Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (02): 352-362.doi: 10.3866/PKU.WHXB20110232


Interaction and Properties of Proline-Ag and -Ag+ Complexes

WANG Chao-Jie, CAI Yue-Piao, HUANG Xu-Hui, WEI Tao   

  1. School of Pharmacy, Wenzhou Medical College, Wenzhou 325035, Zhejiang Province, P. R. China
  • Received:2010-08-01 Revised:2010-11-08 Published:2011-01-25
  • Contact: WANG Chao-Jie
  • Supported by:

    The project was supported by the Natural Science Foundation of Zhejiang Province, China (Y404085) and Foundation of Science and Technology Bureau of Wenzhou City, Zhejiang Province, China (Y20080103).


We calculated the geometrical and electronic structures, rotational and vibrational frequencies, and energetics of different complexes formed by 15 conformers of proline (Pro) with atomic and cationic Ag using the hybrid density functional method X3LYP and the LACV3P**++ basis set together with effective core potentials. The Pro-Ag system gave 17 stable complexes and the Pro-Ag+ system gave 23 stable complexes. The results show that: (1) only 9 conformers of proline are present in the Pro-Ag complexes but all are present in the Pro-Ag+ complexes. The most stable complexes are not formed by the lowest energy conformer of proline with Ag and Ag+. (2) The main interaction between atomic Ag and proline is a van der Waals interaction because of its 4d105s1 electronic configuration. However, Ag+ binds strongly to proline with some σ-coordination bonding character due to the empty outermost 5s5p valence shell. Both particles can be mono- or bi-coordinate in complexes with proline. A non-conventional O―H…Ag hydrogen bond exists. (3) The binding energy between Ag and proline is less than -19 kJ·mol-1 but the binding energy of the Pro-Ag+ complex changed from -117 to -255 kJ·mol-1. The latter system was found to be more stable. (4) Ag carries a small amount of negative charge in two types of complexes according to natural bond orbital (NBO) population analysis and the energy differentce of front orbital values (Δε) of the complexes are lower than that of the Ag and proline fragments. The O―H and N―H bond stretching frequencies were found to be red shifted or blue shifted in some complexes.

Key words: X3LYP, Proline, Silver atom, Silver cation, Complex


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