Institute of Chemistry
Changchun Institute of Applied Chemistry, Chinese Academy Of SciencesNot a member yet
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Synthesis and properties of greenish-blue-emitting iridium dendrimers with N-phenylcarbazole-based polyether dendrons by a post-dendronization route
No full textA series of solution processible greenish-blue-emitting Ir dendrimers with polyether dendrons that consist of N-phenylcarbazole (NPC) are developed via a convenient post-dendronization method. It involves two steps: (i) the successful preparation of a reactive Ir core, namely m-HO-dfppyIr, only when the hydroxyl group is located at the meta position relative to the N atom in the C<^>N ligand so as to eliminate the possible resonance structure between enol and keto; and (ii) the subsequent functionalization with NPC-based polyether dendrons to afford the first, second and third generation Ir dendrimers (Ir-G1B, Ir-G2B and Ir-G3B) with ease and high yields over 60%. All these dendritic complexes possess good thermal stability with decomposition temperatures higher than 380 degrees C and glass transition temperatures higher than 200 degrees C. In addition, with the growing generation number, the intermolecular interactions between emissive Ir cores are expected to be effectively inhibited to avoid the luminescence quenching, which is confirmed from the blue-shifted emission peak and the enhanced lifetime of Ir-G3B in the solid state. As a result, on going from Ir-G1B to Ir-G3B, the maximum luminous efficiency rises upward from 4.7 to 9.2 cd A(-1) for nondoped electrophosphorescent devices. Further optimization by doping them into a dendritic H2 host leads to the improved luminous efficiencies as high as 20.0-25.2 cd A(-1)
Temperature-dependent photoluminescence of cadmium-free Cu-Zn-In-S quantum dot thin films as temperature probes
No full textWe reported temperature-dependent photoluminescence (PL) studies on Cu-Zn-In-S quantum dot (QD) thin films. In this paper, cadmium-free and luminescent Cu-Zn-In-S quantum dot thin films were in situ formed by thermal decomposition of molecular-based precursors in the open air, without need of the complicated quantum dot synthesis. Molecular-based precursor solutions were prepared by dissolving Cu2O, ZnO, and In(OH)(3) in the ethanol solution of butylamine and carbon disulfide. The effects of sintering temperature, sintering time, and the concentration of capping agents on the photoluminescence properties of Cu-Zn-In-S QD thin films have been systematically investigated. It was found that alkali metal ions play an important role in enhancing the PL quantum yield of quantum dot thin films. The as-prepared QD thin films show composition-tunable emission in the range of 535 nm to 677 nm, and the absolute PL quantum yields can reach as high as 22.1%. All of the as-deposited QD thin films show a single-exponential decay to temperature, indicating that these cadmium-free QD thin films have high potential as temperature probes
Synthesis of Heterocyclic-Fused Cyclopentadienyl Scandium Complexes and the Catalysis for Copolymerization of Ethylene and Dicyclopentadiene
No full textHeterocyclic-fused cyclopentadienyl scandium bis(alkyl) complexes L1-4Sc(CH2SiMe3)(2)THF ((5-Me-1-Ph-cyclopenta[b]pyrrol-4-yl)Sc(CH2SiMe3)(2)THF (1), (2,5-Me-2-3-Ph-6H-cyclopenta[b]thiophenyl)Sc(CH2SiMe3)(2)THF (2), (2,4,5,6-Me-4-4H-cyclopenta[b]thiophenyl)Sc(CH2SiMe3)(2)THF (3), (2,3,4,5,6-Me-5-4H-cyclopenta[b]thiophenyl)Sc(CH2SiMe3)(2)THF) (4)) were facilely synthesized by alkane elimination reaction of Sc(CH2SiMe3)3(THF)2 with the heterocyclic-fused cyclopentadienyl ligands HL1-4 in high yields. Complexes 1-4 were characterized by H-1 and C-13 NMR spectroscopies and X-ray diffraction analyses as THF-solvated monomers, adopting a half-sandwich geometry. Upon activation of [Ph3C][B(C6F5)(4)]/AliBu(3), these half-sandwich scandium complexes displayed various activities toward the copolymerization of ethylene (E) and dicyclopentadiene (DCPD). Complex 1, supported by the phenyl-substituted pyrrole-fused cyclopentadienyl ligand, showed a slightly higher activity than the phenyl-substituted thiophene-fused cyclopentadienyl complex 2. Among the thiophene-fused cyclopentadienyl complexes 2-4, 4, bearing pentamethyl substituents, showed the highest activity of 2.9 x 10 (6) g/molSc.h.bar. The resultant copolymers had adjustable DCPD incorporation varying from 14.0 up to 46.1 mol %, of which the alternating poly(E-alt-DCPD) had a high Tg of 166 degrees C. In addition, no cross-linking was observed in the copolymers, suggesting that these catalytic systems were highly regioselective for the two active double bonds within DCPD
Ultrathin graphitic C3N4 nanofibers: Hydrolysis-driven top-down rapid synthesis and application as a novel fluorosensor for rapid, sensitive, and selective detection of Fe3+
No full textUltrathin graphitic C3N4(g-C3N4) nanofibers about 5-10 nm in diameters have been rapidly prepared via alkali-catalyzed hydrolysis of bulk g-C3N4 in concentrated alkaline aqueous solution. The morphologies of the g-C3N4 nanostructures can be facilely controlled by varying reaction time, and a scissoring mechanism is proposed to explain the formation process involved. The g-C3N4 nanofibers can serve as a novel fluorosensor for rapid Fe3+ detection with high sensitivity and selectivity. (C) 2015 Elsevier B.V. All rights reserved
Soluble ladder conjugated polypyrrones: Synthesis, characterization and application in photodetectors
