• Title/Summary/Keyword: Chemical-structural properties

Search Result 965, Processing Time 0.024 seconds

Band Electronic Structure Study of Compound $(ET)_2ICl_2$ in Two Structural Modifications

  • Kang Dae Bok
    • Bulletin of the Korean Chemical Society
    • /
    • v.15 no.6
    • /
    • pp.428-432
    • /
    • 1994

  • The crystals of ${\beta}-and\;{\beta}'-(ET)_2ICl_2$ have a modified structure of organic superconductor ${\beta}(ET)_2I_3$. These salts possess strictly different physical properties : the ${\beta}$ phase is a metal but the ${\beta}'$ phase is a semiconductor. Our band electronic structure calculations show that the ${\beta}$ phase is somewhat anisotropic 2D metal and the ${\beta}'$ phase with the 1D character in electronic structure is magnetic insulating, in good agreement with experimental indications.

  • https://doi.org/10.5012/bkcs.1994.15.6.428 인용 PDF

Solvation of a Small Metal-Binding Peptide in Room-Temperature Ionic Liquids

  • Shim, Youngseon;Kim, Hyung J.;Jung, YounJoon
    • Bulletin of the Korean Chemical Society
    • /
    • v.33 no.11
    • /
    • pp.3601-3606
    • /
    • 2012

  • Structural properties of a small hexapeptide molecule modeled after metal-binding siderochrome immersed in a room-temperature ionic liquid (RTIL) are studied via molecular dynamics simulations. We consider two different RTILs, each of which is made up of the same cationic species, 1-butyl-3-methylimidazolium ($BMI^+$), but different anions, hexafluorophosphate ($PF_6{^-}$) and chloride ($Cl^-$). We investigate how anionic properties such as hydrophobicity/hydrophilicity or hydrogen bonding capability affect the stabilization of the peptide in RTILs. To examine the effect of peptide-RTIL electrostatic interactions on solvation, we also consider a hypothetical solvent $BMI^0Cl^0$, a non-ionic counter-part of $BMI^+Cl^-$. For reference, we investigate solvation structures in common polar solvents, water and dimethylsulfoxide (DMSO). Comparison of $BMI^+Cl^-$ and $BMI^0Cl^0$ shows that electrostatic interactions of the peptide and RTIL play a significant role in the conformational fluctuation of the peptide. For example, strong electrostatic interactions between the two favor an extended conformation of the peptide by reducing its structural fluctuations. The hydrophobicity/hydrophilicity of RTIL anions also exerts a notable influence; specifically, structural fluctuations of the peptide become reduced in more hydrophilic $BMI^+Cl^-$, compared with those in more hydrophobic $BMI^+PF_6{^-}$. This is ascribed to the good hydrogen-bond accepting power of chloride anions, which enables them to bind strongly to hydroxyl groups of the peptide and to stabilize its structure. Transport properties of the peptide are examined briefly. Translations of the peptide significantly slow down in highly viscous RTILs.

  • https://doi.org/10.5012/bkcs.2012.33.11.3601 인용 PDF KSCI

Structural and Field-emissive Properties of Carbon Nanotubes Produced by ICP-CVD: Effects of Substrate-Biasing (ICP-CVD 방법으로 성장된 탄소 나노튜브의 구조적 특성 및 전계방출 특성: 기판전압 인가 효과)

  • Park, C.K.;Kim, J.P.;Yun, S.J.;Park, J.S.
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.56 no.1
    • /
    • pp.132-138
    • /
    • 2007

  • Carbon nanotubes (CNTs) arc grown on Ni catalysts employing an inductively-coupled plasma chemical vapor deposition (ICP-CVD) method. The structural and field-emissive properties of the CNTs grown are characterized in terms of the substrate-bias applied. Characterization using the various techniques, such as field-omission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Auger spectroscopy (AES), and Raman spectroscopy, shows that the structural properties of the CNTs, including their physical dimensions and crystal qualities, as well as the nature of vertical growth, are strongly dependent upon the application of substrate bias during CNT growth. It is for the first time observed that the provailing growth mechanism of CNTs, which is either due to tip-driven growth or based-on-catalyst growth, may be influenced by substrate biasing. It is also seen that negatively substrate-biasing would promote the vertical-alignment of the CNTs grown, compared to positively substrate-biasing. However, the CNTs grown under the positively-biased condition display a higher electron-emission capability than those grown under the negatively-biased condition or without any bias applied.

  • PDF KSCI