Zinc(II) and copper(II) complexes with N-substituted imines derived from 4-amino-1,2,4-triazole: Synthesis, crystal structure, and biological activity

Reactions of copper(II) and zinc(II) acetates with polynitrogen Schiff bases, namely 4-(pyridin-2-yl)methyl-eneamino-1,2,4-triazole (L-1), 4-(pyridin-3-yl)methyleneamino-1,2,4-triazole (L-2) and 4-(pyridin-4-yl)methyl-eneamino-1,2,4-triazole (L-3), were studied. The reaction of Zn(OAc)(2)center dot 2H(2)O and L1 gave crystals of trinuclear complex [Zn-3(OAc)(6)(L-1)(2)] (1). A similar reaction of Zn(OAc)(2)center dot 2H(2)O and L-2 resulted in 1D coordination polymer [Zn(OAc)(2)(L-2)]n (2). The reactions of Cu(OAc)(2)center dot H2O with L-2 or L-3 gave crystals of 1D coordination polymer {[Cu-2(OAc)(4)(L2)]center dot 2MeCN}n (3) and binuclear complex [Cu-2(OAc)(2)(L-3)(2)]center dot 2MeCN (4), respectively. The structures of the coordination compounds thus obtained were determined by single-crystal X-ray diffraction analysis. Complexes 1-4 demonstrated better antibacterial and antifungal activities in comparison with free L-1, L-2, and L-3 ligands: the strongest antimicrobial activity was observed against E. coli for 2 and 3, and the highest antifungal activity was found for 1 and 2.