Institute of Chemistry
Changchun Institute of Applied Chemistry, Chinese Academy Of SciencesNot a member yet
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过渡金属Ir(III)配合物光电性质的理论研究
No full text过渡金属磷光配合物在有机发光二极管(OLED)应用方面受到了广泛的关注。由过渡金属原子诱导的自旋轨道耦合(SOC)作用能够在很大程度上排除T1→S0的自旋禁阻跃迁性质，因此，这类配合物能够充分利用单线态激子和三线态激子而发光，进而使得这类磷光OLED器件的内量子效率在理论上可以达到100%。其中，Ir(III)配合物由于具有较高的热稳定性、较短的激发态寿命和较高的量子效率，并且发射光谱可覆盖整个可见光区域，已经被广泛地应用到OLED器件中。本文选取了一系列环金属化的Ir(III)配合物，并利用密度泛函理论(DFT)对其几何结构、吸收/发射光谱和电致发光性质进行了系统的理论研究。 (1) 对比研究了改变主配体和辅助配体对一系列Ir(III)配合物的电子结构、光物理性质以及磷光量子效率的影响。计算结果表明，改变辅助配体对前线分子轨道的能级和分布有很大影响，进而导致了跃迁性质和发射光谱的变化。而...Phosphorescent transition-metal complexes have attracted great attention in the development of highly efficient organic light-emitting diodes (OLEDs). The strong spin-orbital coupling (SOC) effects induced by the transition-metal atom can partially remove the spin-forbidden nature of the T1→S0 radiative relaxation, therefore these complexes can harvest both singlet and triplet excitons as light, leading to a theoretical level of unity for internal quantum efficiency in phosphorescent OLEDs. In particular, Ir(III) complexes, due to their high thermal stability, relatively short excited-state lifetime, high photoluminescence efficiency and excellent emission wavelength tunability, have been most extensively applied in OLEDs. In this dissertation, the electronic structures, absorption and pho..
聚苯胺对镁合金的腐蚀防护机理研究
No full text聚苯胺对多种金属如铁、钢、铜和铝合金都能提供良好的防腐效果，同时聚苯胺在使用过程中不会释放有毒有害物质，有望成为新一代环境友好型的金属防腐材料。与此同时，镁合金由于密度小、比强度高，在汽车、航天行业有着广阔的应用前景，但其容易腐蚀，在实际应用中受到很大限制。近年来，科研人员开展了聚苯胺防腐涂料在镁合金的腐蚀防护上的应用研究，尽管显示出一定的防腐效果，但聚苯胺复合材料涂层在3.5 wt% NaCl溶液中浸泡2个月后开始失效。目前，为提高聚苯胺涂层的防护效果，大多数研究人员着重探索如何提高涂层的屏蔽性能，其实如何发挥聚苯胺涂层的电化学保护作用更为重要，尤其是要揭示聚苯胺对镁合金的防护机理。为此，本论文围绕聚苯胺对镁合金的腐蚀防护效果及防腐机理开展研究，着重研究聚苯胺涂层/镁合金间的界面层的组成、结构以及生长机制，同时作为对比，也研究了聚苯胺对其它金属如锌、铁的腐蚀防护机制。本论文所取得的主要成...The corrosion protection performance of polyaniline (PANI) on various metals such as iron, steel, copper and aluminum alloy has been proved in the past decades, and PANI is expected to be a new environmentally friendly anticorrosion material. Mg alloys has low density and high specific strength which may find applications in automotive and aerospace industries, but such applications are severely limited by their low corrosion resistance feature. Though PANI has shown certain corrosion protection performance on Mg alloys due to the formation of an interlayer between PANI layer and Mg alloy surface, the long-term protection life is still a big concern. To further improve the protection performance of PANI on Mg alloy, it is necessary to understand the composition and growth of the inter-laye..
