Liu Juzheng

Optical and nonlinear optical properties of surface-modified CdS nanoparticles

Abstract Hyper-Rayleigh scattering (HRS) technique was used to measure the first-order hyperpolarizability, β , of CdS nanoparticles with different surface-modifying agents (anion of surfactant bis (2-ethylhexyl) sulfosuccinate, disodium salt (named as AOT-SO 3 − ) and pyridine). The ‘per particle’ (4 nm mean diameter) β -values are estimated to fall in the range of 10 −27 esu, which is among the largest values reported for solution species and the β -value of pyridine-modified CdS is 1.4-times smaller than AOT-SO 3 − -modified CdS. As a possible explanation, this difference in the β -values is attributed to the weakening of the two-photon resonance enhancement effect in the pyridine-modified CdS nanoparticles due to the σ-donation formation of pyridine to the Cd 2+ -rich surface of CdS. These were demonstrated by two-photon fluorescence measurements, one-photon fluorescence quenching experiments and photolysis experiments.

Lanthanide ion induced formation of stripes domain structure in phospholipid Langmuir-Blodgett monolayer film observed by atomic force microscopy

Long-range ordered stripes domain structures were observed in Dipalmitoylphosphatidylcholine (DPPC) Langmuir-Blodgett monolayer film which was spread on the subphase of lanthanide ion (Eu3+) solution and transferred to a freshly cleaved mica substrate by vertical deposition. This novel phenomenon was discussed in terms of the competitive interaction of dipole-dipole and electrostatic interactions of the DPPC molecules combined with lanthanide ions with those DPPC molecules free of lanthanide ions.

A novel structure observed on the phospholipid Langmuir-Blodgett bilayer by atomic force microscopy

A novel structure consisting of roundish objects formed on dimyristoyl-phosphatidylcholine (DMPC) Langmuir-Blodgett bilayer films was observed by atomic force microscopy (AFM). Such a structure may have resulted from the collapse of DMPC liposomes formed at the interface of water/organic phase when they have lost the water support.

Molecular positional order in a dipalmitoylphosphatidic acid Langmuir–Blodgett monolayer by atomic force microscopy

Abstract Langmuir–Blodgett monolayers of dipalmitoylphosphatidic acid were studied by using atomic force microscopy on the large- and nano-scale. A molecularly resolved image was achieved at high surface pressure. The monolayer shows a dramatic long-range orientational and positional ordering of molecular organization of aliphatic tails. The ordered molecular arrangement of aliphatic tails may result from the strong intermolecular hydrogen bonding interactions between adjacent phosphate groups in the polar region.

Direct atomic force microscopic evidence of hydrogen bonding interaction in phosphatidic acid Langmuir-Blodgett bilayer

Molecularly resolved atomic force microscopic images of phosphatidic acid Langmuir-Blodgett bilayers show that phosphate groups in polar region of the films are packing in a distorted hexagonal organization with long-range orientational and positional order. Intermolecular hydrogen bonding interactions, which should be responsible for the ordering and stability of bilayers, are visualized directly between adjacent phosphate groups in the polar region of the bilayer. Some adjacent phosphatidic acid molecules link each other through the formation of intermolecular hydrogen bonds between phosphate groups in polar region to form local supramolecules, which provide the bilayers potential as a functionized film in the investigation on the lateral conductions of protons in the biological bilayers.

Molecular image of phosphatidic acid Langmuir-Blodgett trilayer by atomic force microscopy

Abstracts are not published in this journal

Lanthanide-induced shift and relaxation rate studies of the aqueous complexation of citrate

Abstract The aqueous complexation of lanthanide ions with citrate in pH 7.4 solution has been investigated with use of the lanthanide-induced shift and paramagnetic relaxation rate enhancement methods. The results show that the citrate coordinates via hydroxyl and central carboxylate groups with lanthanide ions and forms 1:2 (Ln/cit) isostructural complexes through the lanthanide series. A new possible coordination geometry deduced from our experimental data is suggested and discussed.

Intramolecular Charge Transfer in Arylpyrazolines

Arylpyrazoline microparticles dispersed in water are synthesized and their absorption spectra are compared with those in solution. It is found that the absorbance of pyrazoline group in solution of 5-aryl arylpyrazoline is far greater than that in solution of arylpyrazolines with no 5-aryl group. This hyperchromic effect is intensified in 5-aryl arylpyrazoline microparticles. It is indicated that intramolecular charge transfer exists between pyrazoline group and 5-aryl group and this kind of interaction is increased in their microparticles.

Multi-photon absorption induced fluorescence of a novel compound

The linear and nonlinear fluorescence spectra of 5-(9-anthryl)-3-(4-nitrophenyl)-1-phenyl-2-pyrazoline (ANPP) have been studied in different polarity solvents. The linear fluorescence spectrum of ANPP has two emission bands originating from the anthryl and pyrazoline moieties of ANPP on excitation at 355 nm. The nonlinear two-photon and three-photon fluorescence from these two moieties are observed simultaneously when ANPP is excited at 1064 nm due to the proximity of the absorption bands of these two moieties to λ/3 and λ/2 of the exciting wavelength. The similar spectrum structure indicates that the nonlinear and linear fluorescence originates from the same relaxation process.

Compound Derived from Anthracene and Pyrazol for a Light-Emitting Diode

A new compound, 5-(9-anthryl)-1,3-diphenyl-1H-pyrazol (ADPP), with an anthryl moiety as an emissive group and a diphenylpyrazoline moiety as a charge transporting group is designed and synthesized. The absorption, photoluminescence, electroluminescence, and electrochemistry are measured. Absorption of ADPP is similar to that of anthracene in the vibonic structure but shows slight redshifts because anthryl moiety twists strongly with respect to pyrazol moiety although delocalization still exists between the two moieties. Light-emitting devices fabricated with ADPP show a bright blue emission at 470 nm. The turn-on voltage is 12 V and the light emission follows the current closely, indicating an efficient charge injection and transport for both electrons and holes.