Biomedical subjects

Jingui Qin

Publications and source records attributed to Jingui Qin.

5 recordsLinked to original sources

PubMed2007

From controllable attached isolation moieties to possibly highly efficient nonlinear optical main-chain polyurethanes containing indole-based chromophores.

For the first time, the indole-based NLO chromophores were embedded into the polymer main chain, and different isolation groups were attached to their donor side with the efforts of adjusting the NLO properties of the resultant main-chain polyurethanes, according to the site isolation principle. Thanks to the main-chain structure and the advantages of the indole-based chromophores, all the polymers show excellent transparency, good processability, thermal stability, and relatively good NLO effects. The tested NLO properties of the polymers demonstrate that there is a suitable isolation group present for the sulfonyl-based chromophore to boost its microscopic beta value to a possibly higher macroscopic NLO property efficiently.

Journal Article↗

PubMed2006

Synthesis and characterization of indole-containing chromophores for second-order nonlinear optics.

Push-pull indole-containing nonlinear optical chromophores with different acceptor and pi-conjugated moieties have been synthesized and characterized. Experimental measurements of the second-order nonlinear optical response demonstrated that the chromophores exhibit similar or superior optical nonlinearity compared with their analogues with an aniline moiety as the donor group, but the indole-based chromophores display blue-shifted absorption, even up to 30 nm.

Journal Article↗

PubMed2005

A highly pi-stacked organic semiconductor for field-effect transistors based on linearly condensed pentathienoacene.

We present the synthesis and characterization of a fused-ring compound, dithieno[2,3-d:2',3'-d']thieno[3,2-b:4,5-b']dithiophene (pentathienoacene, PTA). In contrast to pentacene, PTA has a larger band gap than most semiconductors used in organic field-effect transistors (OFETs) and therefore is expected to be stable in air. The large pi-conjugated and planar molecular structure of PTA would also form higher molecular orders that are conductive for carrier transport. X-ray diffraction and atomic force microscopy experiments on its films show that the molecules stack in layers with their long axis upright from the surface. X-ray photoelectron spectroscopy suggests that there are no chemical bonds at the PTA/Au interface. OFETs based on the PTA have been constructed, and their performances as p-type semiconductors are also presented. A high mobility of 0.045 cm(2)/V s and an on/off ratio of 10(3) for a PTA OFET have been achieved, demonstrating the potential of PTA for application in future organic electronics.

Electric Conductivity↗

PubMed2003

A new approach to suppress nonlinearity-transparency trade-off through coordination chemistry: syntheses and spectroscopic study on second-order nonlinear optical properties of a series of square-pyramidal zinc(II) complexes.

Five new square-pyramidal coordination compounds L x Zn(acac)(2) (1-5) (acac = acetylacetonate; L is a variety of thiosemicarbazones: p-dimethylaminobenzaldehyde thiosemicarbazone (1), p-hydroxy-o-methoxybenzaldehyde thiosemicarbazone (2), p-methoxybenzaldehyde thiosemicarbazone (3), p-hydroxybenzaldehyde thiosemicarbazone (4), o-hydroxybenzaldehyde thiosemicarbazone (5)) have been synthesized and characterized by 1H NMR, IR, and elemental analysis. All of these compounds exhibit pretty wide transparent ranges in the visible region. Their electronic absorption spectra have been studied experimentally, and theoretically by ZINDO/S calculation. The latter has also been utilized to estimate the extent of intramolecular charge transfer. The MOPAC software package has been used to evaluate their first-order molecular hyperpolarizabilities (beta). All beta values of the five coordination compounds are larger than those of the corresponding thiosemicarbazones. And complex 1 shows the largest beta(0) (39.1 x 10(-30) esu) in the series.

Magnetic Resonance Spectroscopy↗

PubMed2003

A novel nonlinear optical crystal for the IR region: noncentrosymmetrically crystalline CsCdBr3 and its properties.

A noncentrosymmetric crystal structure of CsCdBr(3) has been successfully observed with X-ray single-crystal structure analysis. It crystallizes in the hexagonal space group P6(3)mc, with a = 7.7281(14) A, b = 7.7281(14) A, c = 6.742(2) A, alpha = 90 degrees, beta = 90 degrees, gamma = 120 degrees, Z = 2. It was obtained by a new preparation procedure different from that reported in the literature that gave a centrosymmetric structure. The structure contains Cd-Br octahedrons, which are connected in a plane-sharing way to form one-dimensional long chains. Each octahedron is slightly distorted, as the three Cd-Br bond lengths are 2.774 A, while the other three Cd-Br bond lengths are 2.804 A. The distortion directions of all of the octahedrons are almost parallel and give rise to the accumulation of the microcosmic nonlinear optical (NLO) coefficient. The Kurtz powder technique shows that CsCdBr(3) has a powder second harmonic generation of about 2 times as large as that of potassium dihydrogen phosphate (KDP). It shows excellent transparency in the visible and infrared regions. The thermal stability is also good. Therefore it may be utilized as a potential nonlinear optical crystal for the IR region.

Journal Article↗