The synthesis of 1,10‐dihydroxyperylene bisimides by nucleophilic substitution of brominated perylene bisimide is described. 1,10‐Dihydroxyperylene bisimides formed J aggregates in nonpolar solvents and showed a clearly redshifted absorption band. The solvent polarity also influenced the hydrogen bond with the hydroxyl group, and thus, the photophysical properties of perylene bisimide. The photophysical properties of these dihydroxyperylene perylene bisimides can also be tuned by changing charge transfer from the hydroxyl groups to the perylene core through the introduction of metal ions. 相似文献
A bifunctional peptide containing a domain that targets cell nuclei and a domain with the ability to biomineralize and capture Au clusters is presented. The peptide-Au clusters exhibit red emission (λ(em) = 677 nm) and specifically stain the nuclei of three cell lines. 相似文献
Controllable crystal aggregate structures which show highly uniform crystal tubule, rod and cubic like architectures were achieved and the well-defined microrods exhibit outstanding optical waveguide properties. 相似文献
An amorphous phosphorus/carbon nanocomposite demonstrates a reversible 3-Li storage capacity of 2355 mAh g(-1) with an excellent capacity retention of 90% over 100 cycles and a superior power capability with 62% of its capacity realizable at a very high rate of 8000 mA g(-1), possibly serving as a high capacity and high rate alternative anode for next-generation Li-ion batteries. 相似文献
An anion receptor combined different types of hydrogen bond donors such as OH, NH and CH groups has been synthesized. By rotation of the sub methyl group, this receptor showed evident (1)H NMR response to both fluoride and sulfate, while colorimetric and fluorescent responses were only observed in the presence of fluoride. 相似文献
Water permeation across various nitrogen-doped double-walled carbon nanotubes (N-DWCNT) has been studied with molecular dynamics simulations to better understand the influence of water-nanopore interaction on the water permeation rate. There exists a threshold interaction energy at around -34.1 kJ/mol. Over the threshold energy, the water flow through N-DWCNT decreases monotonically with the strengthening of the water-nanotube interaction. The effect on the water flow across the channel is found to be negligible when the interaction energy is weaker than the threshold. The water-nanotube interaction energy can be controlled by doping nitrogen atoms into the nanotube walls. Although the van der Waals interaction energy is much stronger than the electrostatic interaction energy, it is less sensitive to the proportion of doped nitrogen atoms. On the other hand, the electrostatic interaction energy weakens after the initial strengthening when the percentage of doped nitrogen atoms increases to ~25%. The doped nitrogen atoms make less influence on the overall electrostatic interaction energy when the proportion is over 25%, due to the repulsions among themselves. Thus, the monotonous strengthening of the van der Waals interaction energy seems to dominate the overall trend of the total interaction energy, whereas the change of the long-range electrostatic interaction energy characterizes the shape of the correlation curve, as the percentage of doped nitrogen atoms increases. 相似文献
A new non-ionic water-soluble polyfluorene that contains two benzo-18-crown-6 side chains per repeat unit (PFDC) is synthesized and characterized. Upon addition of Pb2+ ions to a solution of PFDC, the PFDC fluorescence is strongly quenched. The minor interference from other metal ions, especial from Cu2+ and Hg2+ions, clearly shows that the PFDC can be used to detect Pb2+ ions with high selectivity. The fluorescence quenching of PFDC in solution originates from the multivalent coordination of the crown-ether moieties to Pb2+ ions followed by precipitation. In comparison to ionic conjugated polymers, the pH of the medium shows less effect on the binding of non-ionic PFDC to Pb2+ ions.
This paper has introduced a pseudo-potential in bond-fluctuation model to simulate oscillatory shear flow of multiple self-avoiding
chains in three dimensions following our previous work under simple shear flow. The oscillatory flow field was reasonably
reproduced by lattice Monte Carlo simulation using this pseudo-potential neglecting hydrodynamic interaction. By sampling
the configuration distribution functions, the macroscopic viscoelasticity of semi-concentrated polymer solution was determined.
Both Newtonian and non-Newtonian regimes were studied. The complex modulus and dynamic viscosity exhibit a reasonable power
relation with oscillatory frequency, which is consistent with present theories and experiments. Consequently, lattice Monte
Carlo simulation has been extended to model free-draining self-avoiding multi chains subject to oscillatory shear flow and
to investigate associated viscoelasticity on the molecular level.
Received: 1 October 1999 Accepted: 19 October 1999 相似文献