Metallomacrocycle or 1D chain: Synthesis, structures, and antifungal activities of zinc(II) and silver(I) complexes based on two reduced Schiff base ligands

Two reduced Schiff base ligands (L-1 and L-2) were synthesized from two Schiff base compounds containing pyridine-2,6-dicarboxamide skeletons. In the presence of Zn(II) or Ag(I) ions, five complexes, formulated as [(ZnLCl2)-Cl-1] (1), [(AgLNO3)-N-1]center dot 4CH(3)CN (2), {[AgL1]center dot NO3 center dot DMSO}(n) (3), {[(ZnLCl2)-Cl-2]center dot 2DMF center dot H2O}(n) (4), and [Ag-2(L-2)(2)(CH3CN)(2)]center dot 2NO(3)center dot 2CH(3)CN (5), were synthesized and further characterized via elemental analysis, FT-IR spectra and single-crystal X-ray diffraction. Complexes 1 and 2 exist as similar mononuclear [1+1] metallomacrocycles. Complexes 3 and 4 exist as 1D zig-zag chain polymers. Complex 5 exists as a centrosymmetric [2+2] metallamacrocycle. The structural differences of the complexes reveal two different configurations of the ligands in coordination with metal ions. Furthermore, antifungal measurements show that all of the three Ag(I) complexes exhibit good inhibiting effects against M. grisea and S. sclerotiorum.