Insights into Structure and Biological Activity of Copper(II) and Zinc(II) Complexes with Triazolopyrimidine Ligands.

In an attempt to increase the biological activity of the 1,2,4-triazolo[1,5- a ]pyrimidine scaffold through complexation with essential metal ions, the complexes trans -[Cu(mptp) 2 Cl 2 ] ( 1 ), [Zn(mptp)Cl 2 (DMSO)] ( 2 ) (mptp: 5-methyl-7-phenyl-1,2,4-triazolo[1,5- a ]pyrimidine), [Cu 2 (dmtp) 4 Cl 4 ]·2H 2 O ( 3 ) and [Zn(dmtp) 2 Cl 2 ] ( 4 ) (dmtp: 5,7-dimethyl-1,2,4-triazolo[1,5- a ]pyrimidine), were synthesized and characterized as new antiproliferative and antimicrobial species. Both complexes ( 1 ) and ( 2 ) crystallize in the P 2 1 /n monoclinic space group, with the tetrahedral surroundings generating a square-planar stereochemistry in the Cu(II) complex and a tetrahedral stereochemistry in the Zn(II) species. The mononuclear units are interconnected in a supramolecular network through π-π interactions between the pyrimidine moiety and the phenyl ring in ( 1 ) while supramolecular chains resulting from C-H∙∙∙π interactions were observed in ( 2 ). All complexes exhibit an antiproliferative effect against B16 tumor cells and improved antibacterial and antifungal activities compared to the free ligands. Complex ( 3 ) displays the best antimicrobial activity against all four tested strains, both in the planktonic and biofilm-embedded states, which can be correlated to its stronger DNA-binding and nuclease-activity traits.