Silver(I) complexes with halo-substituted cyanoanilines: synthesis, characterization and antibacterial activity

Abstract

Four Ag(I) complexes, [Ag(L1)2](NO3) (1), [Ag(L2)(NO3)] (2), [Ag(L3)3](NO3) (3), and [Ag(L4)2](NO3) (4), with ligands derived from halo-containing cyanoanilines (L1 = 4-amino-3fluorobenzonitrile, L2 = 4-amino-3-chlorobenzonitrile, L3 = 4-amino-3-bromobenzonitrile, L4 = 4-amino-2-bromobenzonitrile) were synthesized and characterized by C, H, and N elemental analysis, IR and 1H NMR spectroscopy and single crystal X-ray diffraction. Complexes 1–4 crystallized in the triclinic space group C2/c, P2(1)/n, P-1 and C2/c, respectively. In 1 and 4, Ag+ is four-coordinate with L1 or L4 to form 1-D ∞{[Ag(L1/L4)2]+} polymeric cations. In 2, Ag+ is three-coordinate by two L2 ligands and one NO3− ligand to form a 1-D ∞{[Ag(L2)(NO3)]} zigzag chain. In 3, Ag+ is four-coordinate by L3 to form a dinuclear [Ag(L3)3]+ cation. The NO3− is a 4-connector bridging group in 1 and 3 and a 5-connector bridging group in 2 and 4. The intermolecular hydrogen bonds and Ag⋯O weak interactions play important roles in forming 3-D networks of 1–4. The antibacterial activities for 1–4 were evaluated against Bacillus subtilis, Staphylococcus aureus and Escherichia coli with MTT method. The antibacterial results indicated that 2 showed the best inhibitory activity against the test bacterial strains, and was as potent as chloramphenicol.