Novel Zn(II) and Cu(II) complexes of the tetraaza-cyclododecane derivatives: Synthesis, characterization and catalytic activity

Shuo Li, Jiaqing Xie, Bingying

Abstract

A series of Zn(II) and Cu(II) complexes of the tetraaza-cyclododecane derivatives were synthesized and characterized with the synthetic routes designed in this work. Azole groups have been designed to work as auxiliary hydrolytically active units in the complexes. The comparison of the catalytic activity in the p-nitrophenyl picolinate (PNPP) hydrolysis was made between the Zn(II) and Cu(II) complexes bearing the tetraaza-cyclododecane derivatives with benzimidazole unit and imidazole unit. The complexes carrying cyclen-benzimidazole showed significant rate acceleration by about 13.6-223 fold larger than the hydrolytic rate catalyzed by Zn(II) cation, and about 43.8-718 times faster than the hydrolysis rate of PNPP without any catalyst. The catalytic activity of the complexes carrying cyclen-benzimidazole was also much stronger than that of cyclen-imidazole. The catalytic function of each group among the catalyst was discussed, and the synergetic effect between cation center and azole group was also proposed in this paper.