摘要
The complexation of BDHTD （4-benzylidenamino-4,5-dihydro-lH-l,2,4-triazol-5-one derivatives） by divalent doubly charged metal ions M2＋ （M = Mg, Ca, Fe and Cu） has been investigated using the density functional method B3LYP. Two distinct coordination modes （k2-O,O and k2-O,N） have been taken into account. Geometry optimizations have been performed in gas-phase and solution-phase： acetonitrile and DMF （N,N-dimethylformamide） with the basis set 6-31G（d,p）. The B3LYP method was also used to calculate the stability and free energies of the 24 complexes of BDHTD with metal ions M2＋ （M = Mg, Ca, Fe and Cu） respectively in gas-phase and solution-phase： acetonitrile and DMF. Results indicate that k2-O,N structures are most stable in gas-phase. The influence of substitution on the stability is sensitive in solution-phase. The interaction energies of complexation process in various media have been calculated at B3LYP/6-31G（d,p） and CCSD（T） level. The MIA （metal ion affinity） of BDHTD with M2＋ （M = Mg, Ca, Fe and Cu） in various media has been explored. The results show that the M1A highly varies with the coordination mode and substitution effect. From the calculated Gibb energies of complexation in various media, it is revealed that the complexation is possible in gas in acetonitrile. The ligand＇s affinity toward individual cation M2＋ （M = Mg, Ca, Fe and Cu） has been analysed. A significant reduce of BDEs observed confirms the decrease of the antioxidant activity by the metal chelation. The charge transfer induced by metal chelation is examined using the NBO analysis.