Synergistic Effects of Intrinsic Cation Disorder and Electron-Deficient Substitution on Ion and Electron Conductivity in La1-xSrxCo0.5Mn0.5O3-delta (x=0, 0.5, and 0.75)
No full textThe effects of intrinsic cation disorder and electron-deficient substitution for La1-xSrxCo0.5Mn0.5O3-delta (LSCM, x = 0, 0.5, and 0.75) on oxygen vacancy formation, and their influence on the electrochemical properties, were revealed through a combination of computer simulation and experimental study. First-principles calculations were first performed and found that the tendency of the oxygen vacancy formation energy was Mn3+-O*-Mn4+ < Co2+-O*-Co3+ < Co2+-O*-Mn4+, meaning that antisite defects not only facilitate the formation of oxygen vacancy but introduce the mixed-valent transition-metal pairs for high electrical conductivity. Detailed partial density of states (PDOS) analysis for Mn on Co sites (Mn-Co) and Co on Mn sites (Co-Mn) indicate that Co2+ is prone to being Co3+ while Mn4+ is prone to being Mn3+ when they are on antisites, respectively. Also it was found that the holes introduced by Sr tend to enter the Co sublattice for x = 0.5 and then the O sublattice when x = 0.75, which further promotes oxygen vacancy formation, and these results are confirmed by both the calculated PDOS results and charge-density difference. On the basis of microscopic predictions, we intentionally synthesized a series of pure LSCM compounds and carried out comprehensive characterization. The crystal structures and their stability were characterized via powder X-ray Rietveld refinements and in situ high-temperature X-ray diffraction. X-ray photoelectron spectroscopy testified to the mixed oxidation states of Co2+/Co3+ and Mn3+/Mn4+. The thermal expansion coefficients were found to match the Ce0.8Sm0.2O2-delta electrolyte well. The electrical conductivities were about 41.4, 140.5, and 204.2 S cm(-1) at doping levels of x = 0, 0.5, and 0.75, and the corresponding impedances were 0.041, 0.027, and 0.022 Omega cm(2) at 850 degrees C, respectively. All of the measured results testify that Sr-doped LaCo0.5Mn0.5O3 compounds are promising cathode materials for intermediate-temperature solid oxide fuel cells
Three-dimensional Fe- and N-incorporated carbon structures as peroxidase mimics for fluorescence detection of hydrogen peroxide and glucose
No full textIn this study, a simple and one-pot pyrolysis strategy is developed for the mass production of Fe, N-incorporated carbon nanotubes in situ grown on 3D porous carbon foam (denoted as Fe-Phen-CFs), which provides highly active Fe-N and doped-N species, and a large surface area with exposed active sites. The obtained composite exhibits intrinsic peroxidase-like catalytic activities. With the Fe-Phen-CFs as the catalyst, the peroxidase substrate of terephthalic acid (TA) can be oxidized to the fluorescent product of hydroxyterephthalate (HTA) by H2O2, which provides a unique strategy for fluorescence detection of H2O2. With such a process, as low as 68 nM H2O2 could be detected with a linear range from 0.1 to 100 mu M. Meanwhile, by integrating glucose oxidase on the Fe-Phen-CFs composite, sensitive detection of glucose is also achieved with a linear range from 0.5 to 200 mM and a limit of detection of 0.19 mM. Most importantly, such a novel TA/Fe-Phen-CFs system can be successfully applied to glucose determination in real human serum samples. The unique nature and 3D structure of the Fe-Phen-CFs composite makes it promising for the fabrication of low-cost, high-performance biosensors
Quantum dots encapsulated glycopolymer vesicles: Synthesis, lectin recognition and photoluminescent properties
No full textBiomimetic star-shaped glycopolymer poly(epsilon-caprolactone)-b-poly(2-aminoethyl methacrylate-b-poly(gluconamidoethylmethacrylate) (SPCL-PAMA-PGAMA) was synthesized by the combination of ring opening polymerization (ROP) and reversible addition-fragmentation chain transfer (RAFT) polymerization. The glycopolymer self-assembled into vesicles with low critical aggregation concentration (CAC) (0.0075 mg/mL). Then, the carboxylic capped CdTe QDs were encapsulated within the glycopolymer vesicles. The QDs encapsulated glycopolymer vesicles (Gly@QDs vesicles) could specifically bind Concanavalin A (Con A) without changing the photoluminescent properties of the Gly@QDs vesicles. Cell viability studies revealed that the cytotoxicity of the Gly@QDs vesicles was remarkably improved as compared to that of the original QDs. The Gly@QDs vesicles were internalized by Hep G2 cells and then emitted green fluorescence in the cells. Consequently, these Gly@QDs vesicles provided a multifunctional platform for targeted delivery and imaging. (C) 2015 Elsevier B.V. All rights reserved
Versatile G-quadruplex-mediated strategies in label-free biosensors and logic systems
No full textG-quadruplex (G4), as one of the significant functional nucleic acids (FNAs), has attracted researchers' wide attention, and in particular has been employed for the construction of label-free molecular sensors and logic systems based on the peroxidase-like activity of the G4-hemin complex and G4-enhanced luminescence of G4-binding organic dyes. Its cation-dependent conformation and stability provide opportunities for the recognition of metal ion inputs and application of a split G4 strategy. Moreover, coupling the G4 sequence with other FNAs, e.g. metal ion-dependent DNAzymes and aptamers, has prominently broadened the range of possible targets from metal ions and DNA to diverse proteins and cells. Although there are limitations, such as a low ability of anti-interference and multiplex analysis, the excellent advantages (e.g. simplicity and low cost) endow the G4-mediated strategy with tremendous potential to be further exploited for practical bioanalysis and complicated DNA computing
