei University of Technology | Wang F.,Institute of Molecular Functional Materials | Wang Y.-X.J.,Interventional Imaging | And 3 more authors.
ACS Applied Materials and Interfaces | Year: 2011

This article reports the fabrication of mesoporous Fe3O 4 nano/microspheres with a high surface area value (163 m 2/g, Brunauer-Emmett-Teller) and demonstrates their use for drug loading, release, and magnetic resonance imaging (MRI). These monodispersed, mesoporous Fe3O4 nano/microspheres with controllable average sizes ranging from 50 to 200 nm were synthesized using a Fe 3O4/poly(acrylic acid) hybrid sphere template and subsequent silica shell formation and removal. We found that the SiO2 coating is a crucial step for the successful synthesis of uniform mesoporous Fe3O4 nano/microspheres. The as-synthesized mesoporous Fe3O4 nanospheres show a high magnetic saturation value (Ms = 48.6 emu/g) and could be used as MRI contrast agents (r 2 = 36.3 s-1 mM-1). Trypan blue exclusion and MTT assay (see Supporting Information) cytotoxicity analyses of the nanospheres based on HepG2 and MDCK cells showed that the products were biocompatible, with a lower toxicity than lipofectamine (positive control). Hydrophilic ibuprofen and hydrophobic zinc(II) phthalocyanine drug loading into mesoporous Fe 3O4 nanospheres and selected release experiments were successfully achieved. The potential use of mesoporous Fe3O 4 nanospheres in biomedical applications, in light of the nano/microspheres' efficient drug loading and release, MRI, and low cytotoxicity, has been demonstrated. It is envisaged that mesoporous Fe 3O4 nanospheres can be used as drug carriers and MRI contrast agents for the reticuloendothelial system; they can also be delivered locally, such as via a selective catheter. © 2011 American Chemical Society. Source


Vreshch V.,CNRS Chemistry Institute of Rennes | Shen W.,CNRS Chemistry Institute of Rennes | Nohra B.,CNRS Chemistry Institute of Rennes | Yip S.-K.,Institute of Molecular Functional Materials | And 5 more authors.
Chemistry - A European Journal | Year: 2012

Treatment of U-shaped, binuclear Cu I complexes 1,1′ (1, counterion: BF 4 -; 1′, counterion: PF 6 -) with metal cyanide linear linkers K[Au(CN) 2] (3) and Hg(CN) 2 (4) lead to formation of new supramolecular assemblies 5,5′ and 6,6′, respectively, in good yield. These derivatives have been characterized by NMR spectroscopy, IR, and X-ray diffraction studies. Derivative 5,5′ are supramolecular metallacycles in which intramolecular aurophilic interactions between the Au I metal centers of the linkers are observed. Derivative 5 crystallizes as a single solid phase, whereas derivative 5′ is characterized in the solid state as four different pseudo-polymorphs (5′a-d). Notably in the case of phase 5′d, a dimer of supramolecular metallacycles bounded by intermolecular aurophilic interactions is formed. Conversely, derivatives 6,6′ present large structural diversity depending on the nature of the counterion. Derivative 6 is a supramolecular rectangle in which the Hg II-Hg II metal distance suggests mercurophilic interaction, whereas 6′ crystallizes as two different pseudo-polymorphs 6′a,b, that is, a one-dimensional coordination polymer and one oligomer with no short Hg II-Hg II metal contacts, respectively. In derivatives 6,6′, short contacts between the Hg II metal centers and fluorine atoms of the counterions are also observed, which may explain the counterion structural dependence of these supramolecular assemblies based on Hg II metal cyanide linker. Comparison of the different solid-state structures characterized highlights the importance of weak secondary interactions between the linkers for the formation supramolecular metallacycles from molecular clips 1,1′ and suggests the range of energies required for these interactions to form metallacycles and to induce self-aggregation. Aurophilicity versus mercurophilicity: The impact of d 10-d 10 metallophilic interactions on the structure of metal-rich supramolecular assemblies has been examined by treating U-shaped binuclear Cu I complexes with linear metal cyanide linkers (metal=Au I, Hg II; see figure). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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