Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (08): 1830-1836.doi: 10.3866/PKU.WHXB201205162


Two Possible Photoreaction Pathways on the L-Valine Optical Isomerization

MA Chi-Cheng1, PU Min1, WEI Min1, LI Jun-Nan1, LI Zhi-Hong2   

  1. 1. State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, P. R. China;
    2. Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, P. R. China
  • Received:2012-03-27 Revised:2012-05-15 Published:2012-07-10
  • Contact: PU Min
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21173019, 11079041).


The photoreaction mechanism of L-valine optical isomerization was studied by the density functional theory (DFT) and ab initio molecular orbital theory. The geometric parameters of reactant, product, intermediates, and transition states on the reaction paths in S0 and T1 states were optimized at the level of B3LYP and MP2 methods and 6-311++G(d, p) basis sets and the reaction energy barriers were obtained by the same methods. The equilibrium geometries on the S1 state of valine were also optimized by the method of time dependent density functional theory (TD-DFT) with B3LYP/6-311++G(d, p) level. Through the analysis of each stationary point geometric feature on the reaction path, the photoreaction mechanisms of L-valine optical isomerization were proposed in which the whole reaction was accomplished through hydrogen transfer with the help of carbonyl O or amino N atom in excited state. Furthermore the effect of solvent on the reaction mechanism of isomers was discussed by the method of polarizable continuum model (PCM) of self consistent reaction field theory.

Key words: Valine, Optical isomerization, Density functional theory, Ab initio molecular orbital theory, Solvent effect


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