| 1. |
- Huang, Z. L., et al.
(författare)
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Novel heterocycle-based organic molecules with two-photon induced blue fluorescent emission
- 2003
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 13:4, s. 708-711
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Tidskriftsartikel (refereegranskat)abstract
- Two-photon absorption and two-photon induced blue emission characteristics of a series of heterocycle-based organic molecules are investigated experimentally and by quantum-chemical computations. The molecules consist of a typical A-pi-A' structure, where heterocycle, styryl and formyl groups are employed as A, pi-conjugated and A' moieties, respectively. Experimental results indicate that significant enhancements in the blue emission efficiency and two-photon absorption cross-sections can be achieved by replacing S and O atoms with an N atom in the heterocycle acceptor moiety, which is also supported by the quantum-chemical computations. Additionally, larger two-photon absorption cross-sections can be obtained by choosing appropriate solvents, as indicated by the computations.
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| 2. |
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| 3. |
- Ding, HT, et al.
(författare)
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Parallel cloning, expression, purification and crystallization of human proteins for structural genomics
- 2002
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Ingår i: Acta Crystallographica. Section D: Biological Crystallography. - 1399-0047. ; 58, s. 2102-2108
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Tidskriftsartikel (refereegranskat)abstract
- 54 human genes were selected as test targets for parallel cloning, expression, purification and crystallization. Proteins from these genes were selected to have a molecular weight of between 14 and 50 kDa, not to have a high percentage of hydrophobic residues (i.e. more likely to be soluble) and to have no known crystal structures and were not known to be subunits of heterocomplexes. Four proteins containing transmembrane regions were selected for comparative tests. To date, 44 expression clones have been constructed with the Gateway(TM) cloning system (Invitrogen, The Netherlands). Of these, 35 clones were expressed as recombinant proteins in Escherichia coli strain BL21 (DE3)-pLysS, of which 12 were soluble and four have been purified to homogeneity. Crystallization conditions were screened for the purified proteins in 96-well plates under oil. After further refinement with the same device or by the hanging-drop method, crystals were grown, with needle, plate and prism shapes. A 2.12 Angstrom data set was collected for protein NCC27. The results provide insights into the high-throughput target selection, cloning, expression and crystallization of human genomic proteins.
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| 4. |
- Guo, J. H., et al.
(författare)
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X-ray emission spectroscopy of hydrogen bonding and electronic structure of liquid water
- 2002
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 89:13
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Tidskriftsartikel (refereegranskat)abstract
- We use x-ray emission spectroscopy to examine the influence of the intermolecular interaction on the local electronic structure of liquid water. By comparing x-ray emission spectra of the water molecule and liquid water, we find a strong involvement of the a(1)-symmetry valence-orbital in the hydrogen bonding. The local electronic structure of water molecules, where one hydrogen bond is broken at the hydrogen site, is separately determined. Our results provide an illustration of the important potential of x-ray emission spectroscopy for elucidating basic features of liquids.
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| 5. |
- Kashtanov, Stepan, et al.
(författare)
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Local structures of liquid water studied by x-ray emission spectroscopy
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 69:2
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Tidskriftsartikel (refereegranskat)abstract
- The O Kalpha x-ray emission spectra of water clusters with different sizes and conformations embedded in a continuum medium are simulated. The calculations have successfully explained the experimental spectra of water in both gas and liquid phases. It is shown that the x-ray emission spectra are very sensitive to the local hydrogen bonding structures. Strong electron sharing between different water molecules is observed and its possible connection to the covalency of hydrogen bonding is discussed. The experimentally observed strong excitation energy dependence of the spectra has been interpreted in terms of the polarization and angular dependence for the gas phase, and in terms of variations of local hydrogen bonding structures for the liquid phase.
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| 6. |
- O'Shea, JN, et al.
(författare)
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Hydrogen-bond induced surface core-level shift in isonicotinic acid
- 2001
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Intermolecular hydrogen-bonding in thick films of isonicotinic acid evaporated onto rutile TiO2(110) has been investigated with X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The rate of deposition is found to be a key fac
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| 7. |
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| 8. |
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| 9. |
- Sun, Y. H., et al.
(författare)
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Theoretical studies on nonlinear optical properties of two newly synthesized compounds : PVPHC and DPVPA
- 2004
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 394:03-jan, s. 176-181
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Tidskriftsartikel (refereegranskat)abstract
- The nonlinear optical properties of two newly synthesized molecules 9-(4-{2-[4-(2-pyridin-4-yl-vinyl)-phenyl]-vinyl}-phenyl)-9H-carbazole (PVPHC) and diphenyl-(4-{2-[4-(2-pyridin-4-yl-vinyl)-phenyl]-vinyl}-phenyl)-amine (DPVPA) have been studied using hybrid density functional theory at B3LYP level. A few-state model, as well as response theory, have been employed to calculate their two-photon absorption cross-sections. The theoretical results are in good agreement with the experimental measurements available. It is found that the maximal two-photon absorption cross-sections of these compounds can be well described by a three-state model and both compounds have large two-photon absorption cross-section in optical regime. Strong charge-transfer process upon excitation has been revealed, indicating that these two compounds are good candidates as two-photon polymerization initiators.
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| 10. |
- Sun, Y. H., et al.
(författare)
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Two-photon absorption properties of multi-branched bis-(styryl)benzene based organic chromophores
- 2004
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Ingår i: Journal of Molecular Structure. - : Elsevier BV. - 0166-1280. ; 682:03-jan, s. 185-189
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Tidskriftsartikel (refereegranskat)abstract
- Two-photon absorption (TPA) cross-sections of a series of multi-branched trans-stilbene charge transfer compounds with benzene as the coupling center have been theoretically investigated using analytical response theory at the random phase approximation level. It shows that the TPA cross-sections of compounds with a quasi-one-dimensional geometrical arrangement can be enhanced through the pure electronic coupling of different branches. The effects of different combination of donor/acceptor substitutions on the TPA cross-sections have also been discussed.
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