Chem. J. Chinese Universities

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Investigation on Second-order Nonlinear Optical Property of Amino Acid Bridged Chiral Porphyrin Dimmer

YING Xiao1, ZHANG Xin-Wei1, LIAO Shi-Jun2, LIU Hai-Yang2, CHANG Chi-Kwong3   

    1. Department of Applied Physics, South China University of Technology;
    2. Department of Applied Chemistry, South China University of Technology, Guangzhou 510641, China;
    3. Department of Chemistry, The Hong Kong University of Science and Technology, Hong Kong, China
  • Received:2006-01-18 Revised:1900-01-01 Online:2006-12-10 Published:2006-12-10
  • Contact: LIU Hai-Yang

Abstract: Geometries of amino acid bridged bis-porphyrin 1,2,3,4 and their zinc(Ⅱ) complexes were optimized at semiempirical PM3 quantum chemistry level. Static second-order NLO coefficients of these bis-porphyrins were then calculated by TDHF/PM3 method. The calculation results show that all L-type amino acid bridged bis-porphyrins exhibit right-handed helix structures. Within the electric-dipole approximation, second-order NLO coefficients β of these bis-porphyrins change little with the varying of amino acid side chains. However, the second-order NLO chiral components βxyz of amino acid bridged bis-porphyrins are significantly different. The chiral component βxyz and the helix structure parameter r2ζ/L4 matches βxyzr2ζ/L4, indicating the second-order chiral NLO response of helix chiral bis-porphyrins could be well described by one-electron helical model theory. The analysis of β components indicates that these amino acid bridged bis-porphyrins are multipolar molecules with ‖βJ=3‖/‖βJ=1‖≈11—17. In comparison to free-base helix bis-porphyrin, the insertion of Zn(Ⅱ) ion favors the accretion of the second-order NLO dipolar component and chiral component βxyz of molecules.

Key words: Amino acid, Chiral bis-porphyrin, Second-order NLO, TDHF/PM3

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