MoS2-C/graphite, an electric energy storage device using Na+-based organic electrolytes
No full textMolybdenum disulfide-carbon composite (MoS2-C) sample has been prepared by a hydrothermal method using Na2MoO4, CH4N2S and glucose as starting materials and then calcined at 800 degrees C in an N-2/H-2 mixed atmosphere. X-ray diffraction and N-2 adsorption-desorption tests have been employed to characterize its crystal and pore structure. SEM, TEM and TG methods have been used to investigate its morphology and the weight ratio of carbon. The MoS2-C can be used as the negative electrode for electric energy storage devices using Na+-based organic electrolytes. The charge storage mechanism at the MoS2-C negative electrode has been investigated. Electric energy storage devices using MoS2-C/graphite have been constructed and their electrochemical performance has been studied
Dual-shape memory effect in radiation crosslinked thermoplastic blends: fabrication, optimization and mechanisms
No full textRecently, as an important class of mechanically active smart materials, thermoplastic dual-shape memory polymers (SMPs) have attracted notable attention and can be fabricated in many different manufacturing techniques. Here in this paper, we present experimental results, demonstrating a cost-effective manufacturing technique to enable thermoplastic SMPs with enhanced properties for a wide variety of applications. Thermoplastic SMPs based on low density polyethylene (LDPE) and polypropylene (PP) with various compositions were prepared by melt compounding, followed by a post-processing of e-beam irradiation at 5, 10, 15, 25, 50 and 100 kGy. SEM, DSC, tensile test, rheological properties measurement, sol/gel analysis and shape memory test were performed sequentially to investigate the relationship between the phase morphologies, the content fluctuations, the e-beam irradiation and the shape memory performances. In addition, we also optimized the fabrication process and studied mechanisms of shape memory performances. It was found that the melting point associated to the LDPE soft phase T-m,T-LDPE is almost independent of the content fluctuations. At the same time the mechanical properties (determined at 25 degrees C) and rheological properties (measured at 180 degrees C) can be varied systematically by controlling the structure and radiation dose. More importantly, the results also revealed that (1) irradiated LDPE-rich blends were more suitable and effective than both irradiated PP-rich and nonirradiated blends to be dual-SMPs with advantageous shape memory properties, and (2) increased radiation dose could give rise to enhanced shape recovery capacity without significantly weakening the shape fixity
G-quadruplex DNA/protoporphyrin IX-based synergistic platform for targeted photodynamic cancer therapy
No full textPhotodynamic therapy (PDT) is an emerging technique to induce cancer cell death. However, the tumor specificity, cellular uptake and biodistribution of many photosensitizers urgently need to be improved. In this regard, we show here that the integrated nanoassemblies based on G-quadruplex DNAs (GQDs)/protoporphyrin IX (PPIX) can serve as a synergistic platform for targeted high-performance PDT. In the nanoassemblies, GQDs function as carriers of sensitiser PPIX and confers the system cancer cell targeting ability. After nucleolin-mediated efficient binding and cellular uptake of GQDs/PPIX assemblies, the strong red fluorescence of GQDs/PPIX complex provides a powerful tool for biological imaging. Moreover, the reactive oxygen species (ROS) generated by GQDs/PPIX under light illumination can effectively kill cancer cells. The present approach is simply composed by DNA and photosensitizers, thereby avoiding any complicated and time-consuming covalent modification or chemical labeling procedure. (C) 2014 Published by Elsevier B.V
Synthesis, Structure, and Photoluminescence Properties of Novel KBaSc2(PO4)(3):Ce3+/Eu2+/Tb3+ Phosphors for White-Light-Emitting Diodes
No full textA series of novel KBaSc2(PO4)(3):Ce3+/Eu2+/Tb(3+)phosphors are prepared using a solid-state reaction. X-ray diffraction analysis and Rietveld structure refinement are used to check the phase purity and crystal structure of the prepared samples. Ce3+- and Eu2+-doped phosphors both have broad excitation and emission bands, owing to the spin- and orbital-allowed electron transition between the 4f and 5d energy levels. By co-doping the KBaSc2(PO4)(3):Eu2+ and KBaSc2(PO4)(3):Ce3+ phosphors with Tb3+ ions, tunable colors from blue to green can be obtained. The critical distance between the Eu2+ and Tb3+ ions is calculated by a concentration quenching method and the energy-transfer mechanism for Eu2+Tb3+ is studied by utilizing the Inokuti-Hirayama model. In addition, the quantum efficiencies of the prepared samples are measured. The results indicate that KBaSc2(PO4)(3):Eu2+,Tb3+ and KBaSc2(PO4)(3):Ce3+,Tb3+ phosphors might have potential applications in UV-excited white-light-emitting diodes