No full textLadder conjugated polypyrrones are readily synthesized by condensation of air-stable tetraamines and naphthalene-1,4,5,8-tetracarboxylic acid dianhydride. These rigid-rod ladder polymers are soluble in many common organic solvents and can be cast into thin films for device applications. These polymers are electron-deficient, have a high electron affinity (similar to 4.0 eV) and electron mobility (2.0 x 10(-3) cm(2) V-1 S-1) and show a broad absorption in the visible and near-infrared spectral region. The bulk-heterojunction photovoltaic photodetectors using the electron-deficient polypyrrone as an acceptor together with poly(3-hexyl thiophene) as a donor exhibited the spectral response from 300 to (C) 2014 Elsevier Ltd. All rights reserved.900 nm and specific detectivity in an order of 10(10) Jones at 800 nm. (C) 2014 Elsevier Ltd. All rights reserved
Theoretical insights on the influence of doped Ni in the early stage of graphene growth duringthe CH4 dissociation on Ni-Cu(111) surface
No full textCH4 dissociation on the Ni doped Cu(111) surface has been studied theoretically. Our results show that the doped Ni not only maintains its own activity, but also improves the activity of neighbouring surface Cu atoms during CH4 dissociation. The microkinetic analysis demonstrate that the coverage of CH3 becomes higher than that of CH on surface Ni when H-2/CH4 ratio is larger than 1, while the coverage of CH3 on Cu atom is nearly the same when H-2 is introduced. With the increase of temperature, the branching rate of Ni increases, while that of Cu decreases. Compared with temperature, opposite behavior is found with the increase of H-2/CH4 ratios. Furthermore, the behavior of C atom on Ni Cu(111) is discussed. The doped Ni has little influence for C migration, while it depresses the polymerization process on the neighbouring Cu atoms. Free C atoms produced by CH4 dissociation prefer to dissolve on the site having subsurface Ni atom. Once within the bulk, the C atom will move toward the site where surface Ni exists. Then it will dissolve out to contribute the formation of graphene. (C) 2015 Elsevier B.V. All rights reserved
pH responding reversible supramolecular self-assembly of water-soluble amino-imidazole-armed perylene diimide dye for biological applications
No full textIt is extremely important to design stimuli-responsive biomimetic supramolecular materials. Such type of materials require molecular monomers with multiple functionalities. Perylene diimide (PDI) has been considered as one of the most versatile building block units for supramolecular architecture. However, most of the reported PDI derivatives work in organic media, whereas their application in aqueous systems is a challenge due to the pronounced hydrophobicity of their perylene backbones. Here, we report a water-soluble amino-imidazole-armed perylene diimide (AIA-PDI) dye that discloses reversible supramolecular structure and fluorescence emission conversion upon external pH-stimulation. Such characteristics offer a gap of PDI derivatives in the fabrication of a pH-responsive biomimetic system. Successful application for glucose detection, as a proof of concept, further demonstrates this PDI derivative's biological suitability in pH-responsive systems
Toughening mechanism behind intriguing stress-strain curves in tensile tests of highly enhanced compatibilization of biodegradable poly(lactic acid)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) blends (vol 4, pg 41722, 2014)
No full textMultifunctional polyelectrolyte multilayers coated onto Gd2O3:Yb3+,Er3+@MSNs can be used as drug carriers and imaging agents
No full textMesoporous silica nanoparticles (MSNs) were firstly functionalized with upconversion luminescent Gd2O3:Yb3+, Er3+ via the Pechini sol-gel method. Then, polyelectrolyte multilayers (PEM) composed of poly(allyamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) were coated onto the Gd2O3:Yb3+, Er3+@MSNs using a layer-by-layer (LbL) technique to achieve the pH-responsive properties of the nanocarriers. PEM@Gd2O3:Yb3+, Er3+@MSNs loaded with doxorubicin hydrochloride (DOX) showed pH-responsive release and higher cytotoxicity towards MCF-7 breast cancer cells in vitro. Nanocomposites functionalized with Gd2O3:Yb3+, Er3+ can serve as T-1-weighted magnetic resonance imaging (MRI) contrast agents. Nanoparticles emitting red signals under 980 nm laser excitation are suitable for use in potential bioimaging applications. The upconversion luminescent (UCL) intensity of PEM-coated nanocomposites can be adjusted by controlling the number of layers of the PAH/PSS coating. The PEM@Gd2O3:Yb3+, Er3+@MSNs can be used as a potential drug delivery system for MRI, UCL imaging, and pH-responsive chemotherapy
Small molecular nanomedicines made from a camptothecin dimer containing a disulfide bond
No full textA small molecular camptothecin (CPT) dimer could self-assemble into stable nanoparticles in aqueous solution, which was characterized by TEM and DLS. These nanomedicines could be internalized by cancer cells as revealed by confocal laser scanning microscopy, and indicated high cellular proliferation inhibition toward HeLa and HepG2 cells with low IC50 values and reduction-responsive cytotoxicity towards HeLa cells. The feasible assembly method and outstanding properties of CPT-NPs provide an alternative approach for exploring new nanomedicines for cancer therapy