Syntheses and antimicrobial activities of two coordination polymers assembled with Ag[sbnd]N and Ag[sbnd]O bonds

Abstract

Two new coordination polymers ({[Ag(p-phda)2](BF4)} n (1) and {[Ag2(1,5-nds)(DMSO)2] DMSO}n (2) (p-phda: p-phenyldiacetonitrile, 1,5-nds: 1,5-naphthalene disulfonic acid, DMSO: dimethyl sulfoxide) were synthesized and characterized by IR, EA,TG and X-ray single crystal diffraction. 1 was revealed as a 2D “fishing net” assembled by AgN bonds with BF4− as equilibrium charge. IR and PXRD analysis showed the BF4− can be irreversibly exchanged by six anions varied in atomic numbers, sizes, configurations and coordination abilities. 2 is constructed by AgO bonds where DMSO function both as guest and bridging ligand. Further diffusion of NO into the solution of 1 and 2 generated two new compounds (1′ and 2′). All four compounds showed excellent broad-spectrum antimicrobial activities against gram-negative bacteria, gram-positive bacteria and yeast. The stronger antibacterial abilities of 1 against S. aureus and P. aeruginosa than those of 2 were evidenced by the smaller minimum inhibitory concentrations of silver ions (AgMICs) and the higher silver ion release rate in aqueous solution. It was concluded that the looser packing of 1 facilitate the silver ions releasing and play a more crucial role than binding mode and ligand-exchangeability. The enhanced P. aeruginosa inhibitions of 1′ and 2′ were elementarily ascribed to NO incorporation, supporting by their increased diameter of inhibition zones and decreased AgMICs.