Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (01): 32-38.doi: 10.3866/PKU.WHXB20110127

• THEORETICAL AND COMPUTATIONAL CHEMISTRY • Previous Articles     Next Articles

Stability and Electronic Spectra of Chlorin e6 Lysine Amides

WAN Jing-Bai1, LIU Shu-Zhen1, PAN Shu-Ying1, XU Xuan1,2,3, LI Xu1, YE Bing1   

  1. 1. School of Chemistry & Environment, South China Normal University, Guangzhou, 510006, P. R. China;
    2. Key Laboratory of Electrochemical Technology on Energy Storage and Power Generation in Guangdong Universities, Guangzhou 510006, P. R. China;
    3. Engineering Research Center of Materials and Technology for Electrochemical Energy Storage, Ministry of Education of China, South China Normal University, Guangzhou 510006, P. R. China
  • Received:2010-07-24 Revised:2010-10-26 Published:2010-12-31
  • Contact: XU Xuan E-mail:xuxuan@scnu.edu.cn
  • Supported by:

    The project was supported by the Project of Ministry of Education of Guangdong Province, China (2010B090400184) and Natural Science Foundation of Guangdong Province, China (9151063101000037).

Abstract:

The geometric configurations of chlorin e6 and six designed e6 lysine amides were optimized using density functional theory at the B3LYP/6-31G* level. Based on the obtained minimum energy structure, a single point calculation was carried out at the B3LYP/6-31G** level. The electronic spectra of these compounds were calculated using time dependent density functional theory at the LSDA/6-31G** level. The results indicate that the e6 lysine amides, in which the carboxyl of e6 connects with the ε-NH2 of lysine, are more stable. Among them, the 15-acetamide Yε has the highest stability. The formation of lysine amides improves the water-solubility and leads to a slightly poor coplanarity of the chlorin macrocycle in e6. Therefore, the frontier orbital gaps of the e6 lysine amides are slightly higher than that of e6, causing the long wavelength absorption to a small blue-shift of 16-39 nm. The adsorption wavelength is still in the range of 600-900 nm for photodynamic therapy. Furthermore, the long wavelength absorption is strongly affected by the conformation of the molecule. By comparison with Yε, in which the lysine amide group and the chlorin macrocycle are almost coplanar, the planarity of the chlorin ring of Yε1 and Yε2, in which the lysine amide is almost perpendicular to the chlorin ring, is improved and results in red shifts of 53 nm and 50 nm for their long wavelength absorptions, respectively, the average adsorption wavelength of Yε, Yε1, and Yε2 is 18 nm larger than that of e6.

Key words: Density functional theory, Chlorin e6 lysine amide, Electronic absorption spectrum, Stability

MSC2000: 

  • O641