Monomeric Zn(II) and 3D polymeric Ag(I) complexes with a cationic s-triazine hydrazone-based ligand; synthesis, structure, coordination behavior and biological studies

Abstract

Abstract The novel ( E )-6-(2-(1-(pyridin-4-yl)ethylidene)hydrazineyl)-1,3,5-triazine-2,4-diamine ( L ) was used to synthesize the monomeric [Zn(HL)Cl 3 ] ( 1 ) and the 3D polymeric [Ag 4 (HL) 2 (NO 3 ) 6 ] n ( 2 ) complexes. Their structures were verified through single-crystal X-ray diffraction. In both complexes, L is found protonated leading to the cationic coordinating ligand ( HL + ). 1 exhibits a slightly distorted tetrahedral geometry (τ 4 = 0.93 and τ 4 ′=0.92) while 2 contains four crystallographically non-equivalent Ag(I) ions. Ag1 has a square pyramidal geometry (τ 5 = 0.23), Ag2 exhibits a distorted tetrahedron (τ 4 = 0.55 and τ 4 ′=0.54), Ag3 and Ag4 possess a distorted trigonal planar geometry. Hirshfeld surface analysis reveals that hydrogen-based interactions primarily dictate the molecular packing of complexes 1 and 2 (81.3% and 69.2%, respectively). Theoretical NBO analysis was conducted to quantify the flux of electrons from the donor to the acceptor and evaluate the orbital-orbital interactions of the coordinate bonds in both complexes. Regarding to cytotoxicity, 2 achieved impressive results with IC 50 values of 9.96 ± 0.35 and 15.84 ± 0.46 µ M against HepG-2 and MCF-7 cell lines, respectively, surpassing cis -platin by six and four times, respectively. Additionally, 2 exhibits broad-spectrum antimicrobial activity, achieving the most significant activity against B. subtilis , with a diameter of inhibition zone of 27 mm and MIC value of 3.71 µ M, comparable to that of gentamicin as a positive